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CHEMISTRY (614 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 13)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26)
ACS Catalysis     Full-text available via subscription   (Followers: 42)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 20)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 20)
ACS Macro Letters     Full-text available via subscription   (Followers: 25)
ACS Medicinal Chemistry Letters     Full-text available via subscription   (Followers: 40)
ACS Nano     Full-text available via subscription   (Followers: 265)
ACS Photonics     Full-text available via subscription   (Followers: 13)
ACS Synthetic Biology     Full-text available via subscription   (Followers: 23)
Acta Chemica Iasi     Open Access   (Followers: 2)
Acta Chimica Sinica     Full-text available via subscription   (Followers: 1)
Acta Chimica Slovaca     Open Access   (Followers: 1)
Acta Chimica Slovenica     Open Access  
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 6)
Acta Scientifica Naturalis     Open Access   (Followers: 2)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 8)
Adsorption Science & Technology     Full-text available via subscription   (Followers: 5)
Advanced Functional Materials     Hybrid Journal   (Followers: 54)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 65)
Advances in Chemical Science     Open Access   (Followers: 16)
Advances in Chemistry     Open Access   (Followers: 20)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 21)
Advances in Enzyme Research     Open Access   (Followers: 9)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 7)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 15)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 25)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15)
Advances in Polymer Science     Hybrid Journal   (Followers: 43)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 18)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Science and Technology     Full-text available via subscription   (Followers: 12)
African Journal of Bacteriology Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 3)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 7)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
AMB Express     Open Access   (Followers: 1)
Ambix     Hybrid Journal   (Followers: 3)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 61)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Chemistry     Open Access   (Followers: 29)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Hybrid Journal   (Followers: 15)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 164)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 236)
Annales UMCS, Chemia     Open Access  
Annals of Clinical Chemistry and Laboratory Medicine     Open Access   (Followers: 5)
Annual Reports in Computational Chemistry     Full-text available via subscription   (Followers: 3)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 4)
Annual Reports Section B (Organic Chemistry)     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 13)
Anti-Infective Agents     Hybrid Journal   (Followers: 3)
Antiviral Chemistry and Chemotherapy     Hybrid Journal   (Followers: 1)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 8)
Applied Spectroscopy     Full-text available via subscription   (Followers: 22)
Applied Surface Science     Hybrid Journal   (Followers: 31)
Arabian Journal of Chemistry     Open Access   (Followers: 5)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 2)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
Biochemistry     Full-text available via subscription   (Followers: 337)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 9)
Bioinspired Materials     Open Access   (Followers: 5)
Biointerface Research in Applied Chemistry     Open Access   (Followers: 2)
Biointerphases     Open Access   (Followers: 1)
Biology, Medicine, & Natural Product Chemistry     Open Access   (Followers: 1)
Biomacromolecules     Full-text available via subscription   (Followers: 20)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 7)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 119)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 84)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Japan     Full-text available via subscription   (Followers: 24)
Bulletin of the Korean Chemical Society     Hybrid Journal   (Followers: 1)
C - Journal of Carbon Research     Open Access   (Followers: 3)
Cakra Kimia (Indonesian E-Journal of Applied Chemistry)     Open Access  
Canadian Association of Radiologists Journal     Full-text available via subscription   (Followers: 2)
Canadian Journal of Chemistry     Hybrid Journal   (Followers: 10)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 71)
Catalysis for Sustainable Energy     Open Access   (Followers: 7)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysts     Open Access   (Followers: 9)
Cellulose     Hybrid Journal   (Followers: 7)
Cereal Chemistry     Full-text available via subscription   (Followers: 4)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 18)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 73)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 26)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Full-text available via subscription   (Followers: 22)
Chemical Reviews     Full-text available via subscription   (Followers: 181)
Chemical Science     Open Access   (Followers: 23)
Chemical Technology     Open Access   (Followers: 22)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemical Week     Full-text available via subscription   (Followers: 7)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 56)
Chemie-Ingenieur-Technik (Cit)     Hybrid Journal   (Followers: 24)
ChemInform     Hybrid Journal   (Followers: 8)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry & Industry     Hybrid Journal   (Followers: 6)
Chemistry - A European Journal     Hybrid Journal   (Followers: 151)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 20)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Hybrid Journal   (Followers: 2)
Chemistry Letters     Full-text available via subscription   (Followers: 44)
Chemistry of Materials     Full-text available via subscription   (Followers: 245)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 19)
Chemistry-Didactics-Ecology-Metrology     Open Access   (Followers: 1)
ChemistryOpen     Open Access   (Followers: 1)
Chemkon - Chemie Konkret, Forum Fuer Unterricht Und Didaktik     Hybrid Journal  
Chemoecology     Hybrid Journal   (Followers: 4)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 11)
ChemPlusChem     Hybrid Journal   (Followers: 2)
ChemTexts     Hybrid Journal  
CHIMIA International Journal for Chemistry     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemistry     Hybrid Journal   (Followers: 6)
Chinese Journal of Polymer Science     Hybrid Journal   (Followers: 11)
Chromatographia     Hybrid Journal   (Followers: 24)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Cogent Chemistry     Open Access  
Colloid and Interface Science Communications     Open Access  
Colloid and Polymer Science     Hybrid Journal   (Followers: 11)
Colloids and Interfaces     Open Access  
Colloids and Surfaces B: Biointerfaces     Hybrid Journal   (Followers: 6)
Combinatorial Chemistry & High Throughput Screening     Hybrid Journal   (Followers: 5)
Combustion Science and Technology     Hybrid Journal   (Followers: 22)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal   (Followers: 2)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Comprehensive Chemical Kinetics     Full-text available via subscription   (Followers: 1)
Comptes Rendus Chimie     Full-text available via subscription  
Comptes Rendus Physique     Full-text available via subscription   (Followers: 1)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 6)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Croatica Chemica Acta     Open Access  
Crystal Structure Theory and Applications     Open Access   (Followers: 4)
CrystEngComm     Full-text available via subscription   (Followers: 13)
Current Catalysis     Hybrid Journal   (Followers: 2)
Current Chromatography     Hybrid Journal  
Current Green Chemistry     Hybrid Journal  
Current Metabolomics     Hybrid Journal   (Followers: 5)
Current Microwave Chemistry     Hybrid Journal  
Current Opinion in Colloid & Interface Science     Hybrid Journal   (Followers: 9)
Current Opinion in Molecular Therapeutics     Full-text available via subscription   (Followers: 14)
Current Research in Chemistry     Open Access   (Followers: 8)
Current Science     Open Access   (Followers: 70)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 2)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Dislocations in Solids     Full-text available via subscription  
Doklady Chemistry     Hybrid Journal  

        1 2 3 4 | Last

Journal Cover Biosensors
  [SJR: 0.618]   [H-I: 12]   [2 followers]  Follow
  This is an Open Access Journal Open Access journal
   ISSN (Print) 2079-6374
   Published by MDPI Homepage  [198 journals]
  • Biosensors, Vol. 8, Pages 27: Advances in Enzyme-Based Biosensors for
           Pesticide Detection

    • Authors: Bogdan Bucur, Florentina-Daniela Munteanu, Jean-Louis Marty, Alina Vasilescu
      First page: 27
      Abstract: The intensive use of toxic and remanent pesticides in agriculture has prompted research into novel performant, yet cost-effective and fast analytical tools to control the pesticide residue levels in the environment and food. In this context, biosensors based on enzyme inhibition have been proposed as adequate analytical devices with the added advantage of using the toxicity of pesticides for detection purposes, being more “biologically relevant” than standard chromatographic methods. This review proposes an overview of recent advances in the development of biosensors exploiting the inhibition of cholinesterases, photosynthetic system II, alkaline phosphatase, cytochrome P450A1, peroxidase, tyrosinase, laccase, urease, and aldehyde dehydrogenase. While various strategies have been employed to detect pesticides from different classes (organophosphates, carbamates, dithiocarbamates, triazines, phenylureas, diazines, or phenols), the number of practical applications and the variety of environmental and food samples tested remains limited. Recent advances focus on enhancing the sensitivity and selectivity by using nanomaterials in the sensor assembly and novel mutant enzymes in array-type sensor formats in combination with chemometric methods for data analysis. The progress in the development of solar cells enriched the possibilities for efficient wiring of photosynthetic enzymes on different surfaces, opening new avenues for development of biosensors for photosynthesis-inhibiting herbicides.
      Citation: Biosensors
      PubDate: 2018-03-22
      DOI: 10.3390/bios8020027
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 28: Electrochemical Aptasensors for Food and
           Environmental Safeguarding: A Review

    • Authors: Geetesh Mishra, Vinay Sharma, Rupesh Mishra
      First page: 28
      Abstract: Food and environmental monitoring is one of the most important aspects of dealing with recent threats to human well-being and ecosystems. In this framework, electrochemical aptamer-based sensors are resilient due to their ability to resolve food and environmental contamination. An aptamer-based sensor is a compact analytical device combining an aptamer as the bio-sensing element integrated on the transducer surface. Aptamers display many advantages as biorecognition elements in sensor development when compared to affinity-based (antibodies) sensors. Aptasensors are small, chemically unchanging, and inexpensive. Moreover, they offer extraordinary elasticity and expediency in the design of their assemblies, which has led to innovative sensors that show tremendous sensitivity and selectivity. This review will emphasize recent food and environmental safeguarding using aptasensors; there are good prospects for their performance as a supplement to classical techniques.
      Citation: Biosensors
      PubDate: 2018-03-23
      DOI: 10.3390/bios8020028
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 29: Electrochemical Biosensors: A Solution to
           Pollution Detection with Reference to Environmental Contaminants

    • Authors: Gustavo Hernandez-Vargas, Juan Sosa-Hernández, Sara Saldarriaga-Hernandez, Angel Villalba-Rodríguez, Roberto Parra-Saldivar, Hafiz Iqbal
      First page: 29
      Abstract: The increasing environmental pollution with particular reference to emerging contaminants, toxic heavy elements, and other hazardous agents is a serious concern worldwide. Considering this global issue, there is an urgent need to design and develop strategic measuring techniques with higher efficacy and precision to detect a broader spectrum of numerous contaminants. The development of precise instruments can further help in real-time and in-process monitoring of the generation and release of environmental pollutants from different industrial sectors. Moreover, real-time monitoring can also reduce the excessive consumption of several harsh chemicals and reagents with an added advantage of on-site determination of contaminant composition prior to discharge into the environment. With key scientific advances, electrochemical biosensors have gained considerable attention to solve this problem. Electrochemical biosensors can be an excellent fit as an analytical tool for monitoring programs to implement legislation. Herein, we reviewed the current trends in the use of electrochemical biosensors as novel tools to detect various contaminant types including toxic heavy elements. A particular emphasis was given to screen-printed electrodes, nanowire sensors, and paper-based biosensors and their role in the pollution detection processes. Towards the end, the work is wrapped up with concluding remarks and future perspectives. In summary, electrochemical biosensors and related areas such as bioelectronics, and (bio)-nanotechnology seem to be growing areas that will have a marked influence on the development of new bio-sensing strategies in future studies.
      Citation: Biosensors
      PubDate: 2018-03-24
      DOI: 10.3390/bios8020029
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 30: Coverage of Emotion Recognition for Common
           Wearable Biosensors

    • Authors: Terence Hui, R. Sherratt
      First page: 30
      Abstract: The present research proposes a novel emotion recognition framework for the computer prediction of human emotions using common wearable biosensors. Emotional perception promotes specific patterns of biological responses in the human body, and this can be sensed and used to predict emotions using only biomedical measurements. Based on theoretical and empirical psychophysiological research, the foundation of autonomic specificity facilitates the establishment of a strong background for recognising human emotions using machine learning on physiological patterning. However, a systematic way of choosing the physiological data covering the elicited emotional responses for recognising the target emotions is not obvious. The current study demonstrates through experimental measurements the coverage of emotion recognition using common off-the-shelf wearable biosensors based on the synchronisation between audiovisual stimuli and the corresponding physiological responses. The work forms the basis of validating the hypothesis for emotional state recognition in the literature and presents coverage of the use of common wearable biosensors coupled with a novel preprocessing algorithm to demonstrate the practical prediction of the emotional states of wearers.
      Citation: Biosensors
      PubDate: 2018-03-24
      DOI: 10.3390/bios8020030
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 31: Review of Stratum Corneum Impedance
           Measurement in Non-Invasive Penetration Application

    • Authors: Fei Lu, Chenshuo Wang, Rongjian Zhao, Lidong Du, Zhen Fang, Xiuhua Guo, Zhan Zhao
      First page: 31
      Abstract: Due to advances in telemedicine, mobile medical care, wearable health monitoring, and electronic skin, great efforts have been directed to non-invasive monitoring and treatment of disease. These processes generally involve disease detection from interstitial fluid (ISF) instead of blood, and transdermal drug delivery. However, the quantitative extraction of ISF and the level of drug absorption are greatly affected by the individual’s skin permeability, which is closely related to the properties of the stratum corneum (SC). Therefore, measurement of SC impedance has been proposed as an appropriate way for assessing individual skin differences. In order to figure out the current status and research direction of human SC impedance detection, investigations regarding skin impedance measurement have been reviewed in this paper. Future directions are concluded after a review of impedance models, electrodes, measurement methods and systems, and their applications in treatment. It is believed that a well-matched skin impedance model and measurement method will be established for clinical and point-of care applications in the near future.
      Citation: Biosensors
      PubDate: 2018-03-26
      DOI: 10.3390/bios8020031
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 32: Development of a β-Lactoglobulin Sensor
           Based on SPR for Milk Allergens Detection

    • Authors: Jon Ashley, Roberta D’Aurelio, Monika Piekarska, Jeff Temblay, Mike Pleasants, Linda Trinh, Thomas Rodgers, Ibtisam Tothill
      First page: 32
      Abstract: A sensitive and label-free surface plasmon resonance (SPR) based sensor was developed in this work for the detection of milk allergens. β-lactoglobulin (BLG) protein was used as the biomarker for cow milk detection. This is to be used directly in final rinse samples of cleaning in-place (CIP) systems of food manufacturers. The affinity assay was optimised and characterised before a standard curve was performed in pure buffer conditions, giving a detection limit of 0.164 µg mL−1 as a direct binding assay. The detection limit can be further enhanced through the use of a sandwich assay and amplification with nanomaterials. However, this was not required here, as the detection limit achieved exceeded the required allergen detection levels of 2 µg mL−1 for β-lactoglobulin. The binding affinities of the polyclonal antibody for BLG, expressed by the dissociation constant (KD), were equal to 2.59 × 10−9 M. The developed SPR-based sensor offers several advantages in terms of label-free detection, real-time measurements, potential on-line system and superior sensitivity when compared to ELISA-based techniques. The method is novel for this application and could be applied to wider food allergen risk management decision(s) in food manufacturing.
      Citation: Biosensors
      PubDate: 2018-03-27
      DOI: 10.3390/bios8020032
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 33: Smart Garment Fabrics to Enable Non-Contact
           Opto-Physiological Monitoring

    • Authors: Dmitry Iakovlev, Sijung Hu, Harnani Hassan, Vincent Dwyer, Roya Ashayer-Soltani, Chris Hunt, Jinsong Shen
      First page: 33
      Abstract: Imaging photoplethysmography (iPPG) is an emerging technology used to assess microcirculation and cardiovascular signs by collecting backscattered light from illuminated tissue using optical imaging sensors. The aim of this study was to study how effective smart garment fabrics could be capturing physiological signs in a non-contact mode. The present work demonstrates a feasible approach of, instead of using conventional high-power illumination sources, integrating a grid of surface-mounted light emitting diodes (LEDs) into cotton fabric to spotlight the region of interest (ROI). The green and the red LEDs (525 and 660 nm) placed on a small cotton substrate were used to locally illuminate palm skin in a dual-wavelength iPPG setup, where the backscattered light is transmitted to a remote image sensor through the garment fabric. The results show that the illuminations from both wavelength LEDs can be used to extract heart rate (HR) reaching an accuracy of 90% compared to a contact PPG probe. Stretching the fabric over the skin surface alters the morphology of iPPG signals, demonstrating a significantly higher pulsatile amplitude in both channels of green and red illuminations. The skin compression by the fabric could be potentially utilised to enhance the penetration of illumination into cutaneous microvascular beds. The outcome could lead a new avenue of non-contact opto-physiological monitoring and assessment with functional garment fabrics.
      Citation: Biosensors
      PubDate: 2018-03-29
      DOI: 10.3390/bios8020033
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 34: Label-Free Electrochemical Immunoassay for
           C-Reactive Protein

    • Authors: Madasamy Thangamuthu, Christian Santschi, Olivier J. F. Martin
      First page: 34
      Abstract: C-reactive protein (CRP) is one of the most expressed proteins in blood during acute phase inflammation, and its minute level increase has also been recognized for the clinical diagnosis of cardio vascular diseases. Unfortunately, the available commercial immunoassays are labour intensive, require large sample volumes, and have practical limitations, such as low stability and high production costs. Hence, we have developed a simple, cost effective, and label-free electrochemical immunoassay for the measurement of CRP in a drop of serum sample using an immunosensor strip made up of a screen printed carbon electrode (SPE) modified with anti-CRP functionalized gold nanoparticles (AuNPs). The measurement relies on the decrease of the oxidation current of the redox indicator Fe3+/Fe2+, resulting from the immunoreaction between CRP and anti-CRP. Under optimal conditions, the present immunoassay measures CRP in a linear range from 0.4–200 nM (0.047–23.6 µg mL−1), with a detection limit of 0.15 nM (17 ng mL−1, S/N = 3) and sensitivity of 90.7 nA nM−1, in addition to a good reproducibility and storage stability. The analytical applicability of the presented immunoassay is verified by CRP measurements in human blood serum samples. This work provides the basis for a low-priced, safe, and easy-to-use point-of-care immunosensor assay to measure CRP at clinically relevant concentrations.
      Citation: Biosensors
      PubDate: 2018-03-30
      DOI: 10.3390/bios8020034
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 35: Sensors Based on Bio and Biomimetic
           Receptors in Medical Diagnostic, Environment, and Food Analysis

