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  Subjects -> CHEMISTRY (Total: 892 journals)
    - ANALYTICAL CHEMISTRY (55 journals)
    - CHEMISTRY (626 journals)
    - CRYSTALLOGRAPHY (21 journals)
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    - INORGANIC CHEMISTRY (43 journals)
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    - PHYSICAL CHEMISTRY (71 journals)

CHEMISTRY (626 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 735 Journals sorted alphabetically
2D Materials     Hybrid Journal   (Followers: 14)
Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 27)
ACS Catalysis     Hybrid Journal   (Followers: 44)
ACS Chemical Neuroscience     Hybrid Journal   (Followers: 22)
ACS Combinatorial Science     Hybrid Journal   (Followers: 23)
ACS Macro Letters     Hybrid Journal   (Followers: 26)
ACS Medicinal Chemistry Letters     Hybrid Journal   (Followers: 42)
ACS Nano     Hybrid Journal   (Followers: 306)
ACS Photonics     Hybrid Journal   (Followers: 14)
ACS Symposium Series     Full-text available via subscription  
ACS Synthetic Biology     Hybrid Journal   (Followers: 24)
Acta Chemica Iasi     Open Access   (Followers: 5)
Acta Chimica Slovaca     Open Access   (Followers: 2)
Acta Chimica Slovenica     Open Access   (Followers: 1)
Acta Chromatographica     Full-text available via subscription   (Followers: 8)
Acta Facultatis Medicae Naissensis     Open Access  
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Scientifica Naturalis     Open Access   (Followers: 3)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Adsorption Science & Technology     Open Access   (Followers: 6)
Advanced Functional Materials     Hybrid Journal   (Followers: 60)
Advanced Science Focus     Free   (Followers: 5)
Advances in Chemical Engineering and Science     Open Access   (Followers: 73)
Advances in Chemical Science     Open Access   (Followers: 18)
Advances in Chemistry     Open Access   (Followers: 23)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 19)
Advances in Drug Research     Full-text available via subscription   (Followers: 25)
Advances in Environmental Chemistry     Open Access   (Followers: 7)
Advances in Enzyme Research     Open Access   (Followers: 10)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 12)
Advances in Materials Physics and Chemistry     Open Access   (Followers: 26)
Advances in Nanoparticles     Open Access   (Followers: 15)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 17)
Advances in Polymer Science     Hybrid Journal   (Followers: 45)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
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: 8)
Agrokémia és Talajtan     Full-text available via subscription   (Followers: 2)
Al-Kimia : Jurnal Penelitian Sains Kimia     Open Access  
Alchemy : Journal of Chemistry     Open Access   (Followers: 3)
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: 69)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 22)
American Journal of Chemistry     Open Access   (Followers: 32)
American Journal of Plant Physiology     Open Access   (Followers: 11)
American Mineralogist     Hybrid Journal   (Followers: 16)
Analyst     Full-text available via subscription   (Followers: 38)
Angewandte Chemie     Hybrid Journal   (Followers: 177)
Angewandte Chemie International Edition     Hybrid Journal   (Followers: 257)
Annales UMCS, Chemia     Open Access   (Followers: 1)
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     Open Access   (Followers: 2)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 9)
Applied Spectroscopy     Full-text available via subscription   (Followers: 24)
Applied Surface Science     Hybrid Journal   (Followers: 32)
Arabian Journal of Chemistry     Open Access   (Followers: 6)
ARKIVOC     Open Access   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 3)
Asian Journal of Chemistry and Pharmaceutical Sciences     Open Access  
Atomization and Sprays     Full-text available via subscription   (Followers: 4)
Australian Journal of Chemistry     Hybrid Journal   (Followers: 7)
Autophagy     Hybrid Journal   (Followers: 3)
Avances en Quimica     Open Access  
Biochemical Pharmacology     Hybrid Journal   (Followers: 11)
Biochemistry     Hybrid Journal   (Followers: 377)
Biochemistry Insights     Open Access   (Followers: 6)
Biochemistry Research International     Open Access   (Followers: 6)
BioChip Journal     Hybrid Journal  
Bioinorganic Chemistry and Applications     Open Access   (Followers: 11)
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: 2)
Biomacromolecules     Hybrid Journal   (Followers: 22)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Biomedical Chromatography     Hybrid Journal   (Followers: 6)
Biomolecular NMR Assignments     Hybrid Journal   (Followers: 3)
BioNanoScience     Partially Free   (Followers: 5)
Bioorganic & Medicinal Chemistry     Hybrid Journal   (Followers: 139)
Bioorganic & Medicinal Chemistry Letters     Hybrid Journal   (Followers: 87)
Bioorganic Chemistry     Hybrid Journal   (Followers: 10)
Biopolymers     Hybrid Journal   (Followers: 18)
Biosensors     Open Access   (Followers: 2)
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
Bitácora Digital     Open Access  
Boletin de la Sociedad Chilena de Quimica     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
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: 11)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
Carbohydrate Research     Hybrid Journal   (Followers: 26)
Carbon     Hybrid Journal   (Followers: 70)
Catalysis for Sustainable Energy     Open Access   (Followers: 8)
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: 11)
Cellulose     Hybrid Journal   (Followers: 9)
Cereal Chemistry     Full-text available via subscription   (Followers: 5)
ChemBioEng Reviews     Full-text available via subscription   (Followers: 1)
ChemCatChem     Hybrid Journal   (Followers: 8)
Chemical and Engineering News     Free   (Followers: 22)
Chemical Bulletin of Kazakh National University     Open Access  
Chemical Communications     Full-text available via subscription   (Followers: 75)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 27)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemical Reviews     Hybrid Journal   (Followers: 207)
Chemical Science     Open Access   (Followers: 27)
Chemical Technology     Open Access   (Followers: 32)
Chemical Vapor Deposition     Hybrid Journal   (Followers: 5)
Chemie in Unserer Zeit     Hybrid Journal   (Followers: 57)
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: 33)
Chemistry & Industry     Hybrid Journal   (Followers: 8)
Chemistry - A European Journal     Hybrid Journal   (Followers: 166)
Chemistry - An Asian Journal     Hybrid Journal   (Followers: 16)
Chemistry and Materials Research     Open Access   (Followers: 21)
Chemistry Central Journal     Open Access   (Followers: 4)
Chemistry Education Research and Practice     Free   (Followers: 5)
Chemistry in Education     Open Access   (Followers: 9)
Chemistry International     Open Access   (Followers: 3)
Chemistry Letters     Full-text available via subscription   (Followers: 45)
Chemistry of Materials     Hybrid Journal   (Followers: 267)
Chemistry of Natural Compounds     Hybrid Journal   (Followers: 9)
Chemistry World     Full-text available via subscription   (Followers: 20)
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: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 15)
Chemosensors     Open Access  
ChemPhysChem     Hybrid Journal   (Followers: 12)
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: 23)
Chromatography     Open Access   (Followers: 2)
Chromatography Research International     Open Access   (Followers: 6)
Cogent Chemistry     Open Access   (Followers: 2)
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: 4)
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)
Communications Chemistry     Open Access  
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: 12)
Computational Chemistry     Open Access   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 10)
Coordination Chemistry Reviews     Full-text available via subscription   (Followers: 4)
Copernican Letters     Open Access   (Followers: 1)
Corrosion Series     Full-text available via subscription   (Followers: 7)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 8)
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   (Followers: 1)
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: 9)
Current Science     Open Access   (Followers: 73)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Dalton Transactions     Full-text available via subscription   (Followers: 23)
Detection     Open Access   (Followers: 4)
Developments in Geochemistry     Full-text available via subscription   (Followers: 2)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)

