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Showing 1 - 200 of 2353 Journals sorted alphabetically
3D Research     Hybrid Journal   (Followers: 19, SJR: 0.214, h-index: 10)
4OR: A Quarterly J. of Operations Research     Hybrid Journal   (Followers: 9, SJR: 1.073, h-index: 25)
AAPS J.     Hybrid Journal   (Followers: 20, SJR: 1.192, h-index: 74)
AAPS PharmSciTech     Hybrid Journal   (Followers: 6, SJR: 0.718, h-index: 54)
Abdominal Imaging     Hybrid Journal   (Followers: 14, SJR: 0.723, h-index: 60)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 2, SJR: 0.447, h-index: 12)
Academic Psychiatry     Full-text available via subscription   (Followers: 22, SJR: 0.492, h-index: 32)
Academic Questions     Hybrid Journal   (Followers: 7, SJR: 0.135, h-index: 6)
Accreditation and Quality Assurance: J. for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26, SJR: 0.378, h-index: 30)
Acoustical Physics     Hybrid Journal   (Followers: 11, SJR: 0.355, h-index: 20)
Acoustics Australia     Hybrid Journal  
Acta Analytica     Hybrid Journal   (Followers: 7, SJR: 0.387, h-index: 6)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1, SJR: 0.624, h-index: 34)
Acta Biotheoretica     Hybrid Journal   (Followers: 5, SJR: 0.419, h-index: 25)
Acta Diabetologica     Hybrid Journal   (Followers: 14, SJR: 1.318, h-index: 46)
Acta Endoscopica     Hybrid Journal   (Followers: 1, SJR: 0.113, h-index: 8)
acta ethologica     Hybrid Journal   (Followers: 4, SJR: 0.465, h-index: 23)
Acta Geochimica     Hybrid Journal   (Followers: 4)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1, SJR: 0.294, h-index: 13)
Acta Geotechnica     Hybrid Journal   (Followers: 7, SJR: 1.818, h-index: 22)
Acta Informatica     Hybrid Journal   (Followers: 5, SJR: 0.524, h-index: 32)
Acta Mathematica     Hybrid Journal   (Followers: 11, SJR: 8.021, h-index: 47)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2, SJR: 0.53, h-index: 29)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 5, SJR: 0.406, h-index: 30)
Acta Mathematica Vietnamica     Hybrid Journal   (SJR: 0.451, h-index: 5)
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal   (SJR: 0.22, h-index: 20)
Acta Mechanica     Hybrid Journal   (Followers: 19, SJR: 0.898, h-index: 52)
Acta Mechanica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.426, h-index: 29)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5, SJR: 0.525, h-index: 18)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.524, h-index: 14)
Acta Neurochirurgica     Hybrid Journal   (Followers: 6, SJR: 0.833, h-index: 73)
Acta Neurologica Belgica     Hybrid Journal   (SJR: 0.348, h-index: 27)
Acta Neuropathologica     Hybrid Journal   (Followers: 5, SJR: 6.61, h-index: 117)
Acta Oceanologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 17)
Acta Parasitologica     Hybrid Journal   (Followers: 9, SJR: 0.581, h-index: 28)
Acta Physiologiae Plantarum     Hybrid Journal   (Followers: 2, SJR: 0.551, h-index: 39)
Acta Politica     Hybrid Journal   (Followers: 13, SJR: 0.658, h-index: 20)
Activitas Nervosa Superior     Hybrid Journal  
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5, SJR: 0.103, h-index: 4)
ADHD Attention Deficit and Hyperactivity Disorders     Hybrid Journal   (Followers: 20, SJR: 0.871, h-index: 15)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 15, SJR: 0.795, h-index: 40)
Adsorption     Hybrid Journal   (Followers: 4, SJR: 0.774, h-index: 52)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3, SJR: 0.319, h-index: 15)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 34, SJR: 0.959, h-index: 44)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15, SJR: 1.255, h-index: 44)
Advances in Contraception     Hybrid Journal   (Followers: 3)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 54, SJR: 1.113, h-index: 14)
Advances in Gerontology     Partially Free   (Followers: 9, SJR: 0.141, h-index: 3)
Advances in Health Sciences Education     Hybrid Journal   (Followers: 22, SJR: 1.397, h-index: 42)
Advances in Manufacturing     Hybrid Journal   (Followers: 3, SJR: 0.2, h-index: 4)
Advances in Polymer Science     Hybrid Journal   (Followers: 41, SJR: 0.637, h-index: 89)
Advances in Therapy     Hybrid Journal   (Followers: 5, SJR: 0.79, h-index: 44)
Aegean Review of the Law of the Sea and Maritime Law     Hybrid Journal   (Followers: 7)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2, SJR: 0.882, h-index: 23)
Aerobiologia     Hybrid Journal   (Followers: 1, SJR: 0.511, h-index: 36)
Aesthetic Plastic Surgery     Hybrid Journal   (Followers: 9, SJR: 0.821, h-index: 49)
African Archaeological Review     Hybrid Journal   (Followers: 15, SJR: 0.612, h-index: 24)
Afrika Matematika     Hybrid Journal   (Followers: 1, SJR: 0.248, h-index: 6)
AGE     Hybrid Journal   (Followers: 7, SJR: 1.358, h-index: 33)
Ageing Intl.     Hybrid Journal   (Followers: 7, SJR: 0.337, h-index: 10)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
Aging Clinical and Experimental Research     Hybrid Journal   (Followers: 3, SJR: 0.529, h-index: 55)
Agricultural Research     Hybrid Journal   (Followers: 3)
Agriculture and Human Values     Hybrid Journal   (Followers: 12, SJR: 1.197, h-index: 49)
Agroforestry Systems     Hybrid Journal   (Followers: 20, SJR: 0.64, h-index: 56)
Agronomy for Sustainable Development     Hybrid Journal   (Followers: 10, SJR: 1.732, h-index: 59)
AI & Society     Hybrid Journal   (Followers: 7, SJR: 0.171, h-index: 19)
AIDS and Behavior     Hybrid Journal   (Followers: 13, SJR: 2.006, h-index: 71)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 3, SJR: 0.706, h-index: 19)
Akupunktur & Aurikulomedizin     Full-text available via subscription   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 3, SJR: 0.566, h-index: 18)
Algebra Universalis     Hybrid Journal   (Followers: 2, SJR: 0.388, h-index: 22)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1, SJR: 0.868, h-index: 20)
Algorithmica     Hybrid Journal   (Followers: 7, SJR: 0.898, h-index: 56)