    • Authors: Alisa Kozitsina, Tatiana Svalova, Natalia Malysheva, Andrei Okhokhonin, Marina Vidrevich, Khiena Brainina
      First page: 35
      Abstract: Analytical chemistry is now developing mainly in two areas: automation and the creation of complexes that allow, on the one hand, for simultaneously analyzing a large number of samples without the participation of an operator, and on the other, the development of portable miniature devices for personalized medicine and the monitoring of a human habitat. The sensor devices, the great majority of which are biosensors and chemical sensors, perform the role of the latter. That last line is considered in the proposed review. Attention is paid to transducers, receptors, techniques of immobilization of the receptor layer on the transducer surface, processes of signal generation and detection, and methods for increasing sensitivity and accuracy. The features of sensors based on synthetic receptors and additional components (aptamers, molecular imprinted polymers, biomimetics) are discussed. Examples of bio- and chemical sensors’ application are given. Miniaturization paths, new power supply means, and wearable and printed sensors are described. Progress in this area opens a revolutionary era in the development of methods of on-site and in-situ monitoring, that is, paving the way from the “test-tube to the smartphone”.
      Citation: Biosensors
      PubDate: 2018-04-01
      DOI: 10.3390/bios8020035
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 36: The Use of a Polyphenoloxidase Biosensor
           Obtained from the Fruit of Jurubeba (Solanum paniculatum L.) in the
           Determination of Paracetamol and Other Phenolic Drugs

    • Authors: Rafael Antunes, Luane Garcia, Vernon Somerset, Eric Gil, Flavio Lopes
      First page: 36
      Abstract: The vegetable kingdom is a wide source of a diverse variety of enzymes with broad biotechnological applications. Among the main classes of plant enzymes, the polyphenol oxidases, which convert phenolic compounds to the related quinones, have been successfully used for biosensor development. The oxidation products from such enzymes can be electrochemically reduced, and the sensing is easily achieved by amperometric transducers. In this work, the polyphenoloxidases were extracted from jurubeba (Solanum paniculatum L.) fruits, and the extract was used to construct a carbon paste-based biosensor for pharmaceutical analysis and applications. The assay optimization was performed using a 0.1 mM catechol probe, taking into account the amount of enzymatic extract (50 or 200 μL) and the optimum pH (3.0 to 9.0) as well as some electrochemical differential pulse voltammetric (DPV) parameters (e.g., pulse amplitude, pulse range, pulse width, scan rate). Under optimized conditions, the biosensor was evaluated for the quantitative determination of acetaminophen, acetylsalicylic acid, methyldopa, and ascorbic acid. The best performance was obtained for acetaminophen, which responded linearly in the range between 5 and 245 μM (R = 0.9994), presenting a limit of detection of 3 μM and suitable repeatability ranging between 1.52% and 1.74% relative standard deviation (RSD).
      Citation: Biosensors
      PubDate: 2018-04-02
      DOI: 10.3390/bios8020036
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 37: Functionalized Thick Film Impedance Sensors
           for Use in In Vitro Cell Culture

    • Authors: Heike Bartsch, Martin Baca, Uta Fernekorn, Jens Müller, Andreas Schober, Hartmut Witte
      First page: 37
      Abstract: Multi-electrode arrays find application in electrophysiological recordings. The quality of the captured signals depends on the interfacial contact between electrogenic cells and the electronic system. Therefore, it requires reliable low-impedance electrodes. Low-temperature cofired ceramic technology offers a suitable platform for rapid prototyping of biological reactors and can provide both stable fluid supply and integrated bio-hardware interfaces for recordings in electrogenic cell cultures. The 3D assembly of thick film gold electrodes in in vitro bio-reactors has been demonstrated for neuronal recordings. However, especially when dimensions become small, their performance varies strongly. This work investigates the influence of different coatings on thick film gold electrodes with regard to their influence on impedance behavior. PEDOT:PSS layer, titanium oxynitride and laminin coatings are deposited on LTCC gold electrodes using different 2D and 3D MEA chip designs. Their impedance characteristics are compared and discussed. Titanium oxynitride layers emerged as suitable functionalization. Small 86-µm-electrodes have a serial resistance Rs of 32 kOhm and serial capacitance Cs of 4.1 pF at 1 kHz. Thick film gold electrodes with such coatings are thus qualified for signal recording in 3-dimensional in vitro cell cultures.
      Citation: Biosensors
      PubDate: 2018-04-05
      DOI: 10.3390/bios8020037
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 38: Raman Spectroscopic and Microscopic Analysis
           for Monitoring Renal Osteodystrophy Signatures

    • Authors: John Ciubuc, Marian Manciu, Avudaiappan Maran, Michael Yaszemski, Emma Sundin, Kevin Bennet, Felicia Manciu
      First page: 38
      Abstract: Defining the pathogenesis of renal osteodystrophy (ROD) and its treatment efficacy are difficult, since many factors potentially affect bone quality. In this study, confocal Raman microscopy and parallel statistical analysis were used to identify differences in bone composition between healthy and ROD bone tissues through direct visualization of three main compositional parametric ratios, namely, calcium content, mineral-to-matrix, and carbonate-to-matrix. Besides the substantially lower values found in ROD specimens for these representative ratios, an obvious accumulation of phenylalanine is Raman spectroscopically observed for the first time in ROD samples and reported here. Thus, elevated phenylalanine could also be considered as an indicator of the disease. Since the image results are based on tens of thousands of spectra per sample, not only are the average ratios statistically significantly different for normal and ROD bone, but the method is clearly powerful in distinguishing between the two types of samples. Furthermore, the statistical outcomes demonstrate that only a relatively small number of spectra need to be recorded in order to classify the samples. This work thus opens the possibility of future development of in vivo Raman sensors for assessment of bone structure, remodeling, and mineralization, where different biomarkers are simultaneously detected with unprecedented accuracy.
      Citation: Biosensors
      PubDate: 2018-04-08
      DOI: 10.3390/bios8020038
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 39: Metabolism-Driven High-Throughput Cancer
           Identification with GLUT5-Specific Molecular Probes

    • Authors: Srinivas Kannan, Vagarshak Begoyan, Joseph Fedie, Shuai Xia, Łukasz Weseliński, Marina Tanasova, Smitha Rao
      First page: 39
      Abstract: Point-of-care applications rely on biomedical sensors to enable rapid detection with high sensitivity and selectivity. Despite advances in sensor development, there are challenges in cancer diagnostics. Detection of biomarkers, cell receptors, circulating tumor cells, gene identification, and fluorescent tagging are time-consuming due to the sample preparation and response time involved. Here, we present a novel approach to target the enhanced metabolism in breast cancers for rapid detection using fluorescent imaging. Fluorescent analogs of fructose target the fructose-specific transporter GLUT5 in breast cancers and have limited to no response from normal cells. These analogs demonstrate a marked difference in adenocarcinoma and premalignant cells leading to a novel detection approach. The vastly different uptake kinetics of the analogs yields two unique signatures for each cell type. We used normal breast cells MCF10A, adenocarcinoma cells MCF7, and premalignant cells MCF10AneoT, with hepatocellular carcinoma cells HepG2 as the negative control. Our data indicated that MCF10AneoT and MCF7 cells had an observable difference in response to only one of the analogs. The response, observed as fluorescence intensity, leads to a two-point assessment of the cells in any sample. Since the treatment time is 10 min, there is potential for use in rapid on-site high-throughput diagnostics.
      Citation: Biosensors
      PubDate: 2018-04-10
      DOI: 10.3390/bios8020039
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 40: S-Layer Protein-Based Biosensors

    • Authors: Bernhard Schuster
      First page: 40
      Abstract: The present paper highlights the application of bacterial surface (S-) layer proteins as versatile components for the fabrication of biosensors. One technologically relevant feature of S-layer proteins is their ability to self-assemble on many surfaces and interfaces to form a crystalline two-dimensional (2D) protein lattice. The S-layer lattice on the surface of a biosensor becomes part of the interface architecture linking the bioreceptor to the transducer interface, which may cause signal amplification. The S-layer lattice as ultrathin, highly porous structure with functional groups in a well-defined special distribution and orientation and an overall anti-fouling characteristics can significantly raise the limit in terms of variety and the ease of bioreceptor immobilization, compactness of bioreceptor molecule arrangement, sensitivity, specificity, and detection limit for many types of biosensors. The present paper discusses and summarizes examples for the successful implementation of S-layer lattices on biosensor surfaces in order to give a comprehensive overview on the application potential of these bioinspired S-layer protein-based biosensors.
      Citation: Biosensors
      PubDate: 2018-04-11
      DOI: 10.3390/bios8020040
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 41: Olfactory Dysfunction as a Global Biomarker
           for Sniffing out Alzheimer’s Disease: A Meta-Analysis

    • Authors: Alisha Kotecha, Angelo Corrêa, Kim Fisher, Jo Rushworth
      First page: 41
      Abstract: Cases of Alzheimer’s disease (AD) are rising exponentially due to increasing global life expectancy. There are approximately 50 million sufferers worldwide, with prevalence rising most rapidly in low-income countries such as Africa and Asia. There is currently no definite diagnosis of AD until after death, thus an early biomarker for AD is urgently required in order to administer timelier and more effective interventions. Olfactory dysfunction (problems with the sense of smell) is one of the earliest, preclinical symptoms observed in AD. Olfaction is a promising early biomarker for use worldwide as it is easy, cheap to measure, and not reliant on specialist clinicians or laboratory analysis. We carried out a meta-analysis to determine the credibility of olfaction in diagnosing AD in the preclinical stages, by comparing olfaction in healthy controls against AD patients and patients with mild cognitive impairment (MCI). Data from 10 articles were subjected to two comparative meta-analyses. In the case of AD, the results illustrated that the overall magnitude of effect size was more apparent, d = −1.63, 95% CI [−1.95, −1.31], in comparison to that of MCI, d = −0.81, 95% CI [−1.08, −0.55]. This shows that olfaction worsens progressively as patients progress from MCI to AD, highlighting the potential for olfactory dysfunction to identify AD in the preclinical stages prior to MCI.
      Citation: Biosensors
      PubDate: 2018-04-13
      DOI: 10.3390/bios8020041
      Issue No: Vol. 8, No. 2 (2018)
  • Biosensors, Vol. 8, Pages 4: A Cuprous Oxide Thin Film Non-Enzymatic
           Glucose Sensor Using Differential Pulse Voltammetry and Other Voltammetry
           Methods and a Comparison to Different Thin Film Electrodes on the
           Detection of Glucose in an Alkaline Solution

    • Authors: Yifan Dai, Alireza Molazemhosseini, Kevin Abbasi, Chung Liu
      First page: 4
      Abstract: A cuprous oxide (Cu2O) thin layer served as the base for a non-enzymatic glucose sensor in an alkaline medium, 0.1 NaOH solution, with a linear range of 50–200 mg/dL using differential pulse voltammetry (DPV) measurement. An X-ray photoelectron spectroscopy (XPS) study confirmed the formation of the cuprous oxide layer on the thin gold film sensor prototype. Quantitative detection of glucose in both phosphate-buffered saline (PBS) and undiluted human serum was carried out. Neither ascorbic acid nor uric acid, even at a relatively high concentration level (100 mg/dL in serum), interfered with the glucose detection, demonstrating the excellent selectivity of this non-enzymatic cuprous oxide thin layer-based glucose sensor. Chronoamperometry and single potential amperometric voltammetry were used to verify the measurements obtained by DPV, and the positive results validated that the detection of glucose in a 0.1 M NaOH alkaline medium by DPV measurement was effective. Nickel, platinum, and copper are commonly used metals for non-enzymatic glucose detection. The performance of these metal-based sensors for glucose detection using DPV were also evaluated. The cuprous oxide (Cu2O) thin layer-based sensor showed the best sensitivity for glucose detection among the sensors evaluated.
      Citation: Biosensors
      PubDate: 2018-01-06
      DOI: 10.3390/bios8010004
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 5: Acknowledgement to Reviewers of Biosensors in

    • Authors: Biosensors Editorial Office
      First page: 5
      Abstract: Peer review is an essential part in the publication process, ensuring that Biosensors maintains high quality standards for its published papers.[...]
      Citation: Biosensors
      PubDate: 2018-01-09
      DOI: 10.3390/bios8010005
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 6: Mining the Potential of Label-Free Biosensors
           for In Vitro Antipsychotic Drug Screening

    • Authors: Tugba Kilic, Maria Soler, Nafiseh Fahimi-Kashani, Hatice Altug, Sandro Carrara
      First page: 6
      Abstract: The pharmaceutical industry is facing enormous challenges due to high drug attribution rates. For the past decades, novel methods have been developed for safety and efficacy testing, as well as for improving early development stages. In vitro screening methods for drug-receptor binding are considered to be good alternatives for decreasing costs in the identification of drug candidates. However, these methods require lengthy and troublesome labeling steps. Biosensors hold great promise due to the fact that label-free detection schemes can be designed in an easy and low-cost manner. In this paper, for the first time in the literature, we aimed to compare the potential of label-free optical and impedimetric electrochemical biosensors for the screening of antipsychotic drugs (APDs) based on their binding properties to dopamine receptors. Particularly, we have chosen a currently-used atypical antipsychotic drug (Buspirone) for investigating its dopamine D3 receptor (D3R) binding properties using an impedimetric biosensor and a nanoplasmonic biosensor. Both biosensors have been specifically functionalized and characterized for achieving a highly-sensitive and reliable analysis of drug-D3R binding. Our biosensor strategies allow for comparing different affinities against the D3R, which facilitates the identification of strong or weak dopamine antagonists via in vitro assays. This work demonstrates the unique potential of label-free biosensors for the implementation of cost-efficient and simpler analytical tools for the screening of antipsychotic drugs.
      Citation: Biosensors
      PubDate: 2018-01-09
      DOI: 10.3390/bios8010006
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 7: A Low-Cost Inkjet-Printed Aptamer-Based
           Electrochemical Biosensor for the Selective Detection of Lysozyme

    • Authors: Niazul Khan, Alec Maddaus, Edward Song
      First page: 7
      Abstract: Recently, inkjet-printing has gained increased popularity in applications such as flexible electronics and disposable sensors, as well as in wearable sensors because of its multifarious advantages. This work presents a novel, low-cost immobilization technique using inkjet-printing for the development of an aptamer-based biosensor for the detection of lysozyme, an important biomarker in various disease diagnosis. The strong affinity between the carbon nanotube (CNT) and the single-stranded DNA is exploited to immobilize the aptamers onto the working electrode by printing the ink containing the dispersion of CNT-aptamer complex. The inkjet-printing method enables aptamer density control, as well as high resolution patternability. Our developed sensor shows a detection limit of 90 ng/mL with high target selectivity against other proteins. The sensor also demonstrates a shelf-life for a reasonable period. This technology has potential for applications in developing low-cost point-of-care diagnostic testing kits for home healthcare.
      Citation: Biosensors
      PubDate: 2018-01-15
      DOI: 10.3390/bios8010007
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 8: Antibody Biomimetic Material Made of Pyrrole
           for CA 15-3 and Its Application as Sensing Material in Ion-Selective
           Electrodes for Potentiometric Detection

    • Authors: Alexandra Santos, Felismina Moreira, Luísa Helguero, M. Sales
      First page: 8
      Abstract: This work reports a very simple approach for creating a synthetic antibody against any protein of interest and its application in potentiometric transduction. The selected protein was Breast Cancer Antigen (CA 15-3), which is implicated in breast cancer disease and used to follow-up breast cancer patients during treatment. The new material with antibody-like properties was obtained by molecular-imprinting technology, prepared by electropolymerizing pyrrol (Py, 5.0 × 10−3 mol/L) around Breast Cancer Antigen (CA 15-3) (100 U/mL) on a fluorine doped tin oxide (FTO) conductive glass support. Cyclic voltammetry was employed for this purpose. All solutions were prepared in 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer, of pH 6.5. The biomarker was removed from the imprinted sites by chemical action of ethanol. The biomimetic material was then included in poly vinyl chloride (PVC) plasticized membranes to act as potentiometric ionophore, having or not a lipophilic ionic additive added. The corresponding selective electrodes were evaluated by calibration curves (in buffer and in synthetic serum) and by selectivity testing. The best analytical performance was obtained by selective electrodes including the plastic antibody and no lipophilic additive. The average limits of detection were 1.07 U/mL of CA 15-3, with a linear response from 1.44 to 13.2 U/mL and a cationic slope of 44.5 mV/decade. Overall, the lipophilic additives yielded no advantage to the overall potentiometric performance. The application of the MIP-based electrodes to the analysis of spiked synthetic serum showed precise and accurate results.
      Citation: Biosensors
      PubDate: 2018-01-19
      DOI: 10.3390/bios8010008
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 9: Regenerative, Highly-Sensitive, Non-Enzymatic
           Dopamine Sensor and Impact of Different Buffer Systems in Dopamine Sensing

    • Authors: Saumya Joshi, Vijay Bhatt, Andreas Märtl, Markus Becherer, Paolo Lugli
      First page: 9
      Abstract: Carbon nanotube field-effect transistors are used extensively in ultra-sensitive biomolecule sensing applications. Along with high sensitivity, the possibility of regeneration is highly desired in bio-sensors. An important constituent of such bio-sensing systems is the buffer used to maintain pH and provide an ionic conducting medium, among its other properties. In this work, we demonstrate highly-sensitive regenerative dopamine sensors and the impact of varying buffer composition and type on the electrolyte gated field effect sensors. The role of the buffer system is an often ignored condition in the electrical characterization of sensors. Non-enzymatic dopamine sensors are fabricated and regenerated in hydrochloric acid (HCl) solution. The sensors are finally measured against four different buffer solutions. The impact of the nature and chemical structure of buffer molecules on the dopamine sensors is shown, and the appropriate buffer systems are demonstrated.
      Citation: Biosensors
      PubDate: 2018-01-24
      DOI: 10.3390/bios8010009
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 10: Investigating Colorimetric Protein Array
           Assay Schemes for Detection of Recurrence of Bladder Cancer