        1 2 3 4 | Last

Journal Cover
Acta Chimica Sinica
Number of Followers: 2  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0567-7351
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  • Synthesis and Study of Hypoxia-responsive Micelles Based on Hyaluronic
           Acid
    • Authors: Zhang Bei; Chang Baisong, Sun Taolei
      Abstract: Hypoxia is a hallmark of tumor. Based on this feature, a hypoxia-responsive drug delivery system combined with tumor-targeting was developed. HA-NI conjugates were prepared by grafting the carboxyl group of hyaluronic acid (HA) with an amine group of nitroimidazole (NI) derivative in the presence of EDC and NHS. The structure of HA-NI conjugates was confirmed by FT-IR and 1H NMR, the degree of substitution (DS) of NI derivative was also calculated based on 1H NMR. Amphiphilic HA-NI conjugates could self-assemble into micelles by ultrasonic method. The size and morphology of micelles were characterized by DLS, AFM and TEM, the stability of micelles was also investigated by DLS. It was found the size of micelles was in the range of 80 nm-220 nm while the DS decreased from 6.5% to 3.6%. Doxorubicin (DOX) was encapsulated in micelles, and DOX-loaded micelles had smaller sizes compared with blank micelles. Drug-loading (DL) and entrapment efficiency (EE) were obtained by UV-Vis analysis and increased with the increasing DS. Under hypoxic condition, micelles became bigger and size distribution of micelles became wider, it was clear to observe the destruction of micelles by AFM and TEM. UV spectrum revealed the characteristic peak belonging to NI at 325 nm disappeared and Zeta potential increased from -30.6 ±0.4 mV to -24.9 ±0.5 mV 6 h later. In vitro drug release studies demonstrated that DOX was released from HA-NI micelles in a hypoxia-dependent manner:micelles were sufficiently stable at normoxic condition while accomplished a rapid drug release under hypoxic condition.
      PubDate: 2017-11-10 00:00:00.0
       
  • Single-Molecule Analysis of Colorectal Cancer-associated MicroRNAs via a
           Biological Nanopore
    • Authors: Hu Zhengli; Du Jihui, Ying Yilun, Peng Yueyi, Cao Chan, Yi-Tao Long
      Abstract: MicroRNAs (miRNAs), 18-22 nucleotides in length, are a class of single-strand noncoding short RNAs and have been used as biomarkers for diagnosis and prognosis of cancers. Herein, an α-hemolysin (α-HL) nanopore was adapted for the colorectal cancer-associated miRNAs analysis, with the merits of high-throughput, ultra-sensitivity and no requirements of amplification/labelling. DNA probes, consisting of a signal tag in each end and a response element in the middle section, were designed. The response element could be well-matched with miRNA and utilized for specific recognition of the target miRNA, while the signal tag increased the capture rate of the miRNA · probe complex. Due to the poor stacking of thymine residues, poly(dT)n need to overcome a high entropic barrier when traversing through the α-HL nanopore confined space, resulting in distinct double-level blocked events, which contributes to the visualized differences in signal shape and prolonged duration. Thus, poly(dT)n was selected as the signal tag of probe. Added in the cis side of α-HL, miRNA · probe was forced to traverse across the nanopore confined space under the potential of 140 mV through a pair of Ag/AgCl electrodes (cis grounded). Typical three-stage blocked event was observed, reflecting the translocation process:capture and dissociation of miRNA · probe, translocation of probe, temporarily residence and translocation of miRNA. Stage 1(S1) represented the process from capture of miRNA· probe complex to translocation of the entire probe. The typical blocked events of miRNA 92· probe 92 showed a two-level S1, where Level 1(L1) with a current blockage of 0.57±0.01 was generated mainly by translocation of the poly(dT)40 signal tag. As the duration is associated with DNA length, probe 21 with smaller poly(dT)20 signal tag was designed to detect miRNA 21, resulting in a shorter L1 of miRNA 21· probe 21 whose duration (tD-L1) was 1/3 of that for miRNA 92· probe 92. As the signal shapes vary with DNA sequences, probe 16 with signal tag of poly(dC)40 was used to sense miRNA 16, with miRNA 16· probe 16 producing a different single-level S1 with miRNA 92· probe 92 and miRNA 21· probe 21. The statistical results demonstrated that the three kinds of miRNA · probe produced different durations for S1(tD-S1), possibly indicating the differences in probe-α-HL interaction. Therefore, miRNA 92, miRNA 21 and miRNA 16 could be well identified by tD-L1(signal shape) and tD-S1(duration). Moreover, the serum sample have been tested. Hence, α-HL nanopore can be applied to build ultrasensitive single molecule biosensor for miRNA.
      PubDate: 2017-11-07 00:00:00.0
       
  • FRET-based Ratiometric MicroRNA Detection with G-quadruplex-stabilized
           Silver Nanoclusters
    • Authors: Ruoyun Lin; Yang Chen, Guangyu Tao, Xiaojing Pei, Feng Liu, Na Li
      Abstract: Fluorescent DNA-stabilized Ag nanoclusters (DNA-Ag NCs), a class of excellent luminescence probes with excellent optical properties, have been applied in assorted sensing and imaging fields. To date, most of the quantifications were based on the direct signal change of DNA-Ag NCs caused by target recognition, which inevitably jeopardizes the reproducibility and robustness of methods when experimental settings or detecting conditions are changed. In this work, using the highly fluorescent G-quadruplex-stabilized Ag NCs (GQ-Ag NCs) and Cy5 as the donor-acceptor pair, we for the first time developed a FRET based ratiometric method for miRNA detection. A rationally optimized hairpin recognition structure was attached to the G-quadruplex template of the Ag nanocluster. The introduction of target sequence opened the hairpin, led to the approximation of the donor nanocluster and the acceptor Cy5, enabled the energy transfer between the FRET pair, and thus generated the optical signal change. The Cy5 tag sequence was designed to be universal, simplifying the experimental design and reduced the cost in applications. The optical signal for quantitation was determined by the signal difference between the Ag nanolcuster and the Cy5 fluorophore, with the fluorescence intensity of Cy5 used as internal reference in order to prevent signal variation. MicroRNAs (miRNA) are short RNA molecules that have emerged as a kind of key post-translational regulators of gene expression in eukaryotic organisms. In this study, microRNA let-7a was chosen as the model target of our FRET-based ratiometric detection for demonstration. The linear range and the detection limit of the method on let-7a was 12-300 nM and 6.9 nM, respectively. The proposed method presented reasonable selectivity amongst the members of the same let-7 family. The remarkable recovery in total RNA extracted from HepG2 cell lines demonstrated the potential in clinical applications. The highlights of our work extended the application of DNA-templated Ag NCs and facilitated more understanding of DNA-Ag NCs as the energy donor in FRET design.
      PubDate: 2017-11-07 00:00:00.0
       