Allergo J.     Full-text available via subscription   (Followers: 1, SJR: 0.183, h-index: 20)
Allergo J. Intl.     Hybrid Journal   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 4, SJR: 0.729, h-index: 20)
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 3, SJR: 1.392, h-index: 32)
AMBIO     Hybrid Journal   (Followers: 15, SJR: 1.094, h-index: 87)
American J. of Cardiovascular Drugs     Hybrid Journal   (Followers: 13, SJR: 0.864, h-index: 39)
American J. of Community Psychology     Hybrid Journal   (Followers: 23, SJR: 1.237, h-index: 83)
American J. of Criminal Justice     Hybrid Journal   (Followers: 6, SJR: 0.634, h-index: 13)
American J. of Cultural Sociology     Hybrid Journal   (Followers: 11, SJR: 0.283, h-index: 3)
American J. of Dance Therapy     Hybrid Journal   (Followers: 4, SJR: 0.175, h-index: 13)
American J. of Potato Research     Hybrid Journal   (Followers: 2, SJR: 0.558, h-index: 35)
American J. of Psychoanalysis     Hybrid Journal   (Followers: 21, SJR: 0.293, h-index: 13)
American Sociologist     Hybrid Journal   (Followers: 12, SJR: 0.18, h-index: 13)
Amino Acids     Hybrid Journal   (Followers: 8, SJR: 1.362, h-index: 83)
AMS Review     Partially Free   (Followers: 4)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 5, SJR: 0.21, h-index: 37)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 3, SJR: 0.665, h-index: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Analysis of Verbal Behavior     Hybrid Journal   (Followers: 5)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 28, SJR: 1.096, h-index: 123)
Anatomical Science Intl.     Hybrid Journal   (Followers: 2, SJR: 0.301, h-index: 26)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3, SJR: 2.212, h-index: 69)
Animal Cognition     Hybrid Journal   (Followers: 16, SJR: 1.122, h-index: 55)
Annales françaises de médecine d'urgence     Hybrid Journal   (Followers: 1, SJR: 0.156, h-index: 4)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3, SJR: 1.377, h-index: 32)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annali dell'Universita di Ferrara     Hybrid Journal   (SJR: 0.504, h-index: 14)
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1, SJR: 1.167, h-index: 26)
Annals of Behavioral Medicine     Hybrid Journal   (Followers: 11, SJR: 2.112, h-index: 98)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18, SJR: 1.182, h-index: 94)
Annals of Combinatorics     Hybrid Journal   (Followers: 3, SJR: 0.849, h-index: 15)
Annals of Data Science     Hybrid Journal   (Followers: 9)
Annals of Dyslexia     Hybrid Journal   (Followers: 9, SJR: 0.857, h-index: 40)
Annals of Finance     Hybrid Journal   (Followers: 28, SJR: 0.686, h-index: 14)
Annals of Forest Science     Hybrid Journal   (Followers: 4, SJR: 0.929, h-index: 57)
Annals of Global Analysis and Geometry     Hybrid Journal   (Followers: 1, SJR: 1.136, h-index: 23)
Annals of Hematology     Hybrid Journal   (Followers: 14, SJR: 1.117, h-index: 62)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6, SJR: 0.593, h-index: 42)
Annals of Microbiology     Hybrid Journal   (Followers: 10, SJR: 0.402, h-index: 26)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 5, SJR: 0.68, h-index: 45)
Annals of Operations Research     Hybrid Journal   (Followers: 8, SJR: 1.186, h-index: 78)
Annals of Ophthalmology     Hybrid Journal   (Followers: 10)
Annals of Regional Science     Hybrid Journal   (Followers: 7, SJR: 0.405, h-index: 42)
Annals of Software Engineering     Hybrid Journal   (Followers: 12)
Annals of Solid and Structural Mechanics     Hybrid Journal   (Followers: 10, SJR: 0.553, h-index: 8)
Annals of Surgical Oncology     Hybrid Journal   (Followers: 13, SJR: 1.902, h-index: 127)
Annals of Telecommunications     Hybrid Journal   (Followers: 7, SJR: 0.315, h-index: 25)
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1, SJR: 0.931, h-index: 31)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5, SJR: 0.992, h-index: 87)
Apidologie     Hybrid Journal   (Followers: 4, SJR: 1.14, h-index: 57)
APOPTOSIS     Hybrid Journal   (Followers: 8, SJR: 1.554, h-index: 87)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2, SJR: 0.354, h-index: 27)
Applications of Mathematics     Hybrid Journal   (Followers: 1, SJR: 0.274, h-index: 20)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44, SJR: 0.575, h-index: 80)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17, SJR: 0.267, h-index: 26)
Applied Cancer Research     Open Access  
Applied Categorical Structures     Hybrid Journal   (Followers: 2, SJR: 0.361, h-index: 21)
Applied Composite Materials     Hybrid Journal   (Followers: 48, SJR: 0.705, h-index: 35)
Applied Entomology and Zoology     Partially Free   (Followers: 2, SJR: 0.554, h-index: 34)
Applied Geomatics     Hybrid Journal   (Followers: 3, SJR: 0.323, h-index: 9)
Applied Geophysics     Hybrid Journal   (Followers: 8, SJR: 0.541, h-index: 13)
Applied Intelligence     Hybrid Journal   (Followers: 12, SJR: 0.777, h-index: 43)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4, SJR: 0.358, h-index: 34)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 4, SJR: 0.955, h-index: 33)
Applied Mathematics - A J. of Chinese Universities     Hybrid Journal   (SJR: 0.275, h-index: 8)
Applied Mathematics and Mechanics     Hybrid Journal   (Followers: 4, SJR: 0.37, h-index: 26)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 62, SJR: 1.262, h-index: 161)
Applied Physics A     Hybrid Journal   (Followers: 7, SJR: 0.535, h-index: 121)
Applied Physics B: Lasers and Optics     Hybrid Journal   (Followers: 23, SJR: 0.983, h-index: 104)
Applied Psychophysiology and Biofeedback     Hybrid Journal   (Followers: 8, SJR: 0.677, h-index: 47)
Applied Research in Quality of Life     Hybrid Journal   (Followers: 10, SJR: 0.288, h-index: 15)
Applied Solar Energy     Hybrid Journal   (Followers: 17, SJR: 0.251, h-index: 6)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4, SJR: 0.351, h-index: 9)