    • Authors: Selma Gogalic, Ursula Sauer, Sara Doppler, Claudia Preininger
      First page: 10
      Abstract: A colorimetric microarray for the multiplexed detection of recurrence of bladder cancer including protein markers interleukin-8 (IL8), decorin (DCN), and vascular endothelial growth factor (VEGF) was established to enable easy and cheap read-out by a simple office scanner paving the way for quick therapy monitoring at doctors’ offices. The chip is based on the principle of a sandwich immunoassay and was optimized prior to multiplexing using IL8 as a model marker. Six different colorimetric assay formats were evaluated using a detection antibody (dAB) labeled with (I) gold (Au) nanoparticles (NPs), (II) carbon NPs, (III) oxidized carbon NPs, and a biotinylated dAB in combination with (IV) neutravidin–carbon, (V) streptavidin (strp)–gold, and (VI) strp–horseradish peroxidase (HRP). Assay Format (III) worked best for NP-based detection and showed a low background while the enzymatic approach, using 3,3′,5,5′-tetramethylbenzidine (TMB) substrate, led to the most intense signals with good reproducibility. Both assay formats showed consistent spot morphology as well as detection limits lower than 15 ng/L IL8 and were thus applied for the multiplexed detection of IL8, DCN, and VEGF in synthetic urine. Colorimetric detection in urine (1:3) yields reaction signals and measurement ranges well comparable with detection in the assay buffer, as well as excellent data reproducibility as indicated by the coefficient of variation (CV 5–9%).
      Citation: Biosensors
      PubDate: 2018-01-24
      DOI: 10.3390/bios8010010
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 11: Enzymatic Fuel Cells: Towards Self-Powered
           Implantable and Wearable Diagnostics

    • Authors: Carla Gonzalez-Solino, Mirella Lorenzo
      First page: 11
      Abstract: With the rapid progress in nanotechnology and microengineering, point-of-care and personalised healthcare, based on wearable and implantable diagnostics, is becoming a reality. Enzymatic fuel cells (EFCs) hold great potential as a sustainable means to power such devices by using physiological fluids as the fuel. This review summarises the fundamental operation of EFCs and discusses the most recent advances for their use as implantable and wearable self-powered sensors.
      Citation: Biosensors
      PubDate: 2018-01-29
      DOI: 10.3390/bios8010011
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 12: Glucose Sensing Using Capacitive Biosensor
           Based on Polyvinylidene Fluoride Thin Film

    • Authors: Ambran Hartono, Edi Sanjaya, Ramli Ramli
      First page: 12
      Abstract: A polyvinylidene fluoride (PVDF) film-based capacitive biosensor was developed for glucose sensing. This device consists of a PVDF film sandwiched between two electrodes. A capacitive biosensor measures the dielectric properties of the dielectric layers at the interface between the electrolyte and the electrode. A glucose oxidase (GOx) enzyme was immobilized onto the electrode to oxidize glucose. In practice, the biochemical reaction of glucose with the GOx enzyme generates free electron carriers. Consequently, the potential difference between the electrodes is increased, resulting in a measurable voltage output of the biosensor. The device was tested for various glucose concentrations in the range of 0.013 to 5.85 M, and various GOx enzyme concentrations between 4882.8 and 2.5 million units/L. We found that the sensor output increased with increasing glucose concentration up to 5.85 M. These results indicate that the PVDF film-based capacitive biosensors can be properly applied to glucose sensing and provide opportunities for the low-cost fabrication of glucose-based biosensors based on PVDF materials.
      Citation: Biosensors
      PubDate: 2018-01-30
      DOI: 10.3390/bios8010012
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 13: Prolonged Corrosion Stability of a Microchip
           Sensor Implant during In Vivo Exposure

    • Authors: Paul Glogener, Michael Krause, Jens Katzer, Markus Schubert, Mario Birkholz, Olaf Bellmann, Claudia Kröger-Koch, Harald Hammon, Cornelia Metges, Christine Welsch, Roman Ruff, Klaus Hoffmann
      First page: 13
      Abstract: A microelectronic biosensor was subjected to in vivo exposure by implanting it in the vicinity of m. trapezii (Trapezius muscle) from cattle. The implant is intended for the continuous monitoring of glucose levels, and the study aimed at evaluating the biostability of exposed semiconductor surfaces. The sensor chip was a microelectromechanical system (MEMS) prepared using 0.25 µm complementary metal–oxide–semiconductor CMOS/BiCMOS technology. Sensing is based on the principle of affinity viscometry with a sensoric assay, which is separated by a semipermeable membrane from the tissue. Outer dimensions of the otherwise hermetically sealed biosensor system were 39 × 49 × 16 mm. The test system was implanted into cattle in a subcutaneous position without running it. After 17 months, the device was explanted and analyzed by comparing it with unexposed chips and systems. Investigations focused on the MEMS chip using SEM, TEM, and elemental analysis by EDX mapping. The sensor chip turned out to be uncorroded and no diminishing of the topmost passivation layer could be determined, which contrasts remarkably with previous results on CMOS biosensors. The negligible corrosive attack is understood to be a side effect of the semipermeable membrane separating the assay from the tissue. It is concluded that the separation has enabled a prolonged biostability of the chip, which will be of relevance for biosensor implants in general.
      Citation: Biosensors
      PubDate: 2018-02-01
      DOI: 10.3390/bios8010013
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 14: Self-Organized Nanostructure Modified
           Microelectrode for Sensitive Electrochemical Glutamate Detection in Stem
           Cells-Derived Brain Organoids

    • Authors: Babak Nasr, Rachael Chatterton, Jason Yong, Pegah Jamshidi, Giovanna D’Abaco, Andrew Bjorksten, Omid Kavehei, Gursharan Chana, Mirella Dottori, Efstratios Skafidas
      First page: 14
      Abstract: Neurons release neurotransmitters such as glutamate to communicate with each other and to coordinate brain functioning. As increased glutamate release is indicative of neuronal maturation and activity, a system that can measure glutamate levels over time within the same tissue and/or culture system is highly advantageous for neurodevelopmental investigation. To address such challenges, we develop for the first time a convenient method to realize functionalized borosilicate glass capillaries with nanostructured texture as an electrochemical biosensor to detect glutamate release from cerebral organoids generated from human embryonic stem cells (hESC) that mimic various brain regions. The biosensor shows a clear catalytic activity toward the oxidation of glutamate with a sensitivity of 93 ± 9.5 nA·µM−1·cm−2. It was found that the enzyme-modified microelectrodes can detect glutamate in a wide linear range from 5 µM to 0.5 mM with a limit of detection (LOD) down to 5.6 ± 0.2 µM. Measurements were performed within the organoids at different time points and consistent results were obtained. This data demonstrates the reliability of the biosensor as well as its usefulness in measuring glutamate levels across time within the same culture system.
      Citation: Biosensors
      PubDate: 2018-02-05
      DOI: 10.3390/bios8010014
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 15: Probing Contaminant-Induced Alterations in
           Chlorophyll Fluorescence by AC-Dielectrophoresis-Based 2D-Algal Array

    • Authors: Coralie Siebman, Orlin Velev, Vera Slaveykova
      First page: 15
      Abstract: The investigation of contaminant impact on algae requires rapid and reliable cell collection and optical detection. The capability of alternative current (AC) dielectrophoresis (DEP) collection of whole cell arrays with combined fluorescence microscopy detection to follow the alterations of chlorophyll fluorescence during environmental contaminant exposure was explored. The application of an AC-field of 100 V cm−1, 100 Hz for 30 min to capture and immobilize the cells of green alga Chlamydomonas reinhardtii in two-dimensional (2D) arrays does not induce changes in chlorophyll fluorescence. The results demonstrate that DEP-based 2D-arrays allow non-invasive detection of chlorophyll fluorescence change upon exposure to high concentrations of copper oxide nanoparticles and ionic copper. These results were in agreement with data obtained by flow cytometry used as a comparative method. The tool was also applied to follow the effect of a number of ubiquitous contaminants such as inorganic mercury, methylmercury, and diuron. However, a statistically significant short-term effect was observed only for mercury. Overall, DEP-based 2D-arrays of algal cells with fluorescence detection appear to be suitable for stain-free probing the effects on the photosynthetic microorganisms in highly polluted environment.
      Citation: Biosensors
      PubDate: 2018-02-11
      DOI: 10.3390/bios8010015
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 16: Ultrasensitive Determination of Malathion
           Using Acetylcholinesterase Immobilized on Chitosan-Functionalized Magnetic
           Iron Nanoparticles

    • Authors: Núbia Rodrigues, Sakae Neto, Rita Luz, Flávio Damos, Hideko Yamanaka
      First page: 16
      Abstract: A renewable, disposable, low cost, and sensitive sensor for the detection of organophosphorus pesticides was constructed by immobilizing the acetylcholinesterase enzyme (AChE), via glutaraldehyde, on magnetic iron nanoparticles (Fe3O4) previously synthesized and functionalized with chitosan (CS). The sensor was denoted AChE/CS/Fe3O4. The magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. Acetylthiocholine (ATCh) was incubated with AChE/CS/Fe3O4 and attached to a screen-printed electrode using a magnet. The oxidation of thiocholine (from ATCh hydrolysis) was monitored at an applied potential of +0.5 V vs. Ag/AgCl(KClsat) in 0.1 mol L−1 phosphate buffer solution (pH 7.5) as the supporting electrolyte. A mixture of the pesticide malathion and ATCh was investigated using the same procedure, and the results were compared and expressed as inhibition percentages. For determination of malathion, the proposed sensor presented a linear response in the range from 0.5 to 20 nmol L−1 (R = 0.9942). The limits of detection (LOD) and quantification (LOQ) were 0.3 and 0.8 nmol L−1, respectively. Real samples were also investigated, with recovery values of 96.0% and 108.3% obtained for tomato and pond water samples, respectively. The proposed sensor is a feasible option for malathion detection, offering a linear response, good sensitivity, and a low detection limit.
      Citation: Biosensors
      PubDate: 2018-02-13
      DOI: 10.3390/bios8010016
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 17: Simple Approaches to Minimally-Instrumented,
           Microfluidic-Based Point-of-Care Nucleic Acid Amplification Tests

    • Authors: Michael Mauk, Jinzhao Song, Changchun Liu, Haim Bau
      First page: 17
      Abstract: Designs and applications of microfluidics-based devices for molecular diagnostics (Nucleic Acid Amplification Tests, NAATs) in infectious disease testing are reviewed, with emphasis on minimally instrumented, point-of-care (POC) tests for resource-limited settings. Microfluidic cartridges (‘chips’) that combine solid-phase nucleic acid extraction; isothermal enzymatic nucleic acid amplification; pre-stored, paraffin-encapsulated lyophilized reagents; and real-time or endpoint optical detection are described. These chips can be used with a companion module for separating plasma from blood through a combined sedimentation-filtration effect. Three reporter types: Fluorescence, colorimetric dyes, and bioluminescence; and a new paradigm for end-point detection based on a diffusion-reaction column are compared. Multiplexing (parallel amplification and detection of multiple targets) is demonstrated. Low-cost detection and added functionality (data analysis, control, communication) can be realized using a cellphone platform with the chip. Some related and similar-purposed approaches by others are surveyed.
      Citation: Biosensors
      PubDate: 2018-02-26
      DOI: 10.3390/bios8010017
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 18: A Real-Time Thermal Self-Elimination Method
           for Static Mode Operated Freestanding Piezoresistive Microcantilever-Based

    • Authors: Yu-Fu Ku, Long-Sun Huang, Yi-Kuang Yen
      First page: 18
      Abstract: Here, we provide a method and apparatus for real-time compensation of the thermal effect of single free-standing piezoresistive microcantilever-based biosensors. The sensor chip contained an on-chip fixed piezoresistor that served as a temperature sensor, and a multilayer microcantilever with an embedded piezoresistor served as a biomolecular sensor. This method employed the calibrated relationship between the resistance and the temperature of piezoresistors to eliminate the thermal effect on the sensor, including the temperature coefficient of resistance (TCR) and bimorph effect. From experimental results, the method was verified to reduce the signal of thermal effect from 25.6 μV/°C to 0.3 μV/°C, which was approximately two orders of magnitude less than that before the processing of the thermal elimination method. Furthermore, the proposed approach and system successfully demonstrated its effective real-time thermal self-elimination on biomolecular detection without any thermostat device to control the environmental temperature. This method realizes the miniaturization of an overall measurement system of the sensor, which can be used to develop portable medical devices and microarray analysis platforms.
      Citation: Biosensors
      PubDate: 2018-02-28
      DOI: 10.3390/bios8010018
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 19: A DNA-Based Assay for Digoxin Detection

    • Authors: Michael Kjelstrup, Line Nielsen, Malthe Hansen-Bruhn, Kurt Gothelf
      First page: 19
      Abstract: The most common method for quantifying small-molecule drugs in blood samples is by liquid chromatography in combination with mass spectrometry. Few immuno-based assays are available for the detection of small-molecule drugs in blood. Here we report on a homogeneous assay that enables detection of the concentration of digoxin spiked into in a plasma sample. The assay is based on a shift in the equilibrium of a DNA strand displacement competition reaction, and can be performed in 30 min for concentrations above 10 nM. The equilibrium shift occurs upon binding of anti-digoxigenin antibody. As a model, the assay provides a potential alternative to current small-molecule detection methods used for therapeutic drug monitoring.
      Citation: Biosensors
      PubDate: 2018-03-06
      DOI: 10.3390/bios8010019
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 20: Amperometric Self-Referencing Ceramic Based
           Microelectrode Arrays for D-Serine Detection

    • Authors: Diana Campos-Beltrán, Åsa Konradsson-Geuken, Jorge Quintero, Lisa Marshall
      First page: 20
      Abstract: D-serine is the major D-amino acid in the mammalian central nervous system. As the dominant co-agonist of the endogenous synaptic NMDA receptor, D-serine plays a role in synaptic plasticity, learning, and memory. Alterations in D-serine are linked to neuropsychiatric disorders including schizophrenia. Thus, it is of increasing interest to monitor the concentration of D-serine in vivo as a relevant player in dynamic neuron-glia network activity. Here we present a procedure for amperometric detection of D-serine with self-referencing ceramic-based microelectrode arrays (MEAs) coated with D-amino acid oxidase from the yeast Rhodotorula gracilis (RgDAAO). We demonstrate in vitro D-serine recordings with a mean sensitivity of 8.61 ± 0.83 pA/µM to D-serine, a limit of detection (LOD) of 0.17 ± 0.01 µM, and a selectivity ratio of 80:1 or greater for D-serine over ascorbic acid (mean ± SEM; n = 12) that can be used for freely moving studies.
      Citation: Biosensors
      PubDate: 2018-03-06
      DOI: 10.3390/bios8010020
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 21: A Nanostructured Sensor Based on Gold
           Nanoparticles and Nafion for Determination of Uric Acid

    • Authors: Natalia Stozhko, Maria Bukharinova, Leonid Galperin, Khiena Brainina
      First page: 21
      Abstract: The paper discusses the mechanism of uric acid (UA) electrooxidation occurring on the surface of gold nanoparticles. It has been shown that the electrode process is purely electrochemical, uncomplicated with catalytic stages. The nanoeffects observed as the reduction of overvoltage and increased current of UA oxidation have been described. These nanoeffects are determined by the size of particles and do not depend on the method of particle preparation (citrate and “green” synthesis). The findings of these studies have been used to select a modifier for carbon screen-printed electrode (CSPE). It has been stated that CSPE modified with gold nanoparticles (5 nm) and 2.5% Nafion (Nf) may serve as non-enzymatic sensor for UA determination. The combination of the properties of nanoparticles and Nafion as a molecular sieve at the selected pH 5 phosphate buffer solution has significantly improved the resolution of the sensor compared to unmodified CSPE. A nanostructured sensor has demonstrated good selectivity in determining UA in the presence of ascorbic acid. The detection limit of UA is 0.25 μM. A linear calibration curve has been obtained over a range of 0.5–600 μM. The 2.5%Nf/Au(5nm)/CSPE has been successfully applied to determining UA in blood serum and milk samples. The accuracy and reliability of the obtained results have been confirmed by a good correlation with the enzymatic spectrophotometric analysis (R2 = 0.9938) and the “added−found” technique (recovery close to 100%).
      Citation: Biosensors
      PubDate: 2018-03-06
      DOI: 10.3390/bios8010021
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 22: Accuracy of Continuous Glucose Monitoring
           before, during, and after Aerobic and Anaerobic Exercise in Patients with
           Type 1 Diabetes Mellitus

    • Authors: Lyvia Biagi, Arthur Bertachi, Carmen Quirós, Marga Giménez, Ignacio Conget, Jorge Bondia, Josep Vehí
      First page: 22
      Abstract: Continuous glucose monitoring (CGM) plays an important role in treatment decisions for patients with type 1 diabetes under conventional or closed-loop therapy. Physical activity represents a great challenge for diabetes management as well as for CGM systems. In this work, the accuracy of CGM in the context of exercise is addressed. Six adults performed aerobic and anaerobic exercise sessions and used two Medtronic Paradigm Enlite-2 sensors under closed-loop therapy. CGM readings were compared with plasma glucose during different periods: one hour before exercise, during exercise, and four hours after the end of exercise. In aerobic sessions, the median absolute relative difference (MARD) increased from 9.5% before the beginning of exercise to 16.5% during exercise (p < 0.001), and then decreased to 9.3% in the first hour after the end of exercise (p < 0.001). For the anaerobic sessions, the MARD before exercise was 15.5% and increased without statistical significance to 16.8% during exercise realisation (p = 0.993), and then decreased to 12.7% in the first hour after the cessation of anaerobic activities (p = 0.095). Results indicate that CGM might present lower accuracy during aerobic exercise, but return to regular operation a few hours after exercise cessation. No significant impact for anaerobic exercise was found.
      Citation: Biosensors
      PubDate: 2018-03-09
      DOI: 10.3390/bios8010022
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 23: Biosensors for Sustainable Food Engineering:
           Challenges and Perspectives