  • (NH4)2MoS4-guided self-assembly of CdTe QDs and control over their optical
           properties and cell imaging
    • Authors: Sun Quanhong; Li Zhi, Ma Nan
      Abstract: Conventionally, red shift of QD photolumine directly scence (PL) could be achieved by growing QDs to larger sizes using hydrothermal method, which is usually a very slow process. We synthesized green fluorescent CdTe quantum dots with GSH as the ligand and proved the successful synthesis of (NH4)2MoS4 by UV-Vis, X-Ray Diffraction, Raman spectroscopy. In the process of research, we found that (NH4)2MoS4 can change the wavelength of CdTe quantum dots under the condition of heating or at room temperature. Redshift of emission wavelength can change with the different ratio between (NH4)2MoS4 and CdTe QDs.In this study, we report a rapid and convenient method to achieve red-shift of CdTe QD PL via (NH4)2MoS4-guided QD self-assembly. We show that the emission wavelength of CdTe QDs underwent a red-shift of more than 100 nm for 15 min at 100 ℃ in the presence of (NH4)2MoS4. At the same time, we conduct a experiment, which have no red-shift in the absence of (NH4)2MoS4 for 15 min at 100 ℃. This illustrates that the (NH4)2MoS4 plays an important role in CdTe QDs self-assembly The red-shift of QD PL was also observed at room temperature but relatively slower. The formation of QD assembly was confirmed by gel electrophoresis, transmission electron microscopy, and X-ray photoelectron spectroscopy. The result of gel electrophoresis and transmission electron microscopy directly shows the self-assemble of CdTe QDs and the change of size and shape. Self-assembly entity was proved to contain Mo and Cd by the X-ray photoelectron spectroscopy, which confirmed the connection between (NH4)2MoS4 and CdTe QDs. A control experiment was conducted by replacing (NH4)2MoS4 with Na2S for QD assembly, in that case no apparent change of emission wavelength was observed. These results reveal that MoS42- within (NH4)2MoS4 is crucial for self-assembly of CdTe QDs. Accordingly, we propose a reasonable model of (NH4)2MoS4-guided CdTe QD self-assembly. In this model, we consider the connection between a (NH4)2MoS4 and two CdTe QDs in ideal condition. With the increasing ratio of (NH4)2MoS4, much more connection between (NH4)2MoS4 and CdTe will be obtained. Assembling entity morphology is differences because of the different crosslinking way. The resulting QD assembly was further applied to cell imaging experiments, demonstrating their potentials in this field.
      PubDate: 2017-11-06 00:00:00.0
       
  • A New Four-Dimensional Potential Energy Surface and Predicted Infrared
           Spectra for the Kr-CS2 Complex
    • Authors: Hong Qi; Qin Miao, Zhu Hua
      Abstract: We present a four-dimensional (4D) ab initio potential energy surface (PES) for the Kr-CS2 complex involving the Q1 and Q3 normal modes for the v1 symmetric stretching vibration and v3 antisymmetric stretching vibration of CS2. The potential energies is calculated using the supermolecular approach at the coupled-cluster singles and doubles with noniterative inclusion of connected triples [CCSD(T)]-F12 level with a large basis set including midpoint bond functions. Two vibrationally averaged potentials with CS2 at the vibrational ground and v1+v3 excited states are generated from the four-dimensional potential. Each potential contains a T-shaped global minimum and two equivalent linear local minima. The rovibrational energy levels and bound states are calculated employing radial discrete variable representation (DVR)/angular finite basis representation (FBR) and the Lanczos algorithm. The spectroscopic parameters for the ground and the v1+v3 excited states of Kr-CS2 are predicted. In addition, the predicted band origin shift is -1.2357cm-1 for Kr-CS2.
      PubDate: 2017-11-06 00:00:00.0
       
  • Recent Progress on Circularly Polarized Luminescence of Chiral Organic
           Small Molecules
    • Authors: Li Meng; Lin Wei-Bin, Fang Lei, Chen Chuan-Feng
      Abstract: Circularly polarized luminescence (CPL) not only can reflect the excited state structure information of chiral system, but also has wide potential applications in 3D display, communication of spin information, information storage and processing, CPL laser and biological probe. Consequently, more and more attention and interests have been attracted into this field, which turns to be one of the most hot topics in organic luminescence materials in recent years. In this review, recent progress on the chiral organic small molecules with CPL properties is summarized. First, CPL concept and earlier studies of CPL and organic small molecules with CPL properties are briefly introduced. Then, chiral organic small molecules with CPL properties are classified into four types of central chirality, axial chirality, planar chirality, and helical chirality, and their progresses in recent years are systematically described, respectively. Among the small molecular systems with different types of chirality, those ones based on the biaryl skeleton and helicene derivatives show excellent CPL properties, and they could also be controlled or switched by anions, protons and others. Moreover, it should be paid attention to the applications of aggregation induced effect (AIE) and supramolecular chemistry for the chiral organic small molecules to obtain better CPL property. Finally, a conclusion and perspective on CPL materials based on chiral small molecules is provided.
      PubDate: 2017-11-01 00:00:00.0
       
  • Preparation of Ni/C Core-shell Nanoparticles through MOF Pyrolysis for
           Phenylacetylene Hydrogenation Reaction
    • Authors: Xiaoling Guo; Xiao Chen, Dangsheng Su, Changhai Liang
      Abstract: A series of Ni/C core-shell nano catalysts with abundant mesoporous and uniform size were prepared by Ni-MOF-74 pyrolysis. The Ni-MOF-74 was synthesized via hydrothermal method with nickel acetate and 2,5-dihydroxyterephthalic acid (DHTA) as raw materials. The pyrolysis process was carried out in a tube furnace under Argon (Ar) atmosphere with a heating rate of 2℃/min. Completed pyrolytic product Ni/C can be obtained by extending the pyrolysis time (6 h) at 400℃ or increasing the pyrolysis temperature (≥ 500℃) based on the TG result. Moreover, the particle size of Ni/C varied with pyrolysis temperature from 3 nm (500℃) to 17 nm (800℃). The TEM images and Ar ion sputtering XPS indicated a core-shell structure of the pyrolysis product. Nickel species can be stable in the form of nickel (Ni0) due to the electronic properties regulating and confinement effect of the carbon shell. Moreover, the carbon shell greatly weaken the interaction between particles, which is favorable for the dispersion of the catalyst in the reaction system. H2-TPR results show that the interaction between nickel and amorphous carbon increases with the pyrolysis temperature, which is unfavorable to the interaction between Ni species and the reactant. The phenylacetylene (PA) hydrogenation reaction was carried out with 0.2 g catalyst, 10 mL of 1 M ethanolic phenylacetylene solution and 1.0 MPa H2 in a 50 mL high-pressure autoclave under 50℃. Ni/C exhibits excellent catalytic activity and recyclability in phenylacetylene (PA) hydrogenation. In addition, we compare the activity of Ni/C with several reported catalyst system and find their activity increases in the order of Ni, NiSix, supported Ni2Si, Ni/C, Pd and Pt. With an activity of up to 0.833 mmol·min-1·gcat.-1 at 50℃ (Ni/C-400-6, Ni/C-500-2), Ni/C is the most promising transition metal catalyst that can be comparable with noble metal.
      PubDate: 2017-10-24 00:00:00.0
       