Aquaculture Intl.     Hybrid Journal   (Followers: 22, SJR: 0.613, h-index: 40)
Aquarium Sciences and Conservation     Hybrid Journal   (Followers: 1)
Aquatic Ecology     Hybrid Journal   (Followers: 30, SJR: 0.646, h-index: 44)
Aquatic Geochemistry     Hybrid Journal   (Followers: 4, SJR: 0.764, h-index: 39)
Aquatic Sciences     Hybrid Journal   (Followers: 12, SJR: 1.172, h-index: 53)
Arabian J. for Science and Engineering     Hybrid Journal   (Followers: 5, SJR: 0.345, h-index: 20)
Arabian J. of Geosciences     Hybrid Journal   (Followers: 1, SJR: 0.417, h-index: 16)
Archaeological and Anthropological Sciences     Hybrid Journal   (Followers: 21, SJR: 1.056, h-index: 15)
Archaeologies     Hybrid Journal   (Followers: 12, SJR: 0.397, h-index: 13)
Archiv der Mathematik     Hybrid Journal   (Followers: 1, SJR: 0.597, h-index: 29)
Archival Science     Hybrid Journal   (Followers: 53, SJR: 0.804, h-index: 22)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7, SJR: 0.28, h-index: 15)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 1, SJR: 0.946, h-index: 23)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (SJR: 4.091, h-index: 66)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 4, SJR: 0.865, h-index: 40)
Archives and Museum Informatics     Hybrid Journal   (Followers: 120)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4, SJR: 2.841, h-index: 40)
Archives of Dermatological Research     Hybrid Journal   (Followers: 6, SJR: 0.9, h-index: 65)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 10, SJR: 0.846, h-index: 84)
Archives of Gynecology and Obstetrics     Hybrid Journal   (Followers: 17, SJR: 0.695, h-index: 47)
Archives of Microbiology     Hybrid Journal   (Followers: 8, SJR: 0.702, h-index: 85)
Archives of Orthopaedic and Trauma Surgery     Hybrid Journal   (Followers: 8, SJR: 1.039, h-index: 56)
Archives of Osteoporosis     Hybrid Journal   (Followers: 2, SJR: 1.092, h-index: 13)
Archives of Sexual Behavior     Hybrid Journal   (Followers: 9, SJR: 1.198, h-index: 74)
Archives of Toxicology     Hybrid Journal   (Followers: 17, SJR: 1.595, h-index: 76)
Archives of Virology     Hybrid Journal   (Followers: 5, SJR: 1.086, h-index: 90)
Archives of Women's Mental Health     Hybrid Journal   (Followers: 13, SJR: 1.264, h-index: 50)
Archivio di Ortopedia e Reumatologia     Hybrid Journal  
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2, SJR: 1.2, h-index: 42)
ArgoSpine News & J.     Hybrid Journal   (SJR: 0.102, h-index: 3)
Argumentation     Hybrid Journal   (Followers: 5, SJR: 0.295, h-index: 18)
Arid Ecosystems     Hybrid Journal   (Followers: 3)
Arkiv för Matematik     Hybrid Journal   (Followers: 1, SJR: 0.948, h-index: 22)
Arnold Mathematical J.     Hybrid Journal   (Followers: 1)
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 1, SJR: 0.797, h-index: 17)
Arthroskopie     Hybrid Journal   (Followers: 1, SJR: 0.145, h-index: 8)
Artificial Intelligence and Law     Hybrid Journal   (Followers: 10, SJR: 0.288, h-index: 25)
Artificial Intelligence Review     Hybrid Journal   (Followers: 14, SJR: 0.948, h-index: 48)
Artificial Life and Robotics     Hybrid Journal   (Followers: 8, SJR: 0.231, h-index: 14)
Asia Europe J.     Hybrid Journal   (Followers: 4, SJR: 0.247, h-index: 9)
Asia Pacific Education Review     Hybrid Journal   (Followers: 9, SJR: 0.371, h-index: 17)
Asia Pacific J. of Management     Hybrid Journal   (Followers: 12, SJR: 1.676, h-index: 50)
Asia-Pacific Education Researcher     Hybrid Journal   (Followers: 11, SJR: 0.353, h-index: 13)
Asia-Pacific Financial Markets     Hybrid Journal   (Followers: 2, SJR: 0.19, h-index: 15)
Asia-Pacific J. of Atmospheric Sciences     Hybrid Journal   (Followers: 20, SJR: 1.006, h-index: 14)
Asian Business & Management     Hybrid Journal   (Followers: 7, SJR: 0.41, h-index: 10)
Asian J. of Business Ethics     Hybrid Journal   (Followers: 7)
Asian J. of Criminology     Hybrid Journal   (Followers: 5, SJR: 0.263, h-index: 8)
AStA Advances in Statistical Analysis     Hybrid Journal   (Followers: 2, SJR: 0.681, h-index: 15)
AStA Wirtschafts- und Sozialstatistisches Archiv     Hybrid Journal   (Followers: 5, SJR: 0.195, h-index: 5)
ästhetische dermatologie & kosmetologie     Full-text available via subscription  

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Journal Cover Analytical and Bioanalytical Chemistry
  [SJR: 1.096]   [H-I: 123]   [28 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1618-2650 - ISSN (Online) 1618-2642
   Published by Springer-Verlag Homepage  [2353 journals]
  • Surface tuning laser desorption/ionization mass spectrometry (STLDI-MS)
           for the analysis of small molecules using quantum dots
    • Authors: Hani Nasser Abdelhamid; Zhen-Yu Chen; Hui-Fen Wu
      Pages: 4943 - 4950
      Abstract: Abstract In most applications of quantum dots (QDs) for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS), one side of QDs is supported by a solid substrate (stainless - steel plate), whereas the other side is in contact with the target analytes. Therefore, the surface capping agent of QDs is a key parameter for laser desorption/ionization mass spectrometry (LDI-MS). Cadmium telluride quantum dots (CdTe QDs) modified with different capping agents are synthesized, characterized, and applied for surface tuning laser desorption/ionization mass spectrometry (STLDI-MS). Data shows that CdTe quantum dot modified cysteine (cys@CdTe QDs) has an absorption that matches with the wavelength of the N2 laser (337 nm). The synergistic effect of large surface area and absorption of the laser irradiation of cys@CdTe QDs enhances the LDI-MS process for small - molecule analysis, including α-, β-, and γ-cyclodextrin, gramicidin D, perylene, pyrene, and triphenylphosphine. Cys@CdTe QDs are also applied using Al foils as substrates. Aluminum foil combined with cys@CdTe QDs enhances the ionization efficiency and is cheap compared to traditional matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with a stainless - steel plate.