    • Authors: Suresh Neethirajan, Vasanth Ragavan, Xuan Weng, Rohit Chand
      First page: 23
      Abstract: Current food production faces tremendous challenges from growing human population, maintaining clean resources and food qualities, and protecting climate and environment. Food sustainability is mostly a cooperative effort resulting in technology development supported by both governments and enterprises. Multiple attempts have been promoted in tackling challenges and enhancing drivers in food production. Biosensors and biosensing technologies with their applications, are being widely applied to tackling top challenges in food production and its sustainability. Consequently, a growing demand in biosensing technologies exists in food sustainability. Microfluidics represents a technological system integrating multiple technologies. Nanomaterials, with its technology in biosensing, is thought to be the most promising tool in dealing with health, energy, and environmental issues closely related to world populations. The demand of point of care (POC) technologies in this area focus on rapid, simple, accurate, portable, and low-cost analytical instruments. This review provides current viewpoints from the literature on biosensing in food production, food processing, safety and security, food packaging and supply chain, food waste processing, food quality assurance, and food engineering. The current understanding of progress, solution, and future challenges, as well as the commercialization of biosensors are summarized.
      Citation: Biosensors
      PubDate: 2018-03-12
      DOI: 10.3390/bios8010023
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 24: Calibration of Minimally Invasive Continuous
           Glucose Monitoring Sensors: State-of-The-Art and Current Perspectives

    • Authors: Giada Acciaroli, Martina Vettoretti, Andrea Facchinetti, Giovanni Sparacino
      First page: 24
      Abstract: Minimally invasive continuous glucose monitoring (CGM) sensors are wearable medical devices that provide real-time measurement of subcutaneous glucose concentration. This can be of great help in the daily management of diabetes. Most of the commercially available CGM devices have a wire-based sensor, usually placed in the subcutaneous tissue, which measures a “raw” current signal via a glucose-oxidase electrochemical reaction. This electrical signal needs to be translated in real-time to glucose concentration through a calibration process. For such a scope, the first commercialized CGM sensors implemented simple linear regression techniques to fit reference glucose concentration measurements periodically collected by fingerprick. On the one hand, these simple linear techniques required several calibrations per day, with the consequent patient’s discomfort. On the other, only a limited accuracy was achieved. This stimulated researchers to propose, over the last decade, more sophisticated algorithms to calibrate CGM sensors, resorting to suitable signal processing, modelling, and machine-learning techniques. This review paper will first contextualize and describe the calibration problem and its implementation in the first generation of CGM sensors, and then present the most recently-proposed calibration algorithms, with a perspective on how these new techniques can influence future CGM products in terms of accuracy improvement and calibration reduction.
      Citation: Biosensors
      PubDate: 2018-03-13
      DOI: 10.3390/bios8010024
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 25: The Use of Biosensors to Explore the
           Potential of Probiotic Strains to Reduce the SOS Response and Mutagenesis
           in Bacteria

    • Authors: Vladimir Chistyakov, Evgeniya Prazdnova, Maria Mazanko, Anzhelica Bren
      First page: 25
      Abstract: A model system based on the Escherichia coli MG1655 (pRecA-lux) Lux-biosensor was used to evaluate the ability of the fermentates of eight probiotic strains to reduce the SOS response stimulated by ciprofloxacin in bacteria and mutagenesis mediated by it. Preliminary attempts to estimate the chemical nature of active components of the fermentates were conducted.
      Citation: Biosensors
      PubDate: 2018-03-16
      DOI: 10.3390/bios8010025
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 26: Fabrication of SrTiO3 Layer on Pt Electrode
           for Label-Free Capacitive Biosensors

    • Authors: Francesca Malvano, Luigi Maritato, Giovanni Carapella, Pasquale Orgiani, Roberto Pilloton, Marisa Di Matteo, Donatella Albanese
      First page: 26
      Abstract: Due to their interesting ferroelectric, conductive and dielectric properties, in recent years, perovskite-structured materials have begun to attract increasing interest in the biosensing field. In this study, a strontium titanate perovskite layer (SrTiO3) has been synthesized on a platinum electrode and exploited for the development of an impedimetric label-free immunosensor for Escherichia coli O157:H7 detection. The electrochemical characterization of the perovskite-modified electrode during the construction of the immunosensor, as well as after the interaction with different E. coli O157:H7 concentrations, showed a reproducible decrease of the total capacitance of the system that was used for the analytical characterization of the immunosensor. Under optimized conditions, the capacitive immunosensor showed a linear relationship from to 1 to 7 log cfu/mL with a low detection limit of 1 log cfu/mL. Moreover, the atomic force microscopy (AFM) technique underlined the increase in roughness of the SrTiO3-modified electrode surface after antibody immobilization, as well as the effective presence of cells with the typical size of E. coli.
      Citation: Biosensors
      PubDate: 2018-03-16
      DOI: 10.3390/bios8010026
      Issue No: Vol. 8, No. 1 (2018)
  • Biosensors, Vol. 8, Pages 1: Label-Free Biosensor Detection of Endocrine
           Disrupting Compounds Using Engineered Estrogen Receptors

    • Authors: Rita La Spina, Valentina Ferrero, Venera Aiello, Mattia Pedotti, Luca Varani, Teresa Lettieri, Luigi Calzolai, Willem Haasnoot, Pascal Colpo
      First page: 1
      Abstract: Endocrine Disrupting Compounds (EDCs) are chemical substances shown to interfere with endogenous hormones affecting the endocrine, immune and nervous systems of mammals. EDCs are the causative agents of diseases including reproductive disorders and cancers. This highlights the urgency to develop fast and sensitive methods to detect EDCs, which are detrimental even at very low concentrations. In this work, we propose a label-free surface plasmon resonance (SPR) biosensor method to detect specific EDCs (17 β-estradiol (E2), ethinyl-estradiol, 4-nonylphenol, tamoxifen) through their binding to estrogen receptor alpha (ERα). We show that the use of rationally designed ERα (as bio-recognition element) in combination with conformation-sensitive peptides (as amplification agent, resulting in increased responses) enables the detection of low parts per billion (ppb) levels of E2. As a proof of concept, this bioassay was used to detect E2 in (spiked) real water samples from fish farms, rivers and the sea at low ppb levels after concentration by solid phase extraction. In addition, the present SPR assay that combines a conformation-sensitive peptide with an array of ERα mutants is very promising for the assessment of the risk of potential estrogenic activity for chemical substances.
      Citation: Biosensors
      PubDate: 2017-12-22
      DOI: 10.3390/bios8010001
      Issue No: Vol. 8, No. 1 (2017)
  • Biosensors, Vol. 8, Pages 2: An FT-Raman, FT-IR, and Quantum Chemical
           Investigation of Stanozolol and Oxandrolone

    • Authors: Tibebe Lemma, Fabiano de Barros Souza, Claudio Tellez Soto, Airton Martin
      First page: 2
      Abstract: We have studied the Fourier Transform Infrared (FT-IR) and the Fourier transform Raman (FT-Raman) spectra of stanozolol and oxandrolone, and we have performed quantum chemical calculations based on the density functional theory (DFT) with a B3LYP/6-31G (d, p) level of theory. The FT-IR and FT-Raman spectra were collected in a solid phase. The consistency between the calculated and experimental FT-IR and FT-Raman data indicates that the B3LYP/6-31G (d, p) can generate reliable geometry and related properties of the title compounds. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution. The good agreement between the experimental and theoretical spectra allowed positive assignment of the observed vibrational absorption bands. Finally, the calculation results were applied to simulate the Raman and IR spectra of the title compounds, which show agreement with the observed spectra.
      Citation: Biosensors
      PubDate: 2017-12-26
      DOI: 10.3390/bios8010002
      Issue No: Vol. 8, No. 1 (2017)
  • Biosensors, Vol. 8, Pages 3: Electronic Tongue—A Tool for All

    • Authors: Marta Podrażka, Ewa Bączyńska, Magdalena Kundys, Paulina Jeleń, Emilia Witkowska Nery
      First page: 3
      Abstract: Electronic tongue systems are traditionally used to analyse: food products, water samples and taste masking technologies for pharmaceuticals. In principle, their applications are almost limitless, as they are able to almost completely reduce the impact of interferents and can be applied to distinguish samples of extreme complexity as for example broths from different stages of fermentation. Nevertheless, their applications outside the three principal sample types are, in comparison, rather scarce. In this review, we would like to take a closer look on what are real capabilities of electronic tongue systems, what can be achieved using mixed sensor arrays and by introduction of biosensors or molecularly imprinted polymers in the matrix. We will discuss future directions both in the sense of applications as well as system development in the ever-growing trend of low cost analysis.
      Citation: Biosensors
      PubDate: 2017-12-31
      DOI: 10.3390/bios8010003
      Issue No: Vol. 8, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 41: Biosensor Technology Reveals the Disruption
           of the Endothelial Barrier Function and the Subsequent Death of Blood
           Brain Barrier Endothelial Cells to Sodium Azide and Its Gaseous Products

    • Authors: Dan Kho, Rebecca Johnson, Simon O’Carroll, Catherine Angel, E. Scott Graham
      First page: 41
      Abstract: Herein we demonstrate the sensitive nature of human blood-brain barrier (BBB) endothelial cells to sodium azide and its gaseous product. Sodium azide is known to be acutely cytotoxic at low millimolar concentrations, hence its use as a biological preservative (e.g., in antibodies). Loss of barrier integrity was noticed in experiments using Electric Cell-substrate Impedance Sensing (ECIS) biosensor technology, to measure endothelial barrier integrity continuously in real-time. Initially the effect of sodium azide was observed as an artefact where it was present in antibodies being employed in neutralisation experiments. This was confirmed where antibody clones that were azide-free did not mediate loss of barrier function. A delayed loss of barrier function in neighbouring wells implied the influence of a liberated gaseous product. ECIS technology demonstrated that the BBB endothelial cells had a lower level of direct sensitivity to sodium azide of ~3 µM. Evidence of gaseous toxicity was consistently observed at 30 µM and above, with disrupted barrier function and cell death in neighbouring wells. We highlight the ability of this cellular biosensor technology to reveal both the direct and gaseous toxicity mediated by sodium azide. The sensitivity and temporal dimension of ECIS technology was instrumental in these observations. These findings have substantial implications for the wide use of sodium azide in biological reagents, raising issues of their application in live-cell assays and with regard to the protection of the user. This research also has wider relevance highlighting the sensitivity of brain endothelial cells to a known mitochondrial disruptor. It is logical to hypothesise that BBB endothelial dysfunction due to mitochondrial dys-regulation could have an important but underappreciated role in a range of neurological diseases.
      Citation: Biosensors
      PubDate: 2017-09-21
      DOI: 10.3390/bios7040041
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 42: A Review on Passive and Integrated
           Near-Field Microwave Biosensors

    • Authors: Subhajit Guha, Farabi Ibne Jamal, Christian Wenger
      First page: 42
      Abstract: In this paper we review the advancement of passive and integrated microwave biosensors. The interaction of microwave with biological material is discussed in this paper. Passive microwave biosensors are microwave structures, which are fabricated on a substrate and are used for sensing biological materials. On the other hand, integrated biosensors are microwave structures fabricated in standard semiconductor technology platform (CMOS or BiCMOS). The CMOS or BiCMOS sensor technology offers a more compact sensing approach which has the potential in the future for point of care testing systems. Various applications of the passive and the integrated sensors have been discussed in this review paper.
      Citation: Biosensors
      PubDate: 2017-09-23
      DOI: 10.3390/bios7040042
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 43: Raman Computational and Experimental Studies
           of Dopamine Detection

    • Authors: John Ciubuc, Kevin Bennet, Chao Qiu, Matthew Alonzo, William Durrer, Felicia Manciu
      First page: 43
      Abstract: A combined theoretical and experimental analysis of dopamine (DA) is presented in this work with the objective of achieving more accurate detection and monitoring of this neurotransmitter at very low concentrations, specific to physiological levels. Surface-enhanced Raman spectroscopy on silver nanoparticles was employed for recording DA concentrations as low as 10−11 molar. Quantum chemical density functional calculations were carried out using Gaussian-09 analytical suite software. Relatively good agreement between the simulated and experimentally determined results indicates the presence of different DA molecular forms, such as uncharged DA±, anionic DA−, and dopaminequinone. Disappearance of the strongest bands of dopamine around 750 cm−1 and 790 cm−1, which suggests its adsorption onto the metallic surface, is not only consistent with all of these DA configurations, but also provides additional information about the analyte’s redox process and voltammetric detection. On the other hand, occurrence of the abovementioned Raman lines could indicate the formation of multilayers of DA or its presence in a cationic DA+ form. Thus, through coordinated experiment and theory, valuable insights into changes observed in the vibrational signatures of this important neurotransmitter can be achieved for a better understanding of its detection at physiological levels, which is crucial if further optovoltammetric medical device development is envisioned.
      Citation: Biosensors
      PubDate: 2017-09-28
      DOI: 10.3390/bios7040043
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 44: Comparison of Sensitivity and Quantitation

    • Authors: Michihiko Nakano, Zhenhao Ding, Junya Suehiro
      First page: 44
      Abstract: In this study, we describe a microbead-based method using dielectrophoresis (DEP) for the fast detection of DNA amplified by polymerase chain reaction (PCR). This electrical method measures the change in impedance caused by DEP-trapped microbeads to which biotinylated target DNA molecules are chemically attached. Using this method, measurements can be obtained within 20 min. Currently, real-time PCR is among the most sensitive methods available for the detection of target DNA, and is often used in the diagnosis of infectious diseases. We therefore compared the quantitation and sensitivity achieved by our method to those achieved with real-time PCR. We found that the microbead DEP-based method exhibited the same detection limit as real-time PCR, although its quantitative detection range was slightly narrower at 10–105 copies/reaction compared with 10–107 copies/reaction for real-time PCR. Whereas real-time PCR requires expensive and complex instruments, as well as expertise in primer design and experimental principles, our novel method is simple to use, inexpensive, and rapid. This method could potentially detect viral and other DNAs efficiently in combination with conventional PCR.
      Citation: Biosensors
      PubDate: 2017-09-30
      DOI: 10.3390/bios7040044
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 45: CFD Modeling of Chamber Filling in a
           Micro-Biosensor for Protein Detection

    • Authors: Meiirbek Islamov, Marzhan Sypabekova, Damira Kanayeva, Luis Rojas-Solórzano
      First page: 45
      Abstract: Tuberculosis (TB) remains one of the main causes of human death around the globe. The mortality rate for patients infected with active TB goes beyond 50% when not diagnosed. Rapid and accurate diagnostics coupled with further prompt treatment of the disease is the cornerstone for controlling TB outbreaks. To reduce this burden, the existing gap between detection and treatment must be addressed, and dedicated diagnostic tools such as biosensors should be developed. A biosensor is a sensing micro-device that consists of a biological sensing element and a transducer part to produce signals in proportion to quantitative information about the binding event. The micro-biosensor cell considered in this investigation is designed to operate based on aptamers as recognition elements against Mycobacterium tuberculosis secreted protein MPT64, combined in a microfluidic-chamber with inlet and outlet connections. The microfluidic cell is a miniaturized platform with valuable advantages such as low cost of analysis with low reagent consumption, reduced sample volume, and shortened processing time with enhanced analytical capability. The main purpose of this study is to assess the flooding characteristics of the encapsulated microfluidic cell of an existing micro-biosensor using Computational Fluid Dynamics (CFD) techniques. The main challenge in the design of the microfluidic cell lies in the extraction of entrained air bubbles, which may remain after the filling process is completed, dramatically affecting the performance of the sensing element. In this work, a CFD model was developed on the platform ANSYS-CFX using the finite volume method to discretize the domain and solving the Navier–Stokes equations for both air and water in a Eulerian framework. Second-order space discretization scheme and second-order Euler Backward time discretization were used in the numerical treatment of the equations. For a given inlet–outlet diameter and dimensions of an in-house built cell chamber, different inlet liquid flow rates were explored to determine an appropriate flow condition to guarantee an effective venting of the air while filling the chamber. The numerical model depicted free surface waves as promoters of air entrainment that ultimately may explain the significant amount of air content in the chamber observed in preliminary tests after the filling process is completed. Results demonstrated that for the present design, against the intuition, the chamber must be filled with liquid at a modest flow rate to minimize free surface waviness during the flooding stage of the chamber.
      Citation: Biosensors
      PubDate: 2017-10-03
      DOI: 10.3390/bios7040045
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 46: Development and Bioanalytical Applications
           of a White Light Reflectance Spectroscopy Label-Free Sensing Platform

    • Authors: Georgios Koukouvinos, Panagiota Petrou, Dimitrios Goustouridis, Konstantinos Misiakos, Sotirios Kakabakos, Ioannis Raptis
      First page: 46
      Abstract: The development of a sensing platform based on white light reflectance spectroscopy (WLRS) is presented. The evolution of the system, from polymer film characterization and sensing of volatile organic compounds to biosensor for the label-free determination of either high (e.g., proteins) or low molecular weight analytes (e.g., pesticides), is described. At the same time, the passage from single to multi-analyte determinations, and from a laboratory prototype set-up to a compact device appropriate for on-site determination, is outlined. The improvements made on both the sensor and the optical set-up, and the concomitant advances in the analytical characteristics and the robustness of the assays performed with the different layouts, are also presented. Finally, the future perspectives of the system, aiming for the creation of a standalone instrument to be used by non-experts, will be discussed.
      Citation: Biosensors
      PubDate: 2017-10-13
      DOI: 10.3390/bios7040046
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 47: Electrospun Chitosan-Gelatin Biopolymer
           Composite Nanofibers for Horseradish Peroxidase Immobilization in a
           Hydrogen Peroxide Biosensor