  • Research review on the applications of immobilized Ionic Liquids
           functional materials
    • Authors: Yinhang Wang; Wei Li, Sha Luo, Shouxin Liu, Chunhui Ma, Jian Li
      Abstract: As the biomass energy and green chemistry processes have gained more and more attention form researchers, ionic liquids as a novel green solvent which were widely concerned by research teams since the nineteen nineties, because of many excellent properties of chemical stability, low viscosity, high conductivity and so on. It is verging to perfect and plentiful in many research areas, especially in the fields of catalytic reaction, photoelectron chemistry, materials chemistry and biomass pretreatment. However, some disadvantages such as large consumption, high cost, hard to separate, and complexity in purification process were appeared. Thus, in recent years, plenty of scholars tried to immobilize ILs on inorganic porous materials or organic polymer materials by the method physical adsorption or chemical grafting. In this way, the characteristics of ILs were transferred to the polyphase solid catalysts, and it can be applied to the continuous and closed fixed-bed reactions. In this review, the birth and the development of immobilized ionic liquid technology were summarized in detail,and the current applications of immobilized ionic liquid were illustrated with a multi-angle. The immobilized ionic liquid as catalysts were used in chemical catalytic field depending on the chemical structure of ionic liquid; While the immobilized ionic liquid as a functional materials were used in adsorption separation field depending on the surface characteristic of solid carrier.
      PubDate: 2017-10-24 00:00:00.0
       
  • Superhalogen Substitutions in Cubic Halide Perovskite Materials for Solar
           Cells:A First-principles Investigation
    • Authors: Wu Miao Miao; Liu Shiqiang, Chen Hao, Wei Xuehu, Li Mingyang, Yang Zhibin, Ma Xiangdong
      Abstract: Halide perovskite (ABC3) solar cell has received a lot of attentions due to its excellent photoelectronic properties. It has been proven to be an effective way to modify halide perovskite materials' bandgap by replacing A or B ions with other equivalent ions. However, C ions have much fewer choices and are limited to halogen anions or pseudohalides anions. We designed a series of new cubic perovskite structures through substituting C anions by superhalogen clusters anions (BeX3-,MgX3-,BX4-,AlX4-,SiX5-,PX6-,X=F,Cl), and studied their structures and properties in first-principles way. Calculations were performed by using the Vienna ab initio simulation package (VASP) based on density functional theory. The DOS (Density of States) and bandgaps were calculated to analysis properties of the new perovskite structures. The results show that BeX3-, MgX3- (X=F, Cl) and SiCl5- could not remain its structure which means these three clusters are not superhalogen anions anymore after doping. The size and symmetry of superhalogen anions have influences on the structures of doped perovskites. The superhalogen anion whose symmetry is higher and size is closed to I- ion induces less distortions to doped perovskite structures. Comparing to the VBM (Valence Band Maximum) and CBM (Conduction Band Minimum) of CsPbI3, superhalogen anions substitutions could change the compositions of CBM and VBM and bandgaps. The bandgaps of superhalogen anions partial substitutions in halide perovskite become smaller compared to structures with superhalogen anions substituting completely. We demonstrate that the CsPb(PCl6)3, with a direct-bandgap of 1.58eV located at M(0,0.5,0.5) point, could be a potential candidate materials for solar cells. Its CBM mainly is dominated by Cl 3p states, P 3s states and Pb 6p states. The other doped perovskites with wide bandgaps may have potential applications in transistors or memristors. We hope that these results could provide theoretical guidance for synthesis of new perovskite materials for solar cells.
      PubDate: 2017-10-20 00:00:00.0
       
  • Computational Insights into the Diels-Alder-alike Reactions of
           1-iodo-2-lithio-o-Carborane with Fulvenes
    • Authors: Mu Weihua; Ma Yao, Fang Decai, Wang Rong, Zhang Haina
      Abstract: Density functional theory (DFT) calculations at the B3LYP level, combining with the double-ζ valence polarized (DZVP) all-electron basis set as embeded in Gaussian 09 Program, were carried out to investigate the reaction mechanisms and substituent effect of Diels-Alder-alike reactions between 1-iodo-2-lithio-o-carborane and fulvenes. For maximum analogy with experimental conditions, all calculations were carried out in cyclohexane solution by using the IDSCRF solvent model, and all energies reported here had been adjusted adaptive to experimental temperature (353 K). According to presently obtained results, this reaction needs to go through a four-step process successively before the final carboranonorbornadiene products are formed. These four steps include forming carboryne intermediate by release of LiI fragment, interaction of carboryne with fulvenes, 1,2-σ migration of carboranyl, and the cycloaddition process. Among all four steps mentioned above, the 1,2-σ migration of carboranyl is predicted to be the rate-determining step (RDS), features an activation free energy barrier of 28.3 kcal·mol-1 under experimental temperature of 353K. A half-life of 8.7 hours converted from the RDS activation free energy barrier coincides well with corresponding 56% isolated yield of carboranonorbornadiene after reacted 8 hours. The LiI fragment is found to be vital in stabilizing most stationary points and driving the reaction ahead. The reaction mechanisms change little when the 4-H substituents on diphenylfulvenes (denoted reaction a) is replaced by 4-Me groups (denoted reaction b), but the corresponding RDS activation free energy barrier increased by 2.8 kcal·mol-1 (from 28.3 to 31.1 kcal·mol-1), transferring to a decrease in reaction rate of~50 times. The obvious slower reaction rate predicted in reaction b than in reaction a gives out correct trends with an experimental yield reduction of carboranonorbornadienes from 56% to 42%, and verifies the rationality of B3LYP results in these carboranyl-involved Diels-Alder-alike reactions. Natural bond orbital (NBO) analysis about corresponding reactants and stationary points shows similar electronic characteristics of this reaction with normal-electron-demand Diels-Alder (NEDDA) reactions, i.e., the fulvenes acts as electron donator when reacts with carboryne intermediate.
      PubDate: 2017-10-20 00:00:00.0
       