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0433-4
      Issue No: Vol. 409, No. 21 (2017)
  • A multifunctional fluorescent aptamer probe for highly sensitive and
           selective detection of cadmium(II)
    • Authors: Yu-Feng Zhu; Yong-Sheng Wang; Bin Zhou; Jun-Hui Yu; Li-Lan Peng; Yan-Qin Huang; Xue-Jiao Li; Si-Han Chen; Xian Tang; Xiao-Feng Wang
      Pages: 4951 - 4958
      Abstract: Abstract We report a highly sensitive and selective strategy for Cd(II) assay using a singly labeled multifunctional probe consisting of a Cd(II)-specific aptamer (CAP), which acted as a recognition element for Cd(II) and a signal reporter. The presence of Cd(II) can induce the conformational switching of the CAP, accompanied by a change in fluorescence intensity. Thereby, a fluorescence strategy for Cd(II) assay was established. The proposed method has a detection limit of 2.15 nM, which is much lower than the detection limits reported in related literature. This strategy involves only an aptamer probe, and the use of such a G4-based quencher avoids the dual labeling of the CAP with fluorophore/quencher units. It is obviously more convenient and economical than the other aptamer-based biosensors for Cd(II) detection. The mechanism by which Cd(II) induces the CAP to change from a random coil sequence to a stem-loop structure was studied in a series of control experiments. This strategy would be helpful in the design of a sensitive analytical platform for various target assays in environmental and biomedical fields. Graphical Abstract The presence of Cd2+ leads to the conformational change of CAP from a random coil sequence to a stem-loop structure, resulting in a quenching in the fluorescence
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0436-1
      Issue No: Vol. 409, No. 21 (2017)
  • Determination of mancozeb residue in fruit by derivatization and a
           modified QuEChERS method using ultraperformance liquid
           chromatography–tandem mass spectrometry
    • Authors: Guofeng Xu; Jiyun Nie; Haifei Li; Zhen Yan; Yang Cheng
      Pages: 5057 - 5063
      Abstract: A liquid chromatography–tandem mass spectrometry method with derivatization and a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation was developed for the determination of mancozeb in fruits. The target compound was determined in less than 4.0 min with use of an electrospray ionization source in positive mode. The limits of detection and the limits of quantification ranged from 1.0 to 3.2 μg kg-1 and from 10 to 15 μg kg-1 in fruit respectively. The linearity was excellent for mancozeb (R 2 ≥ 0.9920). Recoveries in five matrices were obtained at three spiking levels (0.02, 0.1, and 1 mg kg-1). For all concentrations, the mean recoveries ranged from 84.0% to 95.9%, with repeatability relative standard deviation (n = 5) of 0.6 − 7.0%. The interday reproducibility relative standard deviation (n = 3) ranged from 1.4% to 5.5%. This method could be used for the routine detection of mancozeb residues in fruit. Graphical abstract The derivation of mancozeb and the detection process of derivative product by UPLC-MS/MS
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0451-2
      Issue No: Vol. 409, No. 21 (2017)
  • A molecularly imprinted polymer synthesized using β-cyclodextrin as the
           monomer for the efficient recognition of forchlorfenuron in fruits
    • Authors: Yang Cheng; Jiyun Nie; Zhixia Li; Zhen Yan; Guofeng Xu; Haifei Li; Dikai Guan
      Pages: 5065 - 5072
      Abstract: In this study, we have successfully synthesized a forchlorfenuron (CPPU)-imprinted polymer in dimethyl sulfoxide by molecular imprinting technique. In the molecular imprinting, β-cyclodextrin was used as the monomer with 1,6-hexamethylene diisocyanate (HMDI) as the cross-linking agent that formed a complex with forchlorfenuron by inclusion interactions. The adsorption equilibrium was attained in approximately 30 min and the maximum binding capacity was 26.79 mg/g, which indicated that the adsorption kinetics was relatively fast. The results of adsorption and selectivity experiments have shown that the imprinted polymer was able to bind forchlorfenuron specifically and reversibly. The specific recognition of the imprinted polymer for forchlorfenuron resulted from the cooperative effects of inclusion interaction and hydrophobic interaction. This imprinted polymer was also used to accurately determine forchlorfenuron residue in real fruit samples. In the standard spiked strawberry sample, the adsorption recoveries for forchlorfenuron were as high as 90.3, 84.5, and 90.8%, respectively. The binding specificity of the imprinted polymer for forchlorfenuron resulted from the imprinting effect. Therefore, as a reusable material possessing high affinity and selectivity, the imprinted polymer is promising in application to detect pesticide residues in fruit samples. In addition, because β-cyclodextrin is water soluble and can include neutral compounds, this molecularly imprinted polymer can be used to recognize pesticides in aqueous solutions. Graphical abstract Schematic demonstration of molecular imprinting and re-binding of forchlorfenuron
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0452-1