    • Authors: Siriwan Teepoo, Phanphruk Dawan, Naris Barnthip
      First page: 47
      Abstract: A biosensor based on chitosan-gelatin composite biopolymers nanofibers is found to be effective for the immobilization of horseradish peroxidase to detect hydrogen peroxide. The biopolymer nanofibers were fabricated by an electrospining technique. Upon optimization of synthesis parameters, biopolymers nanofibers, an average of 80 nm in diameter, were obtained and were then modified on the working electrode surface. The effects of the concentration of enzyme, pH, and concentration of the buffer and the working potential on the current response of the nanofibers-modified electrode toward hydrogen peroxide were optimized to obtain the maximal current response. The results found that horseradish peroxidase immobilization on chitosan-gelatin composite biopolymer nanofibers had advantages of fast response, excellent reproducibility, high stability, and showed a linear response to hydrogen peroxide in the concentration range from 0.1 to 1.7 mM with a detection limit of 0.05 mM and exhibited high sensitivity of 44 µA∙mM−1∙cm−2. The developed system was evaluated for analysis of disinfectant samples and showed good agreement between the results obtained by the titration method without significant differences at the 0.05 significance level. The proposed strategy based on chitosan-gelatin composite biopolymer nanofibers for the immobilization of enzymes can be extended for the development of other enzyme-based biosensors.
      Citation: Biosensors
      PubDate: 2017-10-15
      DOI: 10.3390/bios7040047
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 48: Encapsulation-Stabilized, Europium
           Containing Nanoparticle as a Probe for Time-Resolved luminescence
           Detection of Cardiac Troponin I

    • Authors: Ka Ram Kim, Yong Duk Han, Hyeong Jin Chun, Kyung Won Lee, Dong-Ki Hong, Kook-Nyung Lee, Hyun C. Yoon
      First page: 48
      Abstract: The use of a robust optical signaling probe with a high signal-to-noise ratio is important in the development of immunoassays. Lanthanide chelates are a promising material for this purpose, which provide time-resolved luminescence (TRL) due to their large Stokes shift and long luminescence lifetime. From this, they have attracted considerable interest in the in vitro diagnostics field. However, the direct use of lanthanide chelates is limited because their luminescent signal can be easily affected by various quenchers. To overcome this drawback, strategies that rely on the entrapment of lanthanide chelates inside nanoparticles, thereby enabling the protection of the lanthanide chelate from water, have been reported. However, the poor stability of the lanthanide-entrapped nanoparticles results in a significant fluctuation in TRL signal intensity, and this still remains a challenging issue. To address this, we have developed a Lanthanide chelate-Encapsulated Silica Nano Particle (LESNP) as a new immunosensing probe. In this approach, the lanthanide chelate is covalently crosslinked within the silane monomer during the silica nanoparticle formation. The resulting LESNP is physically stable and retains TRL properties of the parent lanthanide chelate. Using the probe, a highly sensitive, sandwich-based TRL immunoassay for the cardiac troponin I was conducted, exhibiting a limit of detection of 48 pg/mL. On the basis of the features of the LESNP such as TRL signaling capability, stability, and the ease of biofunctionalization, we expect that the LESNP can be widely applied in the development of TRL-based immunosensing.
      Citation: Biosensors
      PubDate: 2017-10-18
      DOI: 10.3390/bios7040048
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 49: Strategies Using Bio-Layer Interferometry
           Biosensor Technology for Vaccine Research and Development

    • Authors: Rejane Petersen
      First page: 49
      Abstract: Bio-layer interferometry (BLI) real-time, label-free technology has greatly contributed to advances in vaccine research and development. BLI Octet platforms offer high-throughput, ease of use, reliability, and high precision analysis when compared with common labeling techniques. Many different strategies have been used to immobilize the pathogen or host molecules on BLI biosensors for real-time kinetics and affinity analysis, quantification, or high-throughput titer. These strategies can be used in multiple applications and shed light onto the structural and functional aspects molecules play during pathogen-host interactions. They also provide crucial information on how to achieve protection. This review summarizes some key BLI strategies used in human vaccine research and development.
      Citation: Biosensors
      PubDate: 2017-10-31
      DOI: 10.3390/bios7040049
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 50: An Electrochemical Enzyme Biosensor for
           3-Hydroxybutyrate Detection Using Screen-Printed Electrodes Modified by
           Reduced Graphene Oxide and Thionine

    • Authors: Gonzalo Martínez-García, Elena Pérez-Julián, Lourdes Agüí, Naomí Cabré, Jorge Joven, Paloma Yáñez-Sedeño, José Manuel Pingarrón
      First page: 50
      Abstract: A biosensor for 3-hydroxybutyrate (3-HB) involving immobilization of the enzyme 3-hydroxybutyrate dehydrogenase onto a screen-printed carbon electrode modified with reduced graphene oxide (GO) and thionine (THI) is reported here. After addition of 3-hydroxybutyrate or the sample in the presence of NAD+ cofactor, the generated NADH could be detected amperometrically at 0.0 V vs. Ag pseudo reference electrode. Under the optimized experimental conditions, a calibration plot for 3-HB was constructed showing a wide linear range between 0.010 and 0.400 mM 3-HB which covers the clinically relevant levels for diluted serum samples. In addition, a limit of detection of 1.0 µM, much lower than that reported using other biosensors, was achieved. The analytical usefulness of the developed biosensor was demonstrated via application to spiked serum samples.
      Citation: Biosensors
      PubDate: 2017-11-11
      DOI: 10.3390/bios7040050
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 51: Review on SERS of Bacteria

    • Authors: Pamela Mosier-Boss
      First page: 51
      Abstract: Surface enhanced Raman spectroscopy (SERS) has been widely used for chemical detection. Moreover, the inherent richness of the spectral data has made SERS attractive for use in detecting biological materials, including bacteria. This review discusses methods that have been used to obtain SERS spectra of bacteria. The kinds of SERS substrates employed to obtain SERS spectra are discussed as well as how bacteria interact with silver and gold nanoparticles. The roll of capping agents on Ag/Au NPs in obtaining SERS spectra is examined as well as the interpretation of the spectral data.
      Citation: Biosensors
      PubDate: 2017-11-13
      DOI: 10.3390/bios7040051
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 52: Ramanomics: New Omics Disciplines Using
           Micro Raman Spectrometry with Biomolecular Component Analysis for
           Molecular Profiling of Biological Structures

    • Authors: Andrey Kuzmin, Artem Pliss, Paras Prasad
      First page: 52
      Abstract: Modern instrumentation for Raman microspectroscopy and current techniques in analysis of spectral data provide new opportunities to study molecular interactions and dynamics at subcellular levels in biological systems. Implementation of biomolecular component analysis (BCA) to microRaman spectrometry provides basis for the emergence of Ramanomics, a new biosensing discipline with unprecedented capabilities to measure concentrations of distinct biomolecular groups in live cells and organelles. Here we review the combined use of microRaman-BCA techniques to probe absolute concentrations of proteins, DNA, RNA and lipids in single organelles of live cells. Assessing biomolecular concentration profiles of organelles at the single cell level provides a physiologically relevant set of biomarkers for cellular heterogeneity. In addition, changes to an organelle’s biomolecular concentration profile during a cellular transformation, whether natural, drug induced or disease manifested, can provide molecular insight into the nature of the cellular process.
      Citation: Biosensors
      PubDate: 2017-11-15
      DOI: 10.3390/bios7040052
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 53: Central [CNS] and Peripheral [Gastric
           Tissue] Selective Monitoring of Somatostatin (SRIF) with Micro-Sensor and
           Voltammetry in Rats: Influence of Growth Factors (GH, EGF)

    • Authors: Francesco Crespi
      First page: 53
      Abstract: Somatostatin (SRIF) is widely distributed throughout the body, and regulates the endocrine system via interactions with various hormones, including the pituitary growth hormone, the thyroid stimulating hormone and the majority of the hormones of the gastrointestinal tract. SRIF is present in the central nervous system (CNS), where it affects rates of neurotransmission, and is also reported to be active in the intestinal tract, with evidence that stressed rats present a significant decrease in antral somatostatin-like immunoreactivity (SLI). Analysis of SRIF has mainly been carried out by means of radioimmunoassay methods. Here, we propose the use of an electrochemical method, such as voltammetry, applied with carbon-based sensors and, in particular, the combination of differential pulse voltammetry with treated carbon fiber micro electrodes (DPV-µCFE) to facilitate the analysis of such peptidergic electro active hormones in the rat striatum and gastric tissue; the effect of growth hormone (GH) and epidermal growth factor (EGF), in particular, upon the SRIF signal has been studied in such tissues.
      Citation: Biosensors
      PubDate: 2017-11-17
      DOI: 10.3390/bios7040053
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 54: A Gal-MµS Device to Evaluate Cell Migratory
           Response to Combined Galvano-Chemotactic Fields

    • Authors: Shawn Mishra, Maribel Vazquez
      First page: 54
      Abstract: Electric fields have been studied extensively in biomedical engineering (BME) for numerous regenerative therapies. Recent studies have begun to examine the biological effects of electric fields in combination with other environmental cues, such as tissue-engineered extracellular matrices (ECM), chemical gradient profiles, and time-dependent temperature gradients. In the nervous system, cell migration driven by electrical fields, or galvanotaxis, has been most recently studied in transcranial direct stimulation (TCDS), spinal cord repair and tumor treating fields (TTF). The cell migratory response to galvano-combinatory fields, such as magnetic fields, chemical gradients, or heat shock, has only recently been explored. In the visual system, restoration of vision via cellular replacement therapies has been limited by low numbers of motile cells post-transplantation. Here, the combinatory application of electrical fields with other stimuli to direct cells within transplantable biomaterials and/or host tissues has been understudied. In this work, we developed the Gal-MµS device, a novel microfluidics device capable of examining cell migratory behavior in response to single and combinatory stimuli of electrical and chemical fields. The formation of steady-state, chemical concentration gradients and electrical fields within the Gal-MµS were modeled computationally and verified experimentally within devices fabricated via soft lithography. Further, we utilized real-time imaging within the device to capture cell trajectories in response to electric fields and chemical gradients, individually, as well as in combinatory fields of both. Our data demonstrated that neural cells migrated longer distances and with higher velocities in response to combined galvanic and chemical stimuli than to either field individually, implicating cooperative behavior. These results reveal a biological response to galvano-chemotactic fields that is only partially understood, as well as point towards novel migration-targeted treatments to improve cell-based regenerative therapies.
      Citation: Biosensors
      PubDate: 2017-11-21
      DOI: 10.3390/bios7040054
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 55: A Radar-Based Smart Sensor for Unobtrusive
           Elderly Monitoring in Ambient Assisted Living Applications

    • Authors: Giovanni Diraco, Alessandro Leone, Pietro Siciliano
      First page: 55
      Abstract: Continuous in-home monitoring of older adults living alone aims to improve their quality of life and independence, by detecting early signs of illness and functional decline or emergency conditions. To meet requirements for technology acceptance by seniors (unobtrusiveness, non-intrusiveness, and privacy-preservation), this study presents and discusses a new smart sensor system for the detection of abnormalities during daily activities, based on ultra-wideband radar providing rich, not privacy-sensitive, information useful for sensing both cardiorespiratory and body movements, regardless of ambient lighting conditions and physical obstructions (through-wall sensing). The radar sensing is a very promising technology, enabling the measurement of vital signs and body movements at a distance, and thus meeting both requirements of unobtrusiveness and accuracy. In particular, impulse-radio ultra-wideband radar has attracted considerable attention in recent years thanks to many properties that make it useful for assisted living purposes. The proposed sensing system, evaluated in meaningful assisted living scenarios by involving 30 participants, exhibited the ability to detect vital signs, to discriminate among dangerous situations and activities of daily living, and to accommodate individual physical characteristics and habits. The reported results show that vital signs can be detected also while carrying out daily activities or after a fall event (post-fall phase), with accuracy varying according to the level of movements, reaching up to 95% and 91% in detecting respiration and heart rates, respectively. Similarly, good results were achieved in fall detection by using the micro-motion signature and unsupervised learning, with sensitivity and specificity greater than 97% and 90%, respectively.
      Citation: Biosensors
      PubDate: 2017-11-24
      DOI: 10.3390/bios7040055
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 56: Simple Screening of Listeria monocytogenes
           Based on a Fluorescence Assay via a Laminated Lab-On-Paper Chip

    • Authors: Kankanit Pisamayarom, Annop Suriyasomboon, Piyasak Chaumpluk
      First page: 56
      Abstract: Monitoring food safety is essential for protecting the health and safety of consumers. Conventional methods used are time consuming and laborious, requiring anywhere from three to seven days to obtain results. Thus, better monitoring methods are required. In this study, a laminated lab-on-paper chip was developed, and its use for the screening of ready-to-eat seafood was demonstrated. The assay on a chip was based on loop-mediated isothermal DNA amplification (LAMP) of the hly gene of Listeria monocytogenes and fluorescence signal detection via SYBR GoldTM. Overall assay processes were completed in 4.5 h., (including 3.5 h. incubation for the bacteria enrichment, direct DNA amplification with no DNA extraction, and signal detection), without relying on standard laboratory facilities. Only positive samples induced fluorescence signals on chip upon illumination with UV light (λ = 460). The method has a limit of detection of 100 copies of L. monocytogenes DNA per 50 g of sample. No cross-reactivity was observed in samples contaminated with other bacteria. On-site monitoring of the seafood products using this chip revealed that one of 30 products from low sanitation vendors (3.33%) were contaminated, and these agreed with the results of PCR. The results demonstrated a benefit of this chip assay for practical on-site monitoring.
      Citation: Biosensors
      PubDate: 2017-11-28
      DOI: 10.3390/bios7040056
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 57: Study of SH-SY5Y Cancer Cell Response to
           Treatment with Polyphenol Extracts Using FT-IR Spectroscopy

    • Authors: Valerio Ricciardi, Marianna Portaccio, Simona Piccolella, Lorenzo Manti, Severina Pacifico, Maria Lepore
      First page: 57
      Abstract: Plant polyphenols are important components of human diet and a number of them are considered to possess chemo-preventive and therapeutic properties against cancer. They are recognized as naturally occurring antioxidants, but also as pro-oxidant, pro-apoptotic, or chromosomal aberrations inducers, depending on their concentration and/or the stage of cell-cycle of the cells with which they interact. For these reasons, particular interest is devoted to knowing the total effects of polyphenols on the cell cycle and metabolism. Fourier-Transform Infrared (FT-IR) spectroscopy thanks to its ability in analyzing cells at a molecular level can be particularly useful in investigating the biochemical changes induced in protein, nucleic acid, lipid, and carbohydrate content of cells by means of polyphenols administration. Spectroscopic analysis was performed on in vitro human SH-SY5Y neuroblastoma cells that were exposed to different doses of a cherry derived polyphenol extract. The infrared spectra that were obtained from unexposed and exposed cells show significant differences that can be helpful in order to understand the cells-polyphenols interaction.
      Citation: Biosensors
      PubDate: 2017-11-30
      DOI: 10.3390/bios7040057
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 58: An All-Glass Microfluidic Network with
           Integrated Amorphous Silicon Photosensors for on-Chip Monitoring of
           Enzymatic Biochemical Assay

    • Authors: Francesca Costantini, Roald Tiggelaar, Riccardo Salvio, Marco Nardecchia, Stefan Schlautmann, Cesare Manetti, Han Gardeniers, Giampiero de Cesare, Domenico Caputo, Augusto Nascetti
      First page: 58
      Abstract: A lab-on-chip system, integrating an all-glass microfluidics and on-chip optical detection, was developed and tested. The microfluidic network is etched in a glass substrate, which is then sealed with a glass cover by direct bonding. Thin film amorphous silicon photosensors have been fabricated on the sealed microfluidic substrate preventing the contamination of the micro-channels. The microfluidic network is then made accessible by opening inlets and outlets just prior to the use, ensuring the sterility of the device. The entire fabrication process relies on conventional photolithographic microfabrication techniques and is suitable for low-cost mass production of the device. The lab-on-chip system has been tested by implementing a chemiluminescent biochemical reaction. The inner channel walls of the microfluidic network are chemically functionalized with a layer of polymer brushes and horseradish peroxidase is immobilized into the coated channel. The results demonstrate the successful on-chip detection of hydrogen peroxide down to 18 μM by using luminol and 4-iodophenol as enhancer agent.
      Citation: Biosensors
      PubDate: 2017-12-05
      DOI: 10.3390/bios7040058
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 59: Cutting Edge Methods for Non-Invasive
           Disease Diagnosis Using E-Tongue and E-Nose Devices

    • Authors: Jessica Fitzgerald, Hicham Fenniri
      First page: 59
      Abstract: Biomimetic cross-reactive sensor arrays (B-CRSAs) have been used to detect and diagnose a wide variety of diseases including metabolic disorders, mental health diseases, and cancer by analyzing both vapor and liquid patient samples. Technological advancements over the past decade have made these systems selective, sensitive, and affordable. To date, devices for non-invasive and accurate disease diagnosis have seen rapid improvement, suggesting a feasible alternative to current standards for medical diagnostics. This review provides an overview of the most recent B-CRSAs for diagnostics (also referred to electronic noses and tongues in the literature) and an outlook for future technological development.
      Citation: Biosensors
      PubDate: 2017-12-07
      DOI: 10.3390/bios7040059
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 60: Spontaneous Charge Generation in Flowing
           Albumin Solutions at 35 °C and 38 °C

    • Authors: Yuri Ivanov, Andrey Kozlov, Rafael Galiullin, Ekaterina Kolesanova, Tatyana Pleshakova
      First page: 60
      Abstract: The time dependence of a charge accumulation in a 10−15 M albumin solution, flowing through a measuring cell of an analytical flow system injector, had a nonlinear character under certain conditions, within a human physiological temperature range. Sharp charge increases depended on albumin concentration. This effect must be taken into consideration when generating models that describe electrokinetic phenomena in flowing protein solutions and when developing analytical flow systems for the registration of biomolecules in low concentration ranges.
      Citation: Biosensors
      PubDate: 2017-12-11
      DOI: 10.3390/bios7040060
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 61: Fluorescent and Colorimetric Electrospun
           Nanofibers for Heavy-Metal Sensing