  • Research Progress of Photonic Crystal Solar Cells
    • Authors: Cong Zhao; Ying Ma, Yang Wang, Xue Zhou, Huizeng Li, Mingzhu Li, Yanlin Song
      Abstract: Photonic crystals have been widely used in solar cells in recent years, owing to the characteristic photonic bandgap, "slow photon" effect and a series of unique light control performance. The introduction of photonic crystals can greatly optimize the propagation and distribution of light in solar cells. Photonic crystals can improve the performance of solar cells from five aspects:(1) Photonic crystals constructed as back mirrors to reduce light loss and increase absorption efficiency of solar cell. (2) The interaction between photons and sensitizers can be enhanced by the "slow photon effect" of the photonic crystal band gap, which enhances the excitation efficiency. (3) Photonic crystal can be used as a scattering layer, increasing the propagation path of light in the material, forming a resonance enhancement mode in the absorption layer, and improving the light absorption efficiency. (4) Photonic crystals have large specific surface area. Especially three-dimensional photonic crystals can provide excellent carrier for sensitizer, which can effectively increase the load and activity of sensitized molecules and improve the photoelectric conversion efficiency (5) Photonic crystals can be used to reduce the dependence of solar cells on the incident angle of sunlight. For example, when the incident light is tilted, the blue shift of the Bragg position results in more overlap with the dye absorption peak, generating a higher efficiency that partially compensates the reduced photon flux due to light inclination. However, photonic crystals in different locations of the solar cell will improve or inhibit photoelectric conversion efficiency. Therefore, the fully understanding of light manipulation of photonic crystals and their correctly application is the key to improve the photoelectric conversion efficiency. Here, the applications of different types of photonic crystals in silicon solar cells and sensitized solar cells are summarized, at the same time the possible problems are also analyzed and reviewed.
      PubDate: 2017-10-10 00:00:00.0
       
  • Preliminary Study of Ni and P Low-doped Pd-based Electrocatalysts Toward
           Ethanol Oxidation Reaction in Alkaline Media
    • Authors: Zhu Chan; Hai Yang, Zhao Zhigang, Yang Yaoyue
      Abstract: Among currently reported anodic nano-alloy electrocatlysts for direct alkaline ethanol fuel cells (DAEFCs), the mass fraction (w) of co-catalysts is generally larger than 20%. This could increase the thickness of the catalyst layer in Membrane Electrode Assembly (MEA), which not only decreases the discharge voltage of fuel cells, also reduces the utilization of the noble metals such as Pt and Pd. To solve this problem, here we synthesized a series of Pd-Ni-P alloy electrocatalysts with ultra-low doping amount of Ni and P, using ca. 1.5 mg NaH2PO2 as reducing agent. To obtain different doping amount of Ni and P, the pH value of the synthetic solution was adjusted from 8 to 12 by 0.1 M NaOH. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) results showed that the mass fraction of Ni and P were low to 0.2% and 0.05%, respectively, when the pH value of the synthetic solution is 10. Transmission Electron Microscopy (TEM) images showed that nanoparticles were distributed evenly on the carbon base, and their mean particle sizes increased from ca. 3.78 nm to ca. 5.4 nm with alkalinity of synthetic solutions increasing. Cyclic Voltammograms in 0.5 M CH3CH2OH + 1 M NaOH solution revealed that the catalyst obtained under the pH 10 synthetic solution (hereafter denoted as Pd-Ni-P/C-pH10) gave a highest apparent current density of ca. ca. 2466 mA mg-1Pd, nearly 2.7 times in respect of that of the commercial Pd/C catalyst(BASF). Meanwhile, the durability of Pd-Ni-P/C-pH10 for ethanol oxidation was improved by ca. 2.8 times compared to commercial catalyst. Relative to pure Pd, the binding energy of Pd 3d5/2 of as-prepared catalysts all positively shifted, suggesting an obvious electronic interaction between Pd, Ni and P component in as-prepared catalysts. This interaction could led to a shift of the d-band center of Pd component, which may play a pivotal and dominated role in improving the catalytic performance for the ethanol electrooxidation in alkaline media.
      PubDate: 2017-10-10 00:00:00.0
       
  • Synthesis of γ-Fe2O3 nanocubes decorated graphene/CdS nanocomposites with
           enhanced photocatalytic performance
    • Authors: Wu Jiajia; Ji Zhenyuan, Shen Xiaoping, Miao Xuli, Xu Keqiang
      Abstract: With Prussian blue (PB) as the precursor for γ-Fe2O3, the tri-component CdS/RGO/γ-Fe2O3 photocatalyst was prepared through loading PB nanocubes and CdS nanoparticles on graphene oxide (GO) nanosheets, followed by a calcination process in inert atmosphere (N2). The content of γ-Fe2O3 in the CdS/RGO/γ-Fe2O3 photocatalyst can be adjusted by changing the loading amount of PB, and the cubic morphology of PB was maintained after the calcination. The composition, structure, morphology and light absorption of the as-prepared products were investigated by X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), Field emission scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Infrared spectroscopy (FT-IR), Raman spectroscopy and Ultraviolet-visible (UV-vis) spectroscopy. The photocatalytic activity of the ternary photocatalysts was evaluated by the degradation of the organic pollutant of Rhodamine B (RhB) under visible-light irradiation. It was found that the degradation process of RhB follows pseudo-first-order kinetics. Compared to the bi-component CdS/RGO photocatalyst, the tri-component CdS/RGO/γ-Fe2O3 exhibited greatly enhanced photocatalytic activity, demonstrating that the γ-Fe2O3 played an important role in the photocatalytic process. The CdS/RGO/γ-Fe2O3 composite with PB loading amount of 12 mg exhibits the highest photocatalytic degradation efficiency of about 99.8% and the highest apparent reaction rate constant (k) value of about 0.03289 min-1, which is almost 2.9 times and 1.8 times higher than that of CdS and CdS/RGO, respectively. This result indicates that a suitable loading amount of γ-Fe2O3 is important to optimizing the photocatalytic performance of the CdS/RGO/γ-Fe2O3 composites. Moreover, owing to the ferromagnetism of γ-Fe2O3, the CdS/RGO/γ-Fe2O3 photocatalyst could be easily separated from the reaction solution for recycling by a magnet. A possible photocatalytic mechanism was also proposed based on the Photoluminescence (PL) characterization and the active species capture experiment. It was demonstrated that the enhanced photocatalytic degradation properties of CdS/RGO/γ-Fe2O3 composites can be ascribed to the excellent conductivity of RGO and the construction of Z-scheme heterostructure between CdS and γ-Fe2O3, which facilitate the transport and separation of photogenerated carriers.
      PubDate: 2017-10-10 00:00:00.0
       