      Issue No: Vol. 409, No. 21 (2017)
  • Ratiometric fluorescent pH nanoprobes based on in situ assembling of
           fluorescence resonance energy transfer between fluorescent proteins
    • Authors: Haijun Yu; Chao Chen; Xiaodan Cao; Yueling Liu; Shengmin Zhou; Ping Wang
      Pages: 5073 - 5080
      Abstract: pH-dependent protein adsorption on mesoporous silica nanoparticle (MSN) was examined as a unique means for pH monitoring. Assuming that the degree of protein adsorption determines the distance separating protein molecules, we examined the feasibility of nanoscale pH probes based on fluorescence resonance energy transfer (FRET) between two fluorescent proteins (mTurquoise2 and mNeonGreen, as donor and acceptor, respectively). Since protein adsorption on MSN is pH-sensitive, both fluorescent proteins were modified to make their isoelectric points (pIs) identical, thus achieving comparable adsorption between the proteins and enhancing FRET signals. The adsorption behaviors of such modified fluorescent proteins were examined along with ratiometric FRET signal generation. Results demonstrated that the pH probes could be manipulated to show feasible sensitivity and selectivity for pH changes in hosting solutions, with a good linearity observed in the pH range of 5.5–8.0. In a demonstration test, the pH probes were successfully applied to monitor progress of enzymatic reactions. Such an “in situ-assembling” pH sensor demonstrates a promising strategy in developing nanoscale fluorescent protein probes. Graphical abstract Working principle of the developed pH sensor TNS; and FRET Ratio (I528/I460) as a function of pH under different protein feed ratios (mNeonGreen to mTurquoise2)
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0453-0
      Issue No: Vol. 409, No. 21 (2017)
  • A simple and sensitive surface-enhanced Raman spectroscopic discriminative
           detection of organophosphorous nerve agents
    • Authors: Jianfeng Wu; Yingjie Zhu; Jing Gao; Jia Chen; Jianlin Feng; Lei Guo; Jianwei Xie
      Pages: 5091 - 5099
      Abstract: Organophosphorous nerve agents (NAs) pose a great threat to nations and people because of their acute and extreme toxicities. The rapid detection of NAs has attracted growing interest in the first emergency response field. In this work, we demonstrate a simple and sensitive surface-enhanced Raman spectroscopic (SERS) method for NAs detection, and G- and V-agents discrimination. The results show that VX (V-agents) can be directly detected at a 20 ng mL−1 level with pinhole shell-isolated gold nanoparticles (pinSHINs) as the substrate. Moreover, combined with a specific and prompt alkaline keto-oxime transformation approach in a full aqueous solution, G-agents can be measured as low as 10 ng mL−1 with excellent discrimination from V-agents and other common organophosphorous pesticides within several minutes. The achieved discriminative detection of G-agents and VX could be significant not only for reducing the false positive and negative signals but also for providing an appropriate recommendation on the effective medical rescue. A decontamination outcome occurred alongside, any highly toxic G-agents were converted to a less toxic phosphate, and the generated cyanide was fully and firmly adsorbed onto the surface of pinSHINs substrate, which may be further used for on-site detection of extremely toxic NA prototypes. Graphical abstract ᅟ
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0457-9
      Issue No: Vol. 409, No. 21 (2017)
  • Magnetic nanoparticles—carbon nanotubes hybrid composites for selective
           solid-phase extraction of polycyclic aromatic hydrocarbons and
           determination by ultra-high performance liquid chromatography
    • Authors: Ana I. Corps Ricardo; Francisco J. Guzmán Bernardo; Mohammed Zougagh; Rosa C. Rodríguez Martín-Doimeadios; Ángel Ríos
      Pages: 5125 - 5132
      Abstract: Abstract A rapid and reliable method based on magnetic solid-phase extraction (MSPE) and ultra-high performance liquid chromatography (UHPLC-FLD) analysis was developed and validated for the quantitative determination of seven polycyclic aromatic hydrocarbons (PAHs) in water samples. Hybrid composites made up of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) were tested as adsorbent materials. The main factors influencing the extraction yields were optimized, namely the amount and type of adsorbent in the adsorption, and the solvent, the type of energy and the time in the desorption step. The selected composite was made up of Fe3O4 and multiwalled (MW)-CNTs. The desorption was carried out with sonication probe and tetrahydrofuran (THF); this solvent makes the method directly compatible with the chromatographic mobile phase and it reduces the analysis time. Under the optimized conditions, the LODs and LOQs achieved were in the range of 0.025–0.73 and 0.04–2.4 ng mL−1, respectively. The calibration curves were linear (R 2 ≥ 0.9936) over the concentration ranges from 1 to 500 ng mL−1. The recoveries of PAHs were from 76.4 ± 1.7 up to 106.5 ± 3.5%. The method was applied to synthetic and real (tap, dam, river and mineral) water samples with different characteristics to evaluate the performance under real conditions.