    • Authors: Idelma Terra, Luiza Mercante, Rafaela Andre, Daniel Correa
      First page: 61
      Abstract: The accumulation of heavy metals in the human body and/or in the environment can be highly deleterious for mankind, and currently, considerable efforts have been made to develop reliable and sensitive techniques for their detection. Among the detection methods, chemical sensors appear as a promising technology, with emphasis on systems employing optically active nanofibers. Such nanofibers can be obtained by the electrospinning technique, and further functionalized with optically active chromophores such as dyes, conjugated polymers, carbon-based nanomaterials and nanoparticles, in order to produce fluorescent and colorimetric nanofibers. In this review we survey recent investigations reporting the use of optically active electrospun nanofibers in sensors aiming at the specific detection of heavy metals using colorimetry and fluorescence methods. The examples given in this review article provide sufficient evidence of the potential of optically electrospun nanofibers as a valid approach to fabricate highly selective and sensitive optical sensors for fast and low-cost detection of heavy metals.
      Citation: Biosensors
      PubDate: 2017-12-15
      DOI: 10.3390/bios7040061
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 62: Point-of-Care Diagnostics: Recent Advances
           and Trends

    • Authors: Sandeep Vashist
      First page: 62
      Abstract: Recent years have witnessed tremendous advances in point-of-care diagnostics (POCD), which are a result of continuous developments in biosensors, microfluidic, bioanalytical platforms, assay formats, lab-on-a-chip technologies, and complementary technologies. This special issue targets the critical advances in POCD and provides guided insights and directions for future research.
      Citation: Biosensors
      PubDate: 2017-12-18
      DOI: 10.3390/bios7040062
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 63: Fluorescence-Free Biosensor Methods in
           Detection of Food Pathogens with a Special Focus on Listeria monocytogenes

    • Authors: Rajeswaran Radhakrishnan, Palmiro Poltronieri
      First page: 63
      Abstract: Food pathogens contaminate food products that allow their growth on the shelf and also under refrigerated conditions. Therefore, it is of utmost importance to lower the limit of detection (LOD) of the method used and to obtain the results within hours to few days. Biosensor methods exploit the available technologies to individuate and provide an approximate quantification of the bacteria present in a sample. The main bottleneck of these methods depends on the aspecific binding to the surfaces and on a change in sensitivity when bacteria are in a complex food matrix with respect to bacteria in a liquid food sample. In this review, we introduce surface plasmon resonance (SPR), new advancements in SPR techniques, and electrochemical impedance spectroscopy (EIS), as fluorescence-free biosensing technologies for detection of L. monocytogenes in foods. The application of the two methods has facilitated L. monocytogenes detection with LOD of 1 log CFU/mL. Further advancements are envisaged through the combination of biosensor methods with immunoseparation of bacteria from larger volumes, application of lab-on-chip technologies, and EIS sensing methods for multiplex pathogen detection. Validation efforts are being conducted to demonstrate the robustness of detection, reproducibility and variability in multi-site installations.
      Citation: Biosensors
      PubDate: 2017-12-20
      DOI: 10.3390/bios7040063
      Issue No: Vol. 7, No. 4 (2017)
  • Biosensors, Vol. 7, Pages 24: Optical Tracking and Digital Quantification
           of Beating Behavior in Bioengineered Human Cardiac Organoids

    • Authors: Mahesh Devarasetty, Steven Forsythe, Thomas Shupe, Shay Soker, Colin Bishop, Anthony Atala, Aleksander Skardal
      First page: 24
      Abstract: Organoid and organ-on-a-chip technologies are rapidly advancing towards deployment for drug and toxicology screening applications. Liver and cardiac toxicities account for the majority of drug candidate failures in human trials. Liver toxicity generally produces liver cell death, while cardiac toxicity causes adverse changes in heart beat kinetics. In traditional 2D cultures, beating kinetics can be measured by electrode arrays, but in some 3D constructs, quantifying beating kinetics can be more challenging. For example, real time measurements of calcium flux or contractile forces are possible, yet rather complex. In this communication article, we demonstrate a simple sensing system based on software code that optically analyzes video capture files of beating cardiac organoids, translates these files in representations of moving pixels, and quantifies pixel movement activity over time to generate beat kinetic plots. We demonstrate this system using bioengineered cardiac organoids under baseline and drug conditions. This technology offers a non-invasive, low-cost, and incredibly simple method for tracking and quantifying beating behavior in cardiac organoids and organ-on-a-chip systems for drug and toxicology screening.
      PubDate: 2017-06-23
      DOI: 10.3390/bios7030024
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 25: Detection of Lipid and Amphiphilic
           Biomarkers for Disease Diagnostics

    • Authors: Jessica Kubicek-Sutherland, Dung Vu, Heather Mendez, Shailja Jakhar, Harshini Mukundan
      First page: 25
      Abstract: Rapid diagnosis is crucial to effectively treating any disease. Biological markers, or biomarkers, have been widely used to diagnose a variety of infectious and non-infectious diseases. The detection of biomarkers in patient samples can also provide valuable information regarding progression and prognosis. Interestingly, many such biomarkers are composed of lipids, and are amphiphilic in biochemistry, which leads them to be often sequestered by host carriers. Such sequestration enhances the difficulty of developing sensitive and accurate sensors for these targets. Many of the physiologically relevant molecules involved in pathogenesis and disease are indeed amphiphilic. This chemical property is likely essential for their biological function, but also makes them challenging to detect and quantify in vitro. In order to understand pathogenesis and disease progression while developing effective diagnostics, it is important to account for the biochemistry of lipid and amphiphilic biomarkers when creating novel techniques for the quantitative measurement of these targets. Here, we review techniques and methods used to detect lipid and amphiphilic biomarkers associated with disease, as well as their feasibility for use as diagnostic targets, highlighting the significance of their biochemical properties in the design and execution of laboratory and diagnostic strategies. The biochemistry of biological molecules is clearly relevant to their physiological function, and calling out the need for consideration of this feature in their study, and use as vaccine, diagnostic and therapeutic targets is the overarching motivation for this review.
      PubDate: 2017-07-04
      DOI: 10.3390/bios7030025
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 26: Lipid Bilayer Membrane in a Silicon Based
           Micron Sized Cavity Accessed by Atomic Force Microscopy and
           Electrochemical Impedance Spectroscopy

    • Authors: Muhammad Khan, Noura Dosoky, Darayas Patel, Jeffrey Weimer, John Williams
      First page: 26
      Abstract: Supported lipid bilayers (SLBs) are widely used in biophysical research to probe the functionality of biological membranes and to provide diagnoses in high throughput drug screening. Formation of SLBs at below phase transition temperature (Tm) has applications in nano-medicine research where low temperature profiles are required. Herein, we report the successful production of SLBs at above—as well as below—the Tm of the lipids in an anisotropically etched, silicon-based micro-cavity. The Si-based cavity walls exhibit controlled temperature which assist in the quick and stable formation of lipid bilayer membranes. Fusion of large unilamellar vesicles was monitored in real time in an aqueous environment inside the Si cavity using atomic force microscopy (AFM), and the lateral organization of the lipid molecules was characterized until the formation of the SLBs. The stability of SLBs produced was also characterized by recording the electrical resistance and the capacitance using electrochemical impedance spectroscopy (EIS). Analysis was done in the frequency regime of 10−2–105 Hz at a signal voltage of 100 mV and giga-ohm sealed impedance was obtained continuously over four days. Finally, the cantilever tip in AFM was utilized to estimate the bilayer thickness and to calculate the rupture force at the interface of the tip and the SLB. We anticipate that a silicon-based, micron-sized cavity has the potential to produce highly-stable SLBs below their Tm. The membranes inside the Si cavity could last for several days and allow robust characterization using AFM or EIS. This could be an excellent platform for nanomedicine experiments that require low operating temperatures.
      PubDate: 2017-07-05
      DOI: 10.3390/bios7030026
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 27: A Label-Free and Ultrasensitive Immunosensor
           for Detection of Human Chorionic Gonadotrophin Based on Graphene FETs

    • Authors: Kamrul Islam, Ahmed Suhail, Genhua Pan
      First page: 27
      Abstract: We report on a label-free immunosensor based on graphene field effect transistors (G-FETs) for the ultrasensitive detection of Human Chorionic Gonadotrophin (hCG), as an indicator of pregnancy and related disorders, such as actopic pregnancy, choriocarcinoma and orchic teratoma. Pyrene based bioactive ester was non-covalently anchored onto the graphene channel in order to retain the sp2 lattice. The G-FET transfer characteristics showed repeatable and reliable responses in all surface modifying steps using a direct current (DC) readout system. The hCG concentration gradient showed a detection limit of ~1 pg·mL−1. The proposed method facilitates the cost-effective and viable production of graphene point-of-care devices for clinical diagnosis.
      PubDate: 2017-07-12
      DOI: 10.3390/bios7030027
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 28: Development of an Immunosensor for PfHRP 2
           as a Biomarker for Malaria Detection

    • Authors: Aver Hemben, Jon Ashley, Ibtisam Tothill
      First page: 28
      Abstract: Plasmodium falciparum histidine-rich protein 2 (PfHRP 2) was selected in this work as the biomarker for the detection and diagnosis of malaria. An enzyme-linked immunosorbent assay (ELISA) was first developed to evaluate the immunoreagent’s suitability for the sensor’s development. A gold-based sensor with an integrated counter and an Ag/AgCl reference electrode was first selected and characterised and then used to develop the immunosensor for PfHRP 2, which enables a low cost, easy to use, and sensitive biosensor for malaria diagnosis. The sensor was applied to immobilise the anti-PfHRP 2 monoclonal antibody as the capture receptor. A sandwich ELISA assay format was constructed using horseradish peroxidase (HRP) as the enzyme label, and the electrochemical signal was generated using a 3, 3′, 5, 5′tetramethyl-benzidine dihydrochloride (TMB)/H2O2 system. The performance of the assay and the sensor were optimised and characterised, achieving a PfHRP 2 limit of detection (LOD) of 2.14 ng·mL−1 in buffer samples and 2.95 ng∙mL−1 in 100% spiked serum samples. The assay signal was then amplified using gold nanoparticles conjugated detection antibody-enzyme and a detection limit of 36 pg∙mL−1 was achieved in buffer samples and 40 pg∙mL−1 in serum samples. This sensor format is ideal for malaria detection and on-site analysis as a point-of-care device (POC) in resource-limited settings where the implementation of malaria diagnostics is essential in control and elimination efforts.
      Citation: Biosensors
      PubDate: 2017-07-18
      DOI: 10.3390/bios7030028
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 29: In Vitro Quantified Determination of
           β-Amyloid 42 Peptides, a Biomarker of Neuro-Degenerative Disorders, in
           PBS and Human Serum Using a Simple, Cost-Effective Thin Gold Film

    • Authors: Yifan Dai, Alireza Molazemhosseini, Chung Liu
      First page: 29
      Abstract: A simple in vitro biosensor for the detection of β-amyloid 42 in phosphate-buffered saline (PBS) and undiluted human serum was fabricated and tested based on our platform sensor technology. The bio-recognition mechanism of this biosensor was based on the effect of the interaction between antibody and antigen of β-amyloid 42 to the redox couple probe of K4Fe(CN)6 and K3Fe(CN)6. Differential pulse voltammetry (DPV) served as the transduction mechanism measuring the current output derived from the redox coupling reaction. The biosensor was a three-electrode electrochemical system, and the working and counter electrodes were 50 nm thin gold film deposited by a sputtering technique. The reference electrode was a thick-film printed Ag/AgCl electrode. Laser ablation technique was used to define the size and structure of the biosensor. Cost-effective roll-to-roll manufacturing process was employed in the fabrication of the biosensor, making it simple and relatively inexpensive. Self-assembled monolayers (SAM) of 3-Mercaptopropionic acid (MPA) was employed to covalently immobilize the thiol group on the gold working electrode. A carbodiimide conjugation approach using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N–hydroxysuccinimide (NHS) was undertaken for cross-linking antibody of β-amyloid 42 to the carboxylic groups on one end of the MPA. The antibody concentration of β-amyloid 42 used was 18.75 µg/mL. The concentration range of β-amyloid 42 in this study was from 0.0675 µg/mL to 0.5 µg/mL for both PBS and undiluted human serum. DPV measurements showed excellent response in this antigen concentration range. Interference study of this biosensor was carried out in the presence of Tau protein antigen. Excellent specificity of this β-amyloid 42 biosensor was demonstrated without interference from other species, such as T-tau protein.
      Citation: Biosensors
      PubDate: 2017-07-20
      DOI: 10.3390/bios7030029
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 30: Point-of-Care-Testing in Acute Stroke
           Management: An Unmet Need Ripe for Technological Harvest

    • Authors: Dorin Harpaz, Evgeni Eltzov, Raymond C.S. Seet, Robert S. Marks, Alfred I.Y. Tok
      First page: 30
      Abstract: Stroke, the second highest leading cause of death, is caused by an abrupt interruption of blood to the brain. Supply of blood needs to be promptly restored to salvage brain tissues from irreversible neuronal death. Existing assessment of stroke patients is based largely on detailed clinical evaluation that is complemented by neuroimaging methods. However, emerging data point to the potential use of blood-derived biomarkers in aiding clinical decision-making especially in the diagnosis of ischemic stroke, triaging patients for acute reperfusion therapies, and in informing stroke mechanisms and prognosis. The demand for newer techniques to deliver individualized information on-site for incorporation into a time-sensitive work-flow has become greater. In this review, we examine the roles of a portable and easy to use point-of-care-test (POCT) in shortening the time-to-treatment, classifying stroke subtypes and improving patient’s outcome. We first examine the conventional stroke management workflow, then highlight situations where a bedside biomarker assessment might aid clinical decision-making. A novel stroke POCT approach is presented, which combines the use of quantitative and multiplex POCT platforms for the detection of specific stroke biomarkers, as well as data-mining tools to drive analytical processes. Further work is needed in the development of POCTs to fulfill an unmet need in acute stroke management.
      Citation: Biosensors
      PubDate: 2017-08-03
      DOI: 10.3390/bios7030030
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 31: An Affordable Microsphere-Based Device for
           Visual Assessment of Water Quality

    • Authors: Azra Rajwani, Brendon Restall, Nathan J. Muller, Scott Roebuck, Stephanie M. Willerth
      First page: 31
      Abstract: This work developed a prototype of an affordable, long-term water quality detection device that provides a visual readout upon detecting bacterial contamination. This device prototype consists of: (1) enzyme-releasing microspheres that lyse bacteria present in a sample, (2) microspheres that release probes that bind the DNA of the lysed bacteria, and (3) a detector region consisting of gold nanoparticles. The probes bind bacterial DNA, forming complexes. These complexes induce aggregation of the gold nanoparticles located in the detector region. The nanoparticle aggregation process causes a red to blue color change, providing a visual indicator of contamination being detected. Our group fabricated and characterized microspheres made of poly (ε-caprolactone) that released lysozyme (an enzyme that degrades bacterial cell walls) and hairpin DNA probes that bind to regions of the Escherichia coli genome over a 28-day time course. The released lysozyme retained its ability to lyse bacteria. We then showed that combining these components with gold nanoparticles followed by exposure to an E. coli-contaminated water sample (concentrations tested—106 and 108 cells/mL) resulted in a dramatic red to blue color change. Overall, this device represents a novel low-cost system for long term detection of bacteria in a water supply and other applications.
      Citation: Biosensors
      PubDate: 2017-08-05
      DOI: 10.3390/bios7030031
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 32: A Novel Surface Plasmon Resonance Biosensor
           for the Rapid Detection of Botulinum Neurotoxins

    • Authors: Kruti Patel, Shmuel Halevi, Paul Melman, John Schwartz, Shuowei Cai, Bal Singh
      First page: 32
      Abstract: Botulinum neurotoxins (BoNTs) are Category A agents on the NIAID (National Institute of Allergy and Infectious Diseases) priority pathogen list owing to their extreme toxicity and the relative ease of production. These deadly toxins, in minute quantities (estimated human i.v. lethal dose LD50 of 1–2 ng/kg body weight), cause fatal flaccid paralysis by blocking neurotransmitter release. The current gold standard detection method, the mouse-bioassay, often takes days to confirm botulism. Furthermore, there are no effective antidotes known to reverse the symptoms of botulism, and as a result, patients with severe botulism often require meticulous care during the prolonged paralytic illness. To combat potential bio-terrorism incidents of botulinum neurotoxins, their rapid detection is paramount. Surface plasmon resonance (SPR) is a very sensitive technique to examine bio-molecular interactions. The label-free, real-time analysis, with high sensitivity and low sample consumption makes this technology particularly suitable for detection of the toxin. In this study, we demonstrated the feasibility in an assay with a newly designed SPR instrument for the rapid detection of botulinum neurotoxins. The LOD (limit of detection) of the Newton Photonics (NP) SPR based assay is 6.76 pg/mL for Botulinum Neurotoxin type A Light Chain (BoNT/A LC). We established that the detection sensitivity of the system is comparable to the traditional mouse LD50 bioassay in BoNT/A using this SPR technology.
      Citation: Biosensors
      PubDate: 2017-08-07
      DOI: 10.3390/bios7030032
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 33: Bloch Surface Waves Biosensors for High
           Sensitivity Detection of Soluble ERBB2 in a Complex Biological Environment