  • The Development and Applications of Bioorthogonal Cleavage Reactions
    • Authors: Wang Jie; Chen Peng
      Abstract: Bioorthogonal reactions enable us to study and manipulate biological processes under living conditions. As widely used and powerful tools, biorthogonal reactions are largely defined as "ligation reactions" that are used for labeling, tracing and capturing biomolecules. Recently, an emerging collection of biorthogonal "bond-cleavage reactions" have been developed and applied for biological studies, especially in releasing, activating and manipulating biomolecules. In this review, we will first summarize the characteristics and applications of these biorthogonal cleavage reactions. We will then focus on introducing diverse applications of biorthogonal cleavage reactions, including activation of prodrugs, rescue of intracellular protein activity, engineering of cell surface, among other interesting applications. Finally, the outlook of future development and applications of biorthogonal cleavage reactions will be discussed.
      PubDate: 2017-10-09 00:00:00.0
       
  • Characterization of steady-state current at nanoelectrodes
    • Authors: Ma Hui; Ma Wei, Yang Zheyao, Ding Zhifeng, Long Yi-Tao
      Abstract: Steady-state cyclic voltammetry has several advantages that make it extremely useful for characterization of ultramicroelectrodes, such as rapid electrode performance assessment and size determination. However, due to the nanoscale size effect, the slight variations in geometry of the nanoelectrodes can lead to significant perturbations in its performance. In this study, electrochemical experiments and finite-element simulations using COMSOL Multiphysics software were conducted to characterize the steady-state current dependence on electrode radii, geometries and recesses. To study the above characterics, the Pt nanodisk electrodes with different sizes were fabricated by using a laser-assisted wire pulling method on a P-2000 laser puller. Sluggish current responses were obtained for electrodes with a radius smaller than 80 nm in a 5 mM ferrocene (Fc) CH3CNelectrolyte solution containing 0.2 M Tetra-n-butylammonium hexafluorophosphate (TBAPF6). The experimental results agree very well with the simulations. It was discovered that the sluggish responses are due to the kinetically limited electron transfer resulting from the slow reaction rate relative to diffusion. Moreover, a minimum, constant steady state current value was measured once the RG value (i.e., the ratio of overall electrode radius to active electrode radius) was greater than 3. However, the current increased obviously with the RG value decreased below this value due to the enhanced mass transport. In addition, the steady-state voltammetric responses of recessed nanoelectrodes were investigated. It was found that the steady-state current decreased rapidly as the recess depth increased and a classical sigmoidal shape current response was obtained recovering from a sluggish current response. The unique current responses resulted from the restriction of the diffusion of redox molecules in a deep channel to the electrode. To verify the correlation of recess depth to current response, a model was built based on two-dimensional axial symmetry and the obtained simulation results were consistent well with the experimental data. Our findings offer an understanding on the relationship between the nanoelectrode geometry and steady-state cyclic voltammetry, which can provide insight into their electrochemical behaviors.
      PubDate: 2017-10-09 00:00:00.0
       
  • Asymmetric Carbonyl Allylation of Aldehydes with Allylic Alcohols under
           the Sequential Catalysis of Palladium Complex and Chiral Phosphoric Acid
    • Authors: Zhang Zijing; Tao Zhonglin, Arafate Adele, Gong Liuzhu
      Abstract: The asymmetric carbonyl allylation of aldehydes with allylmetal reagents presents one of the most efficient and straightforward methods for the synthesis of optically active homoallylic alcohols, which have found widespread applications in organic synthesis. As such, a wide range of chiral catalysts, including Lewis acids, Lewis bases and Brønsted acids have been reported to enable highly stereoselective carbonyl allylation of aldehydes with allylmetal reagents. Among them, chiral phosphoric acid-catalyzed carbonyl allylation of aldehydes with pinacol allylboronates represents a promising method, whereas an additional operation required for the preparation of allylboronates from allyl halides or highly active allylmetallics imposes some constraints on the carbonyl allylation process. In this context, the asymmetric addition of allylboronates, in situ generated from palladium-catalyzed allylborylation, to aldehydes has been reported, while stoichiometric amounts of chiral diboronate reagents are basically required. Allylic alcohols are readily available feedstock. The direct use of allylic alcohols as starting materials in asymmetric allylborylation of carbonyls is highly valuable. Herein, we will report an asymmetric carbonyl allylation of aldehydes with allylic alcohols in the presence of octamethyl-2,2'-bi(1,3,2-dioxaborolane) under the sequential catalysis of a palladium complex and chiral phosphoric acid. The presence of 2.5 mol% (η3-C3H5)2Pd2Cl2, 5 mol% P(OPh)3 and 10 mol% chiral phosphoric acid B*H-1 enabled 4-nitrobenzaldehyde 2a to smoothly undergo the asymmetric carbonyl allylation reaction with 2-buten-1-ol 1a and octamethyl-2,2'-bi(1,3,2-dioxaborolane), giving rise to the desired homoallylic alcohol product 3aa in a 99% yield and with >20:1 dr and 92% ee. Under the optimal conditions, the generality for allylic alcohol substrates was investigated to reveal that the installation of either of saturated alkyl substituents, carbon-carbon double bond or heteroatom group in the allylic alcohols allowed the target products (3ca-3fa, 3ha-3ja) to be obtained in high yields and with excellent stereoselectivities. A (Z)-allylic alcohol and branched allylic alcohol were also able to generate the target products (3ba, 3ga), successfully. Although cinnamic alcohols participated in a clean reaction, relatively lower yields and stereoselectivity were delivered (3ka and 3la). The examination of aldehydes suggested that the introduction of either electronically deficient or rich substituents to the benzene ring of benzaldehydes was tolerant and led to corresponding homoallylic alcohols in excellent yields and stereoselectivities (3ab-3ak and 3m), with the exception of o-anisaldehyde (3al). In addition, 2-naphthaldehyde, aliphatic aldehydes and enals are all good substrates and provide high yields and enantiomeric excesses as exemplified by 3-phenylpropanal and 4-methoxycinnamaldehyde (3an-3ap).
      PubDate: 2017-10-09 00:00:00.0
       