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0459-7
      Issue No: Vol. 409, No. 21 (2017)
  • A multiresidue method for the analysis of 90 pesticides, 16 PAHs, and 22
           PCBs in honey using QuEChERS–SPME
    • Authors: Josephine Al-Alam; Ziad Fajloun; Asma Chbani; Maurice Millet
      Pages: 5157 - 5169
      Abstract: Abstract An optimized analytical method was developed for the simultaneous analysis of 90 pesticides, 16 polycyclic aromatic hydrocarbons, and 22 polychlorinated biphenyls. The method was based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction using acetonitrile followed by a dispersive solid-phase extraction cleanup using primary–secondary amine and octadecyl (C18). The extract obtained was concentrated by evaporation and then reconstituted with acetonitrile to prepare it for chromatographic analysis by liquid chromatography–triple-quadrupole tandem mass spectrometry and gas chromatography–ion-trap tandem mass spectrometry, which was preceded by a preconcentration step using solid-phase microextraction with appropriate fibers. The combination of the two extraction steps ensured efficient extract cleanup. The use of the two analytical instruments allowed the analysis of a large number of pollutants with a high reliability rate. The method developed was validated for linearity, which was studied with use of matrix-matched calibration curves in the concentration range between 10 and 3000 ng g−1. The correlation coefficient (R 2) obtained was higher than 0.98 for most of the target compounds, with a relative standard deviation lower than 20% for repeatability and reproducibility. The limits of detection and quantification were lower than 20 and 60 ng g-1 respectively for the compounds analyzed, and the recoveries were between 60% and 103% for most compounds. Finally, the method was tested for its efficiency on real samples by the analysis of three honey samples in which seven pesticides and nine polycyclic aromatic hydrocarbons were determined. Graphical Abstract ᅟ
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0463-y
      Issue No: Vol. 409, No. 21 (2017)
  • Thiago Regis Longo Cesar da Paixão and Subrayal M. Reddy (Eds.):
           Materials for chemical sensing
    • Authors: Marco Giannetto
      Pages: 4681 - 4682
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0448-x
      Issue No: Vol. 409, No. 20 (2017)
  • Rapid fluorescence detection of pathogenic bacteria using magnetic
           enrichment technique combined with magnetophoretic chromatography
    • Authors: Yulan Che; Yi Xu; Renjie Wang; Li Chen
      Pages: 4709 - 4718
      Abstract: A rapid and sensitive analytical method was developed to detect pathogenic bacteria which combined magnetic enrichment, fluorescence labeling with polyethylene glycol (PEG) magnetophoretic chromatography. As pathogenic bacteria usually exist in complex matrixes at low concentration, an efficient enrichment is essential for diagnosis. In order to capture series types of pathogenic bacteria in samples, amino-modified magnetic nanoparticles (Fe3O4@SiO2-NH2) were prepared for efficient enrichment by the electrostatic interaction with pathogenic bacteria. It was shown that the capture efficiency reached up to 95.4% for Escherichia coli (E. coli). Furthermore, quantitative analysis of the bacteria was achieved by using acridine orange (AO) as a fluorescence probe for the captured E. coli due to its ability of staining series types of bacteria and rapid labeling. In order to remove the free magnetic nanoparticles and redundant fluorescent reagent, the labeled suspension was poured into a PEG separation column and was separated by applying an external magnetic field. The presence of 100 cfu mL−1 E. coli could be detected for semi-quantitative analysis by observing the separation column with the naked eye, and the concentration could be further evaluated by fluorescence detection. All the above processes were finished within 80 min. It was demonstrated that a good linear relationship existed between the fluorescence intensity and the concentration of E. coli ranging from 102 to 106 cfu mL−1, with a detection limit of 100 cfu mL−1 when E. coli acted as target bacteria. The recovery rate of E. coli was 93.6∼102.0% in tap water and cooked meat samples, and the RSD was lower than 7% (n = 6); the result coincided with the conventional plate count method. Graphical abstract ᅟ
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0415-6
      Issue No: Vol. 409, No. 20 (2017)
  • Laboratory and field studies on a new sensor for dissolved N 2 O
    • Authors: Klemens M. Thaler; Reinhard Niessner; Christoph Haisch
      Pages: 4719 - 4727
      Abstract: Nitrous oxide (N2O) is a strong greenhouse gas, whose atmospheric concentration has been continuously increasing for more than 200 years. One major source is wastewater treatment plants (WWTPs), where N2O emissions should either be minimized or pushed to levels where exploitation in biogas combustion engines becomes efficient. Both these strategies require online control of the N2O concentrations in the liquid as well as in the gas phase. For this purpose, we propose a system for membrane extraction of the gas from the liquid phase, which then allows for a subsequent gas-phase analysis, which we perform by photoacoustic spectroscopy. We compare different theoretical calculations of the extraction efficiency, based either on a straightforward mathematical model or on a finite element simulation. The comparison of results with measurements produced on a well-defined model system shows good accordance. Based on the outcome, a field probe was developed and tested on a WWTP, yielding results comparable to the one achieved by GC reference analysis. Graphical abstract Gas extraction from liquids, e.g. from a wastewater treatment plant, for online gas monitoring
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0418-3
      Issue No: Vol. 409, No. 20 (2017)
  • Design of a novel electrochemical biosensor based on intramolecular
           G-quadruplex DNA for selective determination of lead(II) ions
    • Authors: Maryam Ebrahimi; Jahan Bakhsh Raoof; Reza Ojani
      Pages: 4729 - 4739
      Abstract: An electrochemical DNA biosensor based on a G-quadruplex (G4) for the sensitive determination of Pb2+ was reported using a carbon paste electrode (CPE) or a multi-walled carbon nanotube paste electrode (MWCNTPE) as working electrodes, ethyl green (EG) as a new G4 intercalator, and a single-stranded nucleic acid sequence rich in guanine (G) as DNA probe. Electrochemical determination of Pb2+ relied on probe structural changes from single - stranded to the stabilized intramolecular G4 in the presence of Pb2+, which caused a change in the current of the EG reduction peak due to the intercalation of EG into the G4 structure. The change in the reduction peak of EG before and after its intercalation into the stabilized G4 (∆I) had a linear correlation to the concentration of Pb2+ ions. The linear ranges of 4.0 × 10−10–5.0 × 10−9 M and 2 × 10−7–1 × 1−5 M with a detection limit (LOD) of 1.04 × 10−10 M were obtained using CPE, while improved linear ranges of 4.0 × 10−11–1.0 × 10−9 M and 2 × 10−7–1 × 10−5 M with a lower LOD of 2.64 × 10−11 M were achieved using the MWCNTPE biosensor. The biosensors exhibited satisfactory results in terms of selectivity and practical applicability in the analysis of real samples. Graphical abstract The principle of the electrochemical sensing of Pb2+ based on intramolecular G-quadruplex using EG.