    • Authors: Alberto Sinibaldi, Camilla Sampaoli, Norbert Danz, Peter Munzert, Frank Sonntag, Fabio Centola, Agostino Occhicone, Elisa Tremante, Patrizio Giacomini, Francesco Michelotti
      First page: 33
      Abstract: We report on the use of one-dimensional photonic crystals to detect clinically relevant concentrations of the cancer biomarker ERBB2 in cell lysates. Overexpression of the ERBB2 protein is associated with aggressive breast cancer subtypes. To detect soluble ERBB2, we developed an optical set-up which operates in both label-free and fluorescence modes. The detection approach makes use of a sandwich assay, in which the one-dimensional photonic crystals sustaining Bloch surface waves are modified with monoclonal antibodies, in order to guarantee high specificity during the biological recognition. We present the results of exemplary protein G based label-free assays in complex biological matrices, reaching an estimated limit of detection of 0.5 ng/mL. On-chip and chip-to-chip variability of the results is addressed too, providing repeatability rates. Moreover, results on fluorescence operation demonstrate the capability to perform high sensitive cancer biomarker assays reaching a resolution of 0.6 ng/mL, without protein G assistance. The resolution obtained in both modes meets international guidelines and recommendations (15 ng/mL) for ERBB2 quantification assays, providing an alternative tool to phenotype and diagnose molecular cancer subtypes.
      Citation: Biosensors
      PubDate: 2017-08-17
      DOI: 10.3390/bios7030033
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 34: Thermal Response Analysis of Phospholipid
           Bilayers Using Ellipsometric Techniques

    • Authors: Carmen González-Henríquez, Vanessa Villegas-Opazo, Dallits Sagredo-Oyarce, Mauricio Sarabia-Vallejos, Claudio Terraza
      First page: 34
      Abstract: Biomimetic planar artificial membranes have been widely studied due to their multiple applications in several research fields. Their humectation and thermal response are crucial for reaching stability; these characteristics are related to the molecular organization inside the bilayer, which is affected by the aliphatic chain length, saturations, and molecule polarity, among others. Bilayer stability becomes a fundamental factor when technological devices are developed—like biosensors—based on those systems. Thermal studies were performed for different types of phosphatidylcholine (PC) molecules: two pure PC bilayers and four binary PC mixtures. These analyses were carried out through the detection of slight changes in their optical and structural parameters via Ellipsometry and Surface Plasmon Resonance (SPR) techniques. Phospholipid bilayers were prepared by Langmuir-Blodgett technique and deposited over a hydrophilic silicon wafer. Their molecular inclination degree, mobility, and stability of the different phases were detected and analyzed through bilayer thickness changes and their optical phase-amplitude response. Results show that certain binary lipid mixtures—with differences in its aliphatic chain length—present a co-existence of two thermal responses due to non-ideal mixing.
      Citation: Biosensors
      PubDate: 2017-08-18
      DOI: 10.3390/bios7030034
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 35: A Novel Impedance Biosensor for Measurement
           of Trans-Epithelial Resistance in Cells Cultured on Nanofiber Scaffolds

    • Authors: Robert Schramm, Matthew Koslow, Deirdre Nelson, Melinda Larsen, James Castracane
      First page: 35
      Abstract: Nanofibrous scaffolds provide high surface area for cell attachment, and resemble the structure of the collagen fibers which naturally occur in the basement membrane and extracellular matrix. A label free and non-destructive method of assessing the interaction of cell tissue and scaffolds aids in the ability to discern the effective quality and magnitude of any scaffold modifications. Impedance cell spectroscopy is a biosensing method that employs a functional approach to assessing the cell monolayer. The electrical impedance barrier function of a cell monolayer represents the level of restriction to diffusion of charged species between all adjacent cells across an entire contiguous cellular monolayer. The impedance signals from many individual paracellular pathways contribute to the bulk measurement of the whole monolayer barrier function. However, the scaffold substrate must be entirely porous in order to be used with electrochemical cell impedance spectroscopy (ECIS) and cells must be closely situated to the electrodes. For purposes of evaluating cell-scaffold constructs for tissue engineering, non-invasive evaluation of cell properties while seeded on scaffolds is critical. A Transwell-type assay makes a measurement across a semi-permeable membrane, using electrodes placed on opposing sides of the membrane immersed in fluid. It was found that by suspending a nanofiber scaffold across a Transwell aperture, it is possible to integrate a fully functional nanofiber tissue scaffold with the ECIS Transwell apparatus. Salivary epithelial cells were grown on the nanofiber scaffolds and tight junction formation was evaluated using ECIS measurements in parallel with immunostaining and confocal imaging. The trans-epithelial resistance increased coordinate with cell coverage, culminating with a cell monolayer, at which point the tight junction proteins assemble and strengthen, reaching the peak signal. These studies demonstrate that ECIS can be used to evaluate tight junction formation in cells grown on nanofiber scaffolds and on effects of scaffold conditions on cells, thus providing useful biological feedback to inform superior scaffold designs.
      Citation: Biosensors
      PubDate: 2017-08-31
      DOI: 10.3390/bios7030035
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 36: A Rationally Designed Reversible
           ‘Turn-Off’ Sensor for Glutathione

    • Authors: Sabrina Heng, Xiaozhou Zhang, Jinxin Pei, Andrew Abell
      First page: 36
      Abstract: γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with diseases. Existing fluorescence-based chemosensors for GSH acts as irreversible reaction-based probes that exhibit a maximum fluorescence (‘turn-on’) once the reaction is complete, regardless of the actual concentration of GSH. A reversible, reaction-based ‘turn-off’ probe (1) is reported here to sense the decreasing levels of GSH, a situation known to occur at the onset of various diseases. The more fluorescent merocyanine (MC) isomer of 1 exists in aqueous solution and this reacts with GSH to induce formation of the ring-closed spiropyran (SP) isomer, with a measurable decrease in absorbance and fluorescence (‘turn-off’). Sensor 1 has good aqueous solubility and shows an excellent selectivity for GSH over other biologically relevant metal ions and aminothiol analytes. The sensor permeates HEK 293 cells and an increase in fluorescence is observed on adding buthionine sulfoximine, an inhibitor of GSH synthesis.
      Citation: Biosensors
      PubDate: 2017-09-06
      DOI: 10.3390/bios7030036
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 37: Silicon Integrated Dual-Mode Interferometer
           with Differential Outputs

    • Authors: Niklas Hoppe, Pascal Scheck, Rami Sweidan, Philipp Diersing, Lotte Rathgeber, Wolfgang Vogel, Benjamin Riegger, Alexander Southan, Manfred Berroth
      First page: 37
      Abstract: The dual-mode interferometer (DMI) is an attractive alternative to Mach-Zehnder interferometers for sensor purposes, achieving sensitivities to refractive index changes close to state-of-the-art. Modern designs on silicon-on-insulator (SOI) platforms offer thermally stable and compact devices with insertion losses of less than 1 dB and high extinction ratios. Compact arrays of multiple DMIs in parallel are easy to fabricate due to the simple structure of the DMI. In this work, the principle of operation of an integrated DMI with differential outputs is presented which allows the unambiguous phase shift detection with a single wavelength measurement, rather than using a wavelength sweep and evaluating the optical output power spectrum. Fluctuating optical input power or varying attenuation due to different analyte concentrations can be compensated by observing the sum of the optical powers at the differential outputs. DMIs with two differential single-mode outputs are fabricated in a 250 nm SOI platform, and corresponding measurements are shown to explain the principle of operation in detail. A comparison of DMIs with the conventional Mach-Zehnder interferometer using the same technology concludes this work.
      Citation: Biosensors
      PubDate: 2017-09-14
      DOI: 10.3390/bios7030037
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 38: Mediatorless Impedance Studies with Titanium
           Dioxide Conjugated Gold Nanoparticles for Hydrogen Peroxide Detection

    • Authors: Nur Abdul Halim, Yook Lee, Radha Marugan, Uda Hashim
      First page: 38
      Abstract: An impedimetric-based biosensor constructed using gold nanoparticles (AuNP) entrapped within titanium dioxide (TiO2) particles for hydrogen peroxide (H2O2) detection is the main feature of this research. The matrix of the biosensor employed the surface of TiO2, which was previously modified with an amine terminal group using 3-Aminopropyltriethoxysilane (APTS) at a low temperature to create a ready to immobilise surface for the biosensor application. Hemoglobin (Hb), which exhibits peroxidase-like activity, was used as the bioreceptor in the biosensor to detect H2O2 in solution. The analysis was carried out using an alternative impedance method, in which the biosensor exhibited a wide linear range response between 1 × 10−4 M and 1.5 × 10−2 M and a limit of detection (LOD) of 1 × 10−5 M without a redox mediator.
      Citation: Biosensors
      PubDate: 2017-09-18
      DOI: 10.3390/bios7030038
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 39: Substituting Sodium Hydrosulfite with Sodium
           Metabisulfite Improves Long-Term Stability of a Distributable Paper-Based
           Test Kit for Point-of-Care Screening for Sickle Cell Anemia

    • Authors: Kian Torabian, Dalia Lezzar, Nathaniel Piety, Alex George, Sergey Shevkoplyas
      First page: 39
      Abstract: Sickle cell anemia (SCA) is a genetic blood disorder that is particularly lethal in early childhood. Universal newborn screening programs and subsequent early treatment are known to drastically reduce under-five SCA mortality. However, in resource-limited settings, cost and infrastructure constraints limit the effectiveness of laboratory-based SCA screening programs. To address this limitation our laboratory previously developed a low-cost, equipment-free, point-of-care, paper-based SCA test. Here, we improved the stability and performance of the test by replacing sodium hydrosulfite (HS), a key reducing agent in the hemoglobin solubility buffer which is not stable in aqueous solutions, with sodium metabisulfite (MS). The MS formulation of the test was compared to the HS formulation in a laboratory setting by inexperienced users (n = 3), to determine visual limit of detection (LOD), readout time, diagnostic accuracy, intra- and inter-observer agreement, and shelf life. The MS test was found to have a 10% sickle hemoglobin LOD, 21-min readout time, 97.3% sensitivity and 99.5% specificity for SCA, almost perfect intra- and inter-observer agreement, at least 24 weeks of shelf stability at room temperature, and could be packaged into a self-contained, distributable test kits comprised of off-the-shelf disposable components and food-grade reagents with a total cost of only $0.21 (USD).
      Citation: Biosensors
      PubDate: 2017-09-20
      DOI: 10.3390/bios7030039
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 40: Use of Wavelet Transform to Detect
           Compensated and Decompensated Stages in the Congestive Heart Failure

    • Authors: Pratibha Sharma, Kimberly Newman, Carlin Long, A. Gasiewski, Frank Barnes
      First page: 40
      Abstract: This research work is aimed at improving health care, reducing cost, and the occurrence of emergency hospitalization in patients with Congestive Heart Failure (CHF) by analyzing heart and lung sounds to distinguish between the compensated and decompensated states. Compensated state defines stable state of the patient but with lack of retention of fluids in lungs, whereas decompensated state leads to unstable state of the patient with lots of fluid retention in the lungs, where the patient needs medication. Acoustic signals from the heart and the lung were analyzed using wavelet transforms to measure changes in the CHF patient’s status from the decompensated to compensated and vice versa. Measurements were taken on CHF patients diagnosed to be in compensated and decompensated states by using a digital stethoscope and electrocardiogram (ECG) in order to monitor their progress in the management of their disease. Analysis of acoustic signals of the heart due to the opening and closing of heart valves as well as the acoustic signals of the lungs due to respiration and the ECG signals are presented. Fourier, short-time Fourier, and wavelet transforms are evaluated to determine the best method to detect shifts in the status of a CHF patient. The power spectra obtained through the Fourier transform produced results that differentiate the signals from healthy people and CHF patients, while the short-time Fourier transform (STFT) technique did not provide the desired results. The most promising results were obtained by using wavelet analysis. Wavelet transforms provide better resolution, in time, for higher frequencies, and a better resolution, in frequency, for lower frequencies.
      Citation: Biosensors
      PubDate: 2017-09-20
      DOI: 10.3390/bios7030040
      Issue No: Vol. 7, No. 3 (2017)
  • Biosensors, Vol. 7, Pages 15: Detection of 17 β-Estradiol in
           Environmental Samples and for Health Care Using a Single-Use,
           Cost-Effective Biosensor Based on Differential Pulse Voltammetry (DPV)

    • Authors: Yifan Dai, Chung Liu
      First page: 15
      Abstract: Environmental estrogen pollution and estrogen effects on the female reproductive system are well recognized scientifically. Among the estrogens, 17 β-estradiol is a priority in environmental estrogen pollution, and it is also a major contributor to estrogen which regulates the female reproductive system. 17 β-estradiol is carcinogenic and has a tumor promotion effect relating to breast cancer, lung cancer and others. It also affects psychological well-being such as depression, fatigue and others. Thus, a simple method of detecting 17 β-estradiol will be important for both environmental estrogen pollution and health care. This study demonstrates a single-use, cost-effective 17 β-estradiol biosensor system which can be used for both environmental and health care applications. The bio-recognition mechanism is based on the influence of the redox couple, K3Fe(CN)6/K4Fe(CN)6 by the interaction between 17 β-estradiol antigen and its α-receptor (ER-α; α-estrogen antibody). The transduction mechanism is an electrochemical analytical technique, differential pulse voltammetry (DPV). The levels of 17 β-estradiol antigen studied were between 2.25 pg/mL and 2250 pg/mL; Phosphate buffered saline (PBS), tap water from the Cleveland regional water district, and simulated urine were used as the test media covering the potential application areas for 17 β-estradiol detection. An interference study by testosterone, which has a similar chemical structure and molecular weight as those of 17 β-estradiol, was carried out, and this 17 β-estradiol biosensor showed excellent specificity without any interference by similar chemicals.
      PubDate: 2017-03-29
      DOI: 10.3390/bios7020015
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 16: Electrochemical Field-Effect Transistor
           Utilization to Study the Coupling Success Rate of Photosynthetic Protein
           Complexes to Cytochrome c

    • Authors: Arash Takshi, Houman Yaghoubi, Jing Wang, Daniel Jun, J. Beatty
      First page: 16
      Abstract: Due to the high internal quantum efficiency, reaction center (RC) proteins from photosynthetic organisms have been studied in various bio-photoelectrochemical devices for solar energy harvesting. In vivo, RC and cytochrome c (cyt c; a component of the biological electron transport chain) can form a cocomplex via interprotein docking. This mechanism can be used in vitro for efficient electron transfer from an electrode to the RC in a bio-photoelectrochemical device. Hence, the success rate in coupling RCs to cyt c is of great importance for practical applications in the future. In this work, we use an electrochemical transistor to study the binding of the RC to cytochrome. The shift in the transistor threshold voltage was measured in the dark and under illumination to estimate the density of cytochrome and coupled RCs on the gate of the transistor. The results show that ~33% of the cyt cs on the transistor gate were able to effectively couple with RCs. Due to the high sensitivity of the transistor, the approach can be used to make photosensors for detecting low light intensities.
      PubDate: 2017-03-30
      DOI: 10.3390/bios7020016
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 17: Ultrasensitive Label-Free Sensing of IL-6
           Based on PASE Functionalized Carbon Nanotube Micro-Arrays with
           RNA-Aptamers as Molecular Recognition Elements

    • Authors: Farhad Khosravi, Seyed Loeian, Balaji Panchapakesan
      First page: 17
      Abstract: This study demonstrates the rapid and label-free detection of Interleukin-6 (IL-6) using carbon nanotube micro-arrays with aptamer as the molecular recognition element. Single wall carbon nanotubes micro-arrays biosensors were manufactured using photo-lithography, metal deposition, and etching techniques. Nanotube biosensors were functionalized with 1-Pyrenebutanoic Acid Succinimidyl Ester (PASE) conjugated IL-6 aptamers. Real time response of the sensor conductance was monitored with increasing concentration of IL-6 (1 pg/mL to 10 ng/mL), exposure to the sensing surface in buffer solution, and clinically relevant spiked blood samples. Non-specific Bovine Serum Albumin (BSA), PBS samples, and anti-IgG functionalized devices gave similar signatures in the real time conductance versus time experiments with no significant change in sensor signal. Exposure of the aptamer functionalized nanotube surface to IL-6 decreased the conductance with increasing concentration of IL-6. Experiments based on field effect transistor arrays suggested shift in drain current versus gate voltage for 1 pg and 1 ng of IL-6 exposure. Non-specific BSA did not produce any appreciable shift in the Ids versus Vg suggesting specific interactions of IL-6 on PASE conjugated aptamer surface gave rise to the change in electrical signal. Both Z axis and phase image in an Atomic Force Microscope (AFM) suggested unambiguous molecular interaction of the IL-6 on the nanotube-aptamer surface at 1 pg/mL concentration. The concentration of 1 pg falls below the diagnostic gray zone for cancer (2.3 pg-4 ng/mL), which is an indicator of early stage cancer. Thus, nanotube micro-arrays could potentially be developed for creating multiplexed assays involving cancer biomarker proteins and possibly circulating tumor cells all in a single assay using PASE functionalization protocol.
      PubDate: 2017-04-17
      DOI: 10.3390/bios7020017
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 18: Erratum: Irvine, G.W.; Tan, S.N.; Stillman,
           M.J. A Simple Metallothionein-Based Biosensor for Enhanced Detection of
           Arsenic and Mercury. Biosensors 2017, 7, 14

    • Authors: Biosensors Editorial Office
      First page: 18
      Abstract: n/a
      PubDate: 2017-05-05
      DOI: 10.3390/bios7020018
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 19: A Label-Free, Quantitative Fecal Hemoglobin
           Detection Platform for Colorectal Cancer Screening

    • Authors: Gita Soraya, Thanh Nguyen, Chathurika Abeyrathne, Duc Huynh, Jianxiong Chan, Phuong Nguyen, Babak Nasr, Gursharan Chana, Patrick Kwan, Efstratios Skafidas
      First page: 19
      Abstract: The early detection of colorectal cancer is vital for disease management and patient survival. Fecal hemoglobin detection is a widely-adopted method for screening and early diagnosis. Fecal Immunochemical Test (FIT) is favored over the older generation chemical based Fecal Occult Blood Test (FOBT) as it does not require dietary or drug restrictions, and is specific to human blood from the lower digestive tract. To date, no quantitative FIT platforms are available for use in the point-of-care setting. Here, we report proof of principle data of a novel low cost quantitative fecal immunochemical-based biosensor platform that may be further developed into a point-of-care test in low-resource settings. The label-free prototype has a lower limit of detection (LOD) of 10 µg hemoglobin per gram (Hb/g) of feces, comparable to that of conventional laboratory based quantitative FIT diagnostic systems.
      PubDate: 2017-05-05
      DOI: 10.3390/bios7020019
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 20: Raman Spectroscopy of Head and Neck Cancer:
           Separation of Malignant and Healthy Tissue Using Signatures Outside the
           “Fingerprint” Region