  • Investigation on CH3SH Desulfurization Mechanism at the Edge site of
           Co-doped MoS2 Cluster
    • Authors: Zhang Tian; Guo Chen, Wei Shuxian, Wu Zhonghua, Han Zhaoxiang, Lu Xiaoqing
      Abstract: With the advent of increasingly stringent regulations on sulfur containing in oil products, desulfurization of crude oil has become an urgent task for petrochemical production. Molybdenum sulfide (MoS2) have been extensively studied as one of the most efficient hydrodesulfurization catalysts. Co-doped molybdenum sulfides are usually used in desulfurization processes of sulfur-containing compounds,in which the transition metal Co could promote its catalytic performance. Herein, density functional theory was employed to investigate the formation of coordinative unsaturated active sites (CUS) and the catalytic desulfurization process of methanethiol (CH3SH) at the Co-doped MoS2 triangular clusters. Results showed that Co was not the effective reaction site on hydrogenation process, and Mo and S atoms acted as the active sites of hydrogen dissociation during the formation of CUS sites, followed by the H2S generation and desorption. The charge population analyses showed that Co promoted the hydrogenation process indirectly. CH3SH prefered to be adsorbed at the TopCo site with a high adsorption energy of -1.44 eV. The charge population and frontier orbitial analyses illustrated that Co can alter the distribution of the surface atoms' charge and the LUMO orbital of CUS and showed the strong electrophile and thus strengthening the CH3SH adsorption. When CH3SH was adsorbed at the Co-doped MoS2 clusters, electrons transfered from CH3SH to the surface atoms of MoS2. In this work, three desulfurization pathways of CH3SH at the Co-doped MoS2 were investigated, namely, the C-S bond initial scission, the S-H bond initial scissions, and the C-S and S-H scissions simultaneously. The competitive route during the CH3SH desulfurization process started with the S-H and C-S bond scissions successively, followed by the methane formation in the terms of thermodynamics and kinetics, and the formation of methane was the rate-determining step with the energy barrier of 1.51 eV.
      PubDate: 2017-10-09 00:00:00.0
       
  • Advances on Nitrogen-centered Radical Chemistry:A Photocatalytic N-H Bond
           Activation Approach
    • Authors: Song Hao; Liu Xiao-Yu, Qin Yong
      Abstract: Nitrogen-centered radicals are highly reactive intermediates, which provide new opportunities for designing new chemical reactions and preparing nitrogen-containing molecules. Direct generation of nitrogen-centered radicals via activation of N-H bonds under photocatalytic conditions has emerged as a green, efficient, and economical process, where significant progress has been made with methodology development in very recent years. In this paper, we highlight the important advances in this area that were reported since 2016.
      PubDate: 2017-09-29 00:00:00.0
       
  • Progress in Organic Fluorescent Thermometers
    • Authors: Qin Tianyi; Zeng Yi, Chen Jinping, Yu Tianjun, Li Yi
      Abstract: Temperature is a basic physical parameter. Accurate measurement of temperature is of importance to scientific research and to industry production and life. Fluorescent temperature sensing, as a new method for temperature measurement, has received much attention because of its high resolution, fast response and observation with bear eyes, etc. Organic fluorescence probes are firstly used in fluorescent temperature sensing due to the versatility of structures, easier modification, and the consequent multiple spectral responses. The fluorescent thermometers can be applied in the temperature sensing of large area, microfluids, biological systems and so on, which make them attractive in the field of fluorescent probes research. In recent years, fluorescent thermometers based on organic fluorescence probes have made remarkable progress. Two major kinds of organic fluorescence thermometers are classified in this review based on the response of fluorescence wavelength, one is the single-wavelength response type, and the other is the ratiometric one. For the single-wavelength type, there are thermal-quenching and thermal-enhancing fluorescence thermometers based on the temperature-dependent trend of emission intensity. At the earlier stage, organic chromophores with high fluorescence quantum yields are adopted as the thermal quenching fluorescence thermometer, and recently a series of conformation-regulated organic thermometers based on dendritic structure and aggregation-induced emission chromophore was developed. Thermal response macromolecules including PNIPAM, PEG and DNA are widely used to create thermal responsive microenvironment to regulate chromophore emission, and then develop thermal-enhancing fluorescence thermometers. Ratiometric fluorescence thermometers show better sensitivity and accuracy than single-wavelength ones due to their self-correction property based on the different thermal-response of emission at two wavelengths. Several kinds of ratiometric sensing systems have been developed, which are based on dye-copolymerized/doped polymer systems, monomer-excimer ratiometric emission, chromophores with thermal transition of local excited state and twisted intramolecular charge transfer state, and chromophores with thermal-induced crystal transfer. In this review, recent advances of organic fluorescence thermometers mentioned above will be presented and the challenges and the future development will be discussed.
      PubDate: 2017-09-29 00:00:00.0
       
  • Photocatalytically Renewable Electrode for On-Line Regeneration under
           Visible Light Irradiation and Real-Time Monitoring of Living Cells
    • Authors: Duo Huanhuan; Liu Yanling, Wang Yawen, Tang Yun, Huang Weihua
      Abstract: Electrode fouling and passivation is an inevitable problem which seriously affects the electrode performance in cell culture and detection. Construction of photocatalytically renewable electrode by combination of nanophotocatalysts with electrochemical sensing materials could provide a promising approach for highly efficient renewal of electrode surface without damaging its micro-or nanostructures. However, the reactive oxygen species generated during photocatalysis always cause damages to cells being adhered or cultured on the electrode surface, which precludes on-line renewal of electrode during cell culture and detection. To address this issue, based on the visible light-induced renewable electrode (poly(3,4-ethylenedioxythiophene) (PEDOT)-modified TiO2/CdS nanocomposites electrode we previously developed, a thin layer of gelatin hydrogel was spin-coated on the electrode in this work to realize efficient electrode renewal under visible light irradiation during the culture and detection of living cells. The optimized thickness (ca. 2 μm) of gelatin hydrogel was obtained by spin-coating under 3000 rpm. Benefitting from the network structure of gelatin hydrogel and the renewable performance of PEDOT@CdS/TiO2 nanocomposites, the gelatin coating efficiently blocked the diffusion of biomacromolecules from the bulk medium to the electrode surface and thus significantly diminished the fouling caused by these macromolecules, while the pollutants derived from small molecules could be efficiently degraded under visible light irradiation. Meanwhile, gelatin coating did not induce obviously decline in detection sensitivity, and a low detection limit of 4.2 nM (S/N=3) could obtained towards electrochemical detection of nitric oxide (NO). Most importantly, the gelatin layer efficiently blocked the ultrashort-lived but highly reactive oxygen species such as OH· (generated by photocatalytic process) diffusing from the electrode surface to the cells, and the damages to the cells caused by these highly reactive species could be therefore significantly decreased. The results from live/dead cell staining demonstrated that almost all the cells (> 95%) cultured on gelatin-coated electrodes maintain their viability when the electrode was irradiated by visible light for 6 hours, while a considerable part of cells (> 40%) culture on the uncoated electrode lost their viability under the same conditions. These features allowed on-line renewal of the electrode during cell culture and detection as well as real-time monitoring of NO released from the human umbilical vein endothelial cells (HUVECs).
      PubDate: 2017-09-25 00:00:00.0
       