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0416-5
      Issue No: Vol. 409, No. 20 (2017)
  • Preparation of polymer brushes grafted graphene oxide by atom transfer
           radical polymerization as a new support for trypsin immobilization and
           efficient proteome digestion
    • Authors: Cong Guo; Xinyuan Zhao; Wanjun Zhang; Haihong Bai; Weijie Qin; Haifeng Song; Xiaohong Qian
      Pages: 4741 - 4749
      Abstract: Highly efficient protein digestion is one of the key issues in the “bottom-up” strategy-based proteomic studies. Compared with the time-consuming solution-based free protease digestion, immobilized protease digestion offers a promising alternative with obviously improved sample processing throughput. In this study, we proposed a new immobilized protease digestion strategy using two kinds of polymer-grafted graphene oxide (GO) conjugated trypsin. The polymer brush grafted GO was prepared using in situ polymer growth on initiator-functionalized GO using surface-initiated atom transfer radical polymerization (SI-ATRP) and characterized by AFM, TEM, TGA, and XPS. The polymer brush grafted GO supports three-dimensional trypsin immobilization, which not only increases the loading amount but also improves accessibility towards protein substrates. Both of the two types of immobilized trypsin provide 700 times shorter digestion time, while maintaining comparable protein/peptide identification scale compared with that of free trypsin digestion. More interestingly, combined application of the two types of immobilized trypsin with different surface-grafted polymers leads to at least 18.3/31.3% enhancement in protein/peptide identification compared with that obtained by digestion using a single type, indicating the potential of this digestion strategy for deeper proteome coverage using limited mass spectrometer machine hour. We expect these advantages may find valuable application in high throughput clinical proteomic studies, which often involve processing of a large number of samples. Graphical abstract Preparation of polymer brushes grafted and trypsin immobilized graphene oxide and its application in proteome digestion and mass spectrometry identification.
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0417-4
      Issue No: Vol. 409, No. 20 (2017)
  • Fluorescence turn-on detection of alkaline phosphatase activity based on
           controlled release of PEI-capped Cu nanoclusters from MnO 2 nanosheets
    • Authors: Yunyi Zhang; Yongxin Li; Cuiyun Zhang; Qingfeng Zhang; Xinan Huang; Meiding Yang; Sohail Anjum Shahzad; Kenneth Kam-Wing Lo; Cong Yu; Shichun Jiang
      Pages: 4771 - 4778
      Abstract: Abstract A fluorescence turn-on assay for alkaline phosphatase (ALP) activity is developed through the controlled release of polyethyleneimine-capped copper nanoclusters (PEI-capped CuNCs) from the MnO2 nanosheets. In an aqueous solution, the positively charged PEI-capped CuNCs could be adsorbed onto the surface of the negatively charged MnO2 nanosheets. Such adsorption through favorable electrostatic interactions could efficiently quench the nanocluster fluorescence emission via resonance energy transfer from the PEI-capped CuNCs to the MnO2 nanosheets. 2-Phospho-l-ascorbic acid (AAP) could be hydrolyzed to l-ascorbic acid (AA) in the presence of ALP. AA could reduce MnO2 into Mn2+ and trigger the disintegration of the MnO2 nanosheets. As a result, the CuNCs were released and the quenched fluorescence was recovered efficiently. The detection strategy is simple, inexpensive, sensitive, selective, with low toxicity, and has better biocompatibility. The newly fabricated biosensor for ALP activity will potentially make it a robust candidate for numerous biological and biomedical applications.
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0420-9
      Issue No: Vol. 409, No. 20 (2017)
  • Further optimization of peptide substrate enhanced assay performance for
           BoNT/A detection by MALDI-TOF mass spectrometry
    • Authors: Dongxia Wang; Jakub Baudys; Kaitlin M. Hoyt; John R. Barr; Suzanne R. Kalb
      Pages: 4779 - 4786
      Abstract: Rapid and sensitive detection of botulinum neurotoxins (BoNTs), which cause botulism, is essential in a public health emergency or bioterrorism event. We have previously developed a mass spectrometry (MS)-based functional method, Endopep-MS assay, for the fast detection and differentiation of all BoNT serotypes by affinity enriching the toxin and detecting the serotype-specific cleavage products of peptide substrates derived from the in vivo targets. To improve the performance of the Endopep-MS assay, we report here the further optimization of the peptide substrate for the detection of serotype A botulinum neurotoxins. An increased substrate cleavage was achieved by extending the original peptide N-terminus with optimized amino acid sequence, increasing the detection sensitivity of the method. In addition, the resistance of the substrate to nonspecific hydrolysis was dramatically improved by selectively substituting amino acids at the scissile bond and various other positions of the extended peptide. Moreover, incorporating the N-terminal hydrophobic residues dramatically improved the relative intensity of the cleavage products in the mass spectra. This allowed easy detection of the cleavage products, further enhancing the performance of the assay. The limit of detection for spiked serum sample was enhanced from 0.5 to 0.1 mouseLD50 and from 0.5 to 0.2 mouseLD50 for spiked stool. Graphical abstract Mass spectra of optimized and old peptide substrates with BoNT/A
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0421-8
      Issue No: Vol. 409, No. 20 (2017)
  • Automated chromatographic laccase-mediator-system activity assay
    • Authors: Nico Anders; Maximilian Schelden; Simon Roth; Antje C. Spiess
      Pages: 4801 - 4809
      Abstract: Abstract To study the interaction of laccases, mediators, and substrates in laccase-mediator systems (LMS), an on-line measurement was developed using high performance anion exchange chromatography equipped with a CarboPac™ PA 100 column coupled to pulsed amperometric detection (HPAEC-PAD). The developed method was optimized for overall chromatographic run time (45 to 120 min) and automated sample drawing. As an example, the Trametes versicolor laccase induced oxidation of 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-dihydroxypropane (adlerol) using 1-hydroxybenzotriazole (HBT) as mediator was measured and analyzed on-line. Since the Au electrode of the PAD detects only hydroxyl group containing substances with a limit of detection being in the milligram/liter range, not all products are measureable. Therefore, this method was applied for the quantification of adlerol, and—based on adlerol conversion—for the quantification of the LMS activity at a specific T. versicolor laccase/HBT ratio. The automated chromatographic activity assay allowed for a defined reaction start of all laccase-mediator-system reactions mixtures, and the LMS reaction progress was automatically monitored for 48 h. The automatization enabled an integrated monitoring overnight and over-weekend and minimized all manual errors such as pipetting of solutions accordingly. The activity of the LMS based on adlerol consumption was determined to 0.47 U/mg protein for a laccase/mediator ratio of 1.75 U laccase/g HBT. In the future, the automated method will allow for a fast screening of combinations of laccases, mediators, and substrates which are efficient for lignin modification. In particular, it allows for a fast and easy quantification of the oxidizing activity of an LMS on a lignin-related substrate which is not covered by typical colorimetric laccase assays. ᅟ
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0423-6
      Issue No: Vol. 409, No. 20 (2017)
  • Size-exclusion chromatography of xylan derivatives—the critical
           evaluation of macromolecular data
    • Authors: Leena Pitkänen; Vladimir Aseyev; Christiane Laine; Päivi Tuomainen; Maija Tenkanen
      Pages: 4811 - 4817
      Abstract: Abstract Hydroxypropyl xylans with varying degrees of substitution were characterized by size-exclusion chromatography. Molar masses of the samples were determined using two approaches: by conventional calibration with molar mass standards and by a multi-detection method that utilizes the combination of static light scattering, viscometry, and differential refractive index detection. The molar mass results obtained by the multi-detection method were accurate, but required the determination of separate refractive index increments for each structurally different sample. The column calibration approach with standard pullulan samples gave biased results due to the differences in hydrodynamic volumes between pullulans and hydroxypropyl xylans with similar molar masses. The degree of hydroxypropylation affected the chain conformation and compactness of the polymer chains. Mark-Houwink parameters and persistence length values suggested that the hydroxypropyl substituents reduced the flexibility of the xylan chain and made the polymer chain more extended.