    • Authors: Stephen Holler, Elaina Mansley, Christopher Mazzeo, Michael Donovan, Maximiliano Sobrero, Brett Miles
      First page: 20
      Abstract: The ability to rapidly and accurately discriminate between healthy and malignant tissue offers surgeons a tool for in vivo analysis that would potentially reduce operating time, facilitate quicker recovery, and improve patient outcomes. To this end, we investigate discrimination between diseased tissue and adjacent healthy controls from patients with head and neck cancer using near-infrared Raman spectroscopy. Our results indicate previously unreported peaks in the Raman spectra that lie outside the conventional “fingerprint” region (400 cm-1–1800 cm -1) played an important role in our analysis and in discriminating between the tissue classes. Preliminary multivariate statistical analyses of the Raman spectra indicate that discrimination between diseased and healthy tissue is possible based on these peaks.
      PubDate: 2017-05-14
      DOI: 10.3390/bios7020020
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 21: An Enzyme-Induced Novel Biosensor for the
           Sensitive Electrochemical Determination of Isoniazid

    • Authors: Rajasekhar Chokkareddy, Natesh Bhajanthri, Gan Redhi
      First page: 21
      Abstract: In this present work, a glassy carbon electrode (GCE) was modified primarily with multiwalled carbon nanotubes (MWCNTs) and a composite of MWCNTs and titanium oxide nanoparticles (TiO2NPs). The enzyme horseradish peroxidase (HRP) was immobilized to enhance the sensing ability of GCE. The proposed biosensor was used for the sensitive determination of isoniazid (INZ) in various pharmaceutical samples. The electrochemical behaviour of the developed MWCNT-TiO2NPs-HRP-GCE biosensor was studied by using cyclic voltammetry (CV) and differential pulse voltammetric (DPV) techniques. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetry (TGA) and transmission electron microscopy (TEM) techniques were used to characterize the developed sensor. Phosphate buffer solution (PBS) with pH 7 was used as supporting electrolyte in the present investigation. The cyclic voltammetric results revealed that the increment of anodic peak currents for the enzyme-induced sensor was almost 8-fold greater than that of a bare GCE. The DPV technique exhibited good limit of detection and limit of quantification values, viz., 0.0335 μM and 0.1118 μM, respectively. Moreover, the developed sensor showed long-lasting stability and repeatability without any interferents. This strongly indicates that the fabricated sensor shows outstanding electrochemical performance towards INZ, with excellent selectivity and sensitivity. The developed sensor was successfully applied to pharmaceutical samples and gave good percentages of recoveries.
      PubDate: 2017-06-05
      DOI: 10.3390/bios7020021
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 22: A Multi-Wavelength Opto-Electronic Patch
           Sensor to Effectively Detect Physiological Changes against Human Skin

    • Authors: Liangwen Yan, Sijung Hu, Abdullah Alzahrani, Samah Alharbi, Panagiotis Blanos
      First page: 22
      Abstract: Different skin pigments among various ethnic group people have an impact on spectrometric illumination on skin surface. To effectively capture photoplethysmographic (PPG) signals, a multi-wavelength opto-electronic patch sensor (OEPS) together with a schematic architecture of electronics were developed to overcome the drawback of present PPG sensor. To perform a better in vivo physiological measurement against skin pigments, optimal illuminations in OEPS, whose wavelength is compatible with a specific skin type, were optimized to capture a reliable physiological sign of heart rate (HR). A protocol was designed to investigate an impact of five skin types in compliance with Von Luschan’s chromatic scale. Thirty-three healthy male subjects between the ages of 18 and 41 were involved in the protocol implemented by means of the OEPS system. The results show that there is no significant difference (p: 0.09, F = 3.0) in five group tests with the skin types across various activities throughout a series of consistent measurements. The outcome of the present study demonstrates that the OEPS, with its multi-wavelength illumination characteristics, could open a path in multiple applications of different ethnic groups with cost-effective health monitoring.
      PubDate: 2017-06-21
      DOI: 10.3390/bios7020022
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 23: Towards a Uniform Metrological Assessment of
           Grating-Based Optical Fiber Sensors: From Refractometers to Biosensors

    • Authors: Francesco Chiavaioli, Carlos Gouveia, Pedro Jorge, Francesco Baldini
      First page: 23
      Abstract: A metrological assessment of grating-based optical fiber sensors is proposed with the aim of providing an objective evaluation of the performance of this sensor category. Attention was focused on the most common parameters, used to describe the performance of both optical refractometers and biosensors, which encompassed sensitivity, with a distinction between volume or bulk sensitivity and surface sensitivity, resolution, response time, limit of detection, specificity (or selectivity), reusability (or regenerability) and some other parameters of generic interest, such as measurement uncertainty, accuracy, precision, stability, drift, repeatability and reproducibility. Clearly, the concepts discussed here can also be applied to any resonance-based sensor, thus providing the basis for an easier and direct performance comparison of a great number of sensors published in the literature up to now. In addition, common mistakes present in the literature made for the evaluation of sensor performance are highlighted, and lastly a uniform performance assessment is discussed and provided. Finally, some design strategies will be proposed to develop a grating-based optical fiber sensing scheme with improved performance.
      PubDate: 2017-06-21
      DOI: 10.3390/bios7020023
      Issue No: Vol. 7, No. 2 (2017)
  • Biosensors, Vol. 7, Pages 4: Alternating Current-Dielectrophoresis
           Collection and Chaining of Phytoplankton on Chip: Comparison of Individual
           Species and Artificial Communities

    • Authors: Coralie Siebman, Orlin Velev, Vera Slaveykova
      First page: 4
      Abstract: The capability of alternating current (AC) dielectrophoresis (DEP) for on-chip capture and chaining of the three species representative of freshwater phytoplankton was evaluated. The effects of the AC field intensity, frequency and duration on the chaining efficiency and chain lengths of green alga Chlamydomonas reinhardtii, cyanobacterium Synechocystis sp. and diatom Cyclotella meneghiniana were characterized systematically. C. reinhardtii showed an increase of the chaining efficiency from 100 Hz to 500 kHz at all field intensities; C. meneghiniana presented a decrease of chaining efficiency from 100 Hz to 1 kHz followed by a significant increase from 1 kHz to 500 kHz, while Synechocystis sp. exhibited low chaining tendency at all frequencies and all field intensities. The experimentally-determined DEP response and cell alignment of each microorganism were in agreement with their effective polarizability. Mixtures of cells in equal proportion or 10-times excess of Synechocystis sp. showed important differences in terms of chaining efficiency and length of the chains compared with the results obtained when the cells were alone in suspension. While a constant degree of chaining was observed with the mixture of C. reinhardtii and C. meneghiniana, the presence of Synechocystis sp. in each mixture suppressed the formation of chains for the two other phytoplankton species. All of these results prove the potential of DEP to discriminate different phytoplankton species depending on their effective polarizability and to enable their manipulation, such as specific collection or separation in freshwater.
      PubDate: 2017-01-05
      DOI: 10.3390/bios7010004
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 6: Acknowledgement to Reviewers of Biosensors in

    • Authors: Biosensors Editorial Office
      First page: 6
      Abstract: The editors of Biosensors would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...]
      PubDate: 2017-01-10
      DOI: 10.3390/bios7010006
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 7: Surface-Enhanced Raman Scattering-Based
           Immunoassay Technologies for Detection of Disease Biomarkers

    • Authors: Joseph Smolsky, Sukhwinder Kaur, Chihiro Hayashi, Surinder Batra, Alexey Krasnoslobodtsev
      First page: 7
      Abstract: Detection of biomarkers is of vital importance in disease detection, management, and monitoring of therapeutic efficacy. Extensive efforts have been devoted to the development of novel diagnostic methods that detect and quantify biomarkers with higher sensitivity and reliability, contributing to better disease diagnosis and prognosis. When it comes to such devastating diseases as cancer, these novel powerful methods allow for disease staging as well as detection of cancer at very early stages. Over the past decade, there have been some advances in the development of platforms for biomarker detection of diseases. The main focus has recently shifted to the development of simple and reliable diagnostic tests that are inexpensive, accurate, and can follow a patient’s disease progression and therapy response. The individualized approach in biomarker detection has been also emphasized with detection of multiple biomarkers in body fluids such as blood and urine. This review article covers the developments in Surface-Enhanced Raman Scattering (SERS) and related technologies with the primary focus on immunoassays. Limitations and advantages of the SERS-based immunoassay platform are discussed. The article thoroughly describes all components of the SERS immunoassay and highlights the superior capabilities of SERS readout strategy such as high sensitivity and simultaneous detection of a multitude of biomarkers. Finally, it introduces recently developed strategies for in vivo biomarker detection using SERS.
      PubDate: 2017-01-12
      DOI: 10.3390/bios7010007
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 8: Composite Hydrogels with Engineered
           Microdomains for Optical Glucose Sensing at Low Oxygen Conditions

    • Authors: Lindsey Bornhoeft, Aniket Biswas, Michael McShane
      First page: 8
      Abstract: There is a growing need for advanced tools that enable frequent monitoring of biomarkers for precision medicine. In this work, we present a composite hydrogel-based system providing real-time optical bioanalyte monitoring. The responsive material, alginate-in-alginate (AnA), is comprised of an alginate hydrogel with embedded bioactive, nanofilm-coated phosphorescent microdomains; palladium tetracarboxyphenylporphyrin serves as an optical indicator, glucose oxidase as a model enzyme, and layer-by-layer deposited polyelectrolyte multilayers (PEMs) as the diffusion barrier. Glutaraldehyde crosslinking of the nanofilms resulted in a dramatic reduction in glucose diffusion (179%) while oxygen transport was not significantly affected. The responses of the AnA hydrogels to step changes of glucose at both ambient and physiological oxygen levels were evaluated, revealing controlled tuning of sensitivity and dynamic range. Stability, assessed by alternately exposing the responsive AnA hydrogels to extremely high and zero glucose concentrations, resulted in no significant difference in the response over 20 cycles. These AnA hydrogels represent an attractive approach to biosensing based on biocompatible materials that may be used as minimally-invasive, implantable devices capable of optical interrogation. The model glucose-responsive composite material studied in this work will serve as a template that can be translated for sensing additional analytes (e.g., lactate, urea, pyruvate, cholesterol) and can be used for monitoring other chronic conditions.
      PubDate: 2017-01-22
      DOI: 10.3390/bios7010008
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 9: Carbon Nanotubes as an Effective Opportunity
           for Cancer Diagnosis and Treatment

    • Authors: Alessandro Sanginario, Beatrice Miccoli, Danilo Demarchi
      First page: 9
      Abstract: Despite the current progresses of modern medicine, the resistance of malignant tumors to present medical treatments points to the necessity of developing new therapeutic approaches. In recent years, numerous studies have focused their attention on the promising use of nanomaterials, like iron oxide nanowires, zinc oxide or mesoporous silica nanoparticles, for cancer and metastasis treatment with the advantage of operating directly at the bio-molecular scale. Among them, carbon nanotubes emerged as valid candidates not only for drug delivery, but also as a valuable tool in cancer imaging and physical ablation. Nevertheless, deep investigations about carbon nanotubes’ potential bio-compatibility and cytotoxicity limits should be also critically addressed. In the present review, after introducing carbon nanotubes and their promising advantages and drawbacks for fighting cancer, we want to focus on the numerous and different ways in which they can assist to reach this goal. Specifically, we report on how they can be used not only for drug delivery purposes, but also as a powerful ally to develop effective contrast agents for tumors’ medical or photodynamic imaging, to perform direct physical ablation of metastasis, as well as gene therapy.
      PubDate: 2017-02-15
      DOI: 10.3390/bios7010009
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 10: A Single-Use, In Vitro Biosensor for the
           Detection of T-Tau Protein, A Biomarker of Neuro-Degenerative Disorders,
           in PBS and Human Serum Using Differential Pulse Voltammetry (DPV)

    • Authors: Yifan Dai, Alireza Molazemhosseini, Chung Liu
      First page: 10
      Abstract: A single-use, in vitro biosensor for the detection of T-Tau protein in phosphate-buffer saline (PBS) and undiluted human serum was designed, manufactured, and tested. Differential pulse voltammetry (DPV) served as the transduction mechanism. This biosensor consisted of three electrodes: working, counter, and reference electrodes fabricated on a PET sheet. Both working and counter electrodes were thin gold film, 10 nm in thickness. Laser ablation technique was used to define the size and structure of the biosensor. The biosensor was produced using cost-effective roll-to-roll process. Self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA) were employed to covalently immobilize the anti-T-Tau (T-Tau antibody) on the gold working electrode. A carbodiimide conjugation approach using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) and N–hydroxysuccinimide (NHS) cross-linked anti-T-Tau to the carboxylic groups on one end of the MPA. A T-Tau protein ladder with six isoforms was used in this study. The anti-T-Tau concentration used was 500,000 pg/mL. The T-Tau protein concentration ranged from 1000 pg/mL to 100,000 pg/mL. DPV measurements showed excellent responses, with a good calibration curve. Thus, a practical tool for simple detection of T-Tau protein, a biomarker of neuro-degenerative disorders, has been successfully developed. This tool could also be extended to detect other biomarkers for neuro-degenerative disorders, such as P-Tau protein and β-amyloid 42.
      PubDate: 2017-02-19
      DOI: 10.3390/bios7010010
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 11: State-of-the-Art Methods for Skeletal Muscle
           Glycogen Analysis in Athletes—The Need for Novel Non-Invasive Techniques

    • Authors: Jacob Greene, Julien Louis, Olga Korostynska, Alex Mason
      First page: 11
      Abstract: Muscle glycogen levels have a profound impact on an athlete’s sporting performance, thus measurement is vital. Carbohydrate manipulation is a fundamental component in an athlete’s lifestyle and is a critical part of elite performance, since it can provide necessary training adaptations. This paper provides a critical review of the current invasive and non-invasive methods for measuring skeletal muscle glycogen levels. These include the gold standard muscle biopsy, histochemical analysis, magnetic resonance spectroscopy, and musculoskeletal high frequency ultrasound, as well as pursuing future application of electromagnetic sensors in the pursuit of portable non-invasive quantification of muscle glycogen. This paper will be of interest to researchers who wish to understand the current and most appropriate techniques in measuring skeletal muscle glycogen. This will have applications both in the lab and in the field by improving the accuracy of research protocols and following the physiological adaptations to exercise.
      PubDate: 2017-02-23
      DOI: 10.3390/bios7010011
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 12: High Bacterial Agglutination Activity in a
           Single-CRD C-Type Lectin from Spodoptera exigua (Lepidoptera: Noctuidae)

    • Authors: Leila Gasmi, Juan Ferré, Salvador Herrero
      First page: 12
      Abstract: Lectins are carbohydrate-interacting proteins that play a pivotal role in multiple physiological and developmental aspects of all organisms. They can specifically interact with different bacterial and viral pathogens through carbohydrate-recognition domains (CRD). In addition, lectins are also of biotechnological interest because of their potential use as biosensors for capturing and identifying bacterial species. In this work, three C-type lectins from the Lepidoptera Spodoptera exigua were produced as recombinant proteins and their bacterial agglutination properties were characterized. The lowest protein concentration producing bacterial agglutination against a panel of different Gram+ and Gram− as well as their carbohydrate binding specificities was determined for the three lectins. One of these lectins, BLL2, was able to agglutinate cells from a broad range of bacterial species at an extremely low concentration, becoming a very interesting protein to be used as a biosensor or for other biotechnological applications involving bacterial capture.
      PubDate: 2017-03-01
      DOI: 10.3390/bios7010012
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 13: A Urea Potentiometric Biosensor Based on a
           Thiophene Copolymer

    • Authors: Cheng-Yuan Lai, Peter Foot, John Brown, Peter Spearman
      First page: 13
      Abstract: A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid) (P(3HT-co-3TAA)) was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO) glass electrodes. Urease (Urs) was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA)/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min.
      PubDate: 2017-03-03
      DOI: 10.3390/bios7010013
      Issue No: Vol. 7, No. 1 (2017)
  • Biosensors, Vol. 7, Pages 14: A Simple Metallothionein-Based Biosensor for
           Enhanced Detection of Arsenic and Mercury

    • Authors: Gordon Irvine, Swee Tan, Martin Stillman
      First page: 14
      Abstract: Metallothioneins (MTs) are a family of cysteine-rich proteins whose biological roles include the regulation of essential metal ions and protection against the harmful effects of toxic metals. Due to its high affinity for many toxic, soft metals, recombinant human MT isoform 1a was incorporated into an electrochemical-based biosensor for the detection of As3+ and Hg2+. A simple design was chosen to maximize its potential in environmental monitoring and MT was physically adsorbed onto paper discs placed on screen-printed carbon electrodes (SPCEs). This system was tested with concentrations of arsenic and mercury typical of contaminated water sources ranging from 5 to 1000 ppb. The analytical performance of the MT-adsorbed paper discs on SPCEs demonstrated a greater than three-fold signal enhancement and a lower detection limit compared to blank SPCEs, 13 ppb for As3+ and 45 ppb for Hg2+. While not being as low as some of the recommended drinking water limits, the sensitivity of the simple MT-biosensor would be potentially useful in monitoring of areas of concern with a known contamination problem. This paper describes the ability of the metal binding protein metallothionein to enhance the effectiveness of a simple, low-cost electrochemical sensor.
      PubDate: 2017-03-13
      DOI: 10.3390/bios7010014
      Issue No: Vol. 7, No. 1 (2017)
School of Mathematical and Computer Sciences
Heriot-Watt University
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