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0424-5
      Issue No: Vol. 409, No. 20 (2017)
  • Differential mobility spectrometry tandem mass spectrometry with multiple
           ion monitoring for the bioanalysis of liraglutide
    • Authors: Xiangjun Meng; Haitong Xu; Zhi Zhang; John Paul Fawcett; Junru Li; Yan Yang; Jingkai Gu
      Pages: 4885 - 4891
      Abstract: Liraglutide is a glucagon-like peptide-1 analog for the treatment of type 2 diabetes. Major interference in plasma of human and animals and low fragment signal in tandem mass spectrometry are the main difficulties encountered in the bioanalysis of liraglutide. In this study, by combining differential mobility spectrometry (DMS) with multiple ion monitoring detection (MIM), a liquid chromatography differential mobility spectrometry tandem mass spectrometry with multiple ion monitoring detection (LC-DMS-MIM) method was developed for the quantitation of liraglutide in dog plasma. Mixed anion-exchange solid-phase extraction was used for sample preparation. The parameters of DMS were meticulously optimized to increase the signal-to-noise ratio of the analyte. The assay was linear in the range 1–100 ng/mL with good accuracy and precision. The lower limit of quantitation (LLOQ, the lowest standard on the calibration curve) of this method was 1 ng/mL. The research reveals that DMS is an effective tool for the elimination of interference in bioanalysis and that LC-DMS-MIM has better specificity and higher signal-to-noise ratio than classical liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the bioanalysis of liraglutide. Graphical abstract Process for the bioanalysis of liraglutide by liquid chromatography differential mobility spectrometry tandem mass spectrometry with multiple ion monitoring detection
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0431-6
      Issue No: Vol. 409, No. 20 (2017)
  • Surface-enhanced Raman scattering (SERS) imaging-guided real-time
           photothermal ablation of target cancer cells using
           polydopamine-encapsulated gold nanorods as multifunctional agents
    • Authors: Changlong Sun; Mingxia Gao; Xiangmin Zhang
      Pages: 4915 - 4926
      Abstract: In this study, we developed a novel “see-and-treat” theranostic system named “surface-enhanced Raman scattering (SERS) imaging-guided real-time photothermal therapy” for accurate cancer detection and real-time cancer cell ablation using the same Raman laser. Facilely synthesized polydopamine-encapsulated gold nanorods (AuNRs), which possess excellent biocompatibility and enhanced stability, were used as multifunctional agents. Under near-infrared (NIR) laser irradiation, polydopamine-encapsulated AuNRs show strong SERS effect and high photothermal conversion efficiency simultaneously. After immobilization of antibodies (anti-EpCAM), polydopamine-encapsulated gold nanorods show high specificity to target cancer cells. Tumor margins could be distinguished facilely by a quick SERS imaging process, which was confirmed by H&E staining results. By focusing the exciting light on detected cancer cells for a prolonged time, cancer cells could be ablated immediately without the need of other procedure. This “see-and-treat” theranostic strategy combining SERS imaging and real-time photothermal therapy using the same Raman laser is proposed for the first time. Experimental results confirmed the feasibility of our “SERS imaging-guided real-time photothermal therapy system.” This novel theranostic strategy can significantly improve the efficiency of cancer therapy in clinical application, allowing the effective ablation of cancer cells with no effects on surrounding healthy tissues. Graphical abstract ᅟ
      PubDate: 2017-08-01
      DOI: 10.1007/s00216-017-0435-2
      Issue No: Vol. 409, No. 20 (2017)
  • A sensitive colorimetric assay system for nucleic acid detection based on
           isothermal signal amplification technology
    • Authors: Bo Hu; Jing Guo; Ying Xu; Hua Wei; Guojie Zhao; Yifu Guan
      Abstract: Rapid and accurate detection of microRNAs in biological systems is of great importance. Here, we report the development of a visual colorimetric assay which possesses the high amplification capabilities and high selectivity of the rolling circle amplification (RCA) method and the simplicity and convenience of gold nanoparticles used as a signal indicator. The designed padlock probe recognizes the target miRNA and is circularized, and then acts as the template to extend the target miRNA into a long single-stranded nucleotide chain of many tandem repeats of nucleotide sequences. Next, the RCA product is hybridized with oligonucleotides tagged onto gold nanoparticles. This interaction leads to the aggregation of gold nanoparticles, and the color of the system changes from wine red to dark blue according to the abundance of miRNA. A linear correlation between fluorescence and target oligonucleotide content was obtained in the range 0.3–300 pM, along with a detection limit of 0.13 pM (n = 7) and a RSD of 3.9% (30 pM, n = 9). The present approach provides a simple, rapid, and accurate visual colorimetric assay that allows sensitive biodetection and bioanalysis of DNA and RNA nucleotides of interest in biologically important samples. Graphical abstract The colorimetric assay system for analyzing target oligonucleotides
      PubDate: 2017-07-08
      DOI: 10.1007/s00216-017-0425-4
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