  • Fluorescent Nanoprobe for Detection and Imaging of Nucleic Acid Molecules
    • Authors: Yang Limin; Liu Bo, Li Na, Tang Bo
      Abstract: Nucleic acids, including deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), play important roles in normal or abnormal life activities. DNA is an important genetic material and carrier of genetic information. It plays an important role in cell division, biological development, mutation, cancer, etc. RNA includes mRNA, tRNA, microRNA (miRNA) and small RNA. Tumor-associated mRNA has been widely used as a specific marker to assess the migration of tumor cells, and its expression level is related to the tumor burden and malignant progression. MiRNA is a non-coding small molecule RNA that regulates at least 30% of the genes. MiRNA is involved in most of the biological process, such as proliferation, differentiation, senescence, migration and apoptosis. The abnormal expression of DNA, mRNA and miRNA is closely associated with the occurrence and development of multiple diseases. Therefore, developing accurate and effective methods for detecting nucleic acid molecules is of great significance for studying the function of nucleic acid regulation and achieving the early detection and treatment of diseases. Fluorescence detection method and imaging technology provide powerful tools for real-time and accurately detecting nucleic acid molecules due to their high sensitivity and temporal resolution. Fluorescent nanoprobe has many advantages such as good biocompatibility, good solubility and so on. It has been widely used in the detection of nucleic acid molecules for further understanding the roles of nucleic acid in many diseases. In this review, we have showed the roles of various nucleic acid molecules in life activities and illustrated the advances in the development of fluorescent nanoprobe for detection of disease-related DNA, mRNA and miRNA in live cells and in vivo in recent years. The preparation of these nanoprobe, detection mechanism and imaging application were also presented. Finally, the challenge and future development of constructing new fluorescent nanoprobe for nucleic acids detection were proposed.
      PubDate: 2017-09-18 00:00:00.0
       
  • Single Nanoparticle Sensing Based on Optical Microscopy
    • Authors: Wang Yongjie; Wang Wei
      Abstract: Single nanoparticle sensing (SNS) is an emerging research field which utilizes single nanoparticles as individual nano-sensors to acquire the qualitative and quantitative information of the analytes in a localized and microscopic sample environment. Both the molecular recognition and signal transduction take place at the surface of a single nanoparticle. Versatile kinds of optical microscopy, such as dark-field microscopy and fluorescence microscopy, are often applied to locating the nano-sensor, and to accessing and analyzing the optical signal it reports. Compared to traditional sensing mechanisms that rely on ensemble nanomaterials, SNS has demonstrated its excellent sensitivity down to single molecule detection by focusing in extremely small volumes in the range of aL~pL. Simultaneous monitoring on many individual nano-sensors in a nano-array further allows for high-throughput and multiplex analysis. More importantly, single nanoparticles can be easily introduced to microscopic and dynamic systems such as living cells to probe specific analytes with high temporal and spatial resolution while maintaining the excellent sensitivity. In this review, we begin with a brief introduction on the history and development of SNS, which is followed by its major features. We subsequently survey the recent progresses in this field in the past five years, focusing on the different sensing principles, single nanoparticle counting and single nanoparticle tracking. We finally provide our perspectives that further developments on nano-probes, optical imaging techniques and data analysis are critical to the growth and applications of SNS in broad fields.
      PubDate: 2017-09-18 00:00:00.0
       
  • Real-time monitoring skin cell alignment on nano-grooves using electric
           cell-substrate impedance sensing (ECIS)
    • Authors: Jin Tongyu; An Yu, Zhang Fan, He Pingang
      Abstract: Cell alignment plays a crucial role in the repair and regeneration of tissues, which is caused by the "contact guidance" of micro/nano structures. In this paper, the nano-grooves with 200 nm in width, 400 nm in period and 75 nm in depth were fabricated on gold substrate with the technique of nanoimprint to simulate the extracellular matrix (ECM). Electric cell-substrate impedance sensing (ECIS) was employed firstly to real-time monitor cell alignment of human foreskin fibroblasts (HFF) and human immortal keratinocyte cells (HaCaT) on nano-grooves, which are two important functional cell types in skin wound-healing. The cell images displayed that the nano-grooves could induce the alignment of HFF cells, in which, the cell arrangement along the direction of nano-grooves occurred prior to the cell elongation. While, the nano-grooves couldn't influence the morphology of HaCaT cells, and their adhesion and spread were delayed. In the ECIS monitoring, HFF and HaCaT cells both presented increased normalized impedance (NI) values at their respective characteristic frequencies of 977 Hz and 1465 Hz on nano-grooves and flat electrodes with the prolongation of culture time during 24 h and the increasing trends of NI values were also similar:in the first 6 h, NI values increased faster, and then, the increasing rates declined obviously. HFF cells on nano-grooves generated more intense impedance signals with a larger distinction of increasing rate than those on flat electrodes, indicating that the nano-grooves could promote the adhesion and spread of HFF cells and the directional arrangement had a larger impact on the variation of NI values than cell elongation. While, HFF cells adhered and spread in random directions, leading to the reduced difference in increasing rate of NI values. The NI values of HFF cells was further correlated with cell alignment, showing the enhanced impedance responses with the rising percentage of aligned cells. More importantly, there was a good linear correlation between NI values and the percentage of cells arranging along the direction of nano-grooves. In contrast, HaCaT cells had smaller NI values on the nano-grooves with the similar increasing rates, compared to the flat electrodes, revealing that the nano-grooves were less suitable for the adhesion and spread of HaCaT cells with almost no change of cell morphology, and the cell adhesion could cause more obvious variation of NI values than cell spread. Our research would provide a support for the development of complex cell sensors based on ECIS and its application in clinical research field.
      PubDate: 2017-09-08 00:00:00.0
       
  • Nanoplasmonic Biological Sensing and Imaging
    • Authors: Su Yingying; Peng Tianhuan, Xing Feifei, Li Di, Fan Chunhai
      Abstract: The localized surface plasmon resonance of metal nanoparticles is the collective oscillation of electrons on particle surface. The localized electromagnetic interaction brings a series of novel functions and applications. Plasmonic nanomaterials have been the significant part of nanophotonics, since its' localized surface plasmon resonance (LSPR) can focus incident phonons at the nanoscale surface. The unique plasmonic property is highly sensitive to their size, shape, coupling between particles as well as local dielectric environment. These properties can be utilized for the development of new biosensing and bioimaging applications. To date, many LSPR sensing strategies have been developed with outstanding measurement capabilities, enabling detection down to the single-molecule level, including LSPR-based sensing, surface-enhanced Raman scattering, metal-enhanced fluorescence, dark-field light-scattering, metal-mediated fluorescence resonance energy transfer. Moreover, the unique optical stability of plasmonic nanoparticles enables them as ideal probes in cellular imaging. Here, recent examples on application of plasmonic nanostructures in sensing and bioimaging are summarized, and perspectives are provided as well.
      PubDate: 2017-09-06 00:00:00.0
       
  • Progress and Perspectives on High Voltage, Flame Retardant Electrolytes
           for Lithium-Ion Batteries
    • Authors: Xia Lan; Yu Linpo, Hu Di, Chen Z. George
      Abstract: The electrolyte is an indispensable constituent in lithium ion batteries, and its role conducts electricity by means of the transportation of charge carries between the pair of electrodes. Its properties directly affect the energy density, cycle life and safety of the battery. However, there are two major challenges to using carbonate-based electrolytes in recent lithium ion batteries (LIBs) to further increase the energy density of the devices without compromising the safety. One is that carbonate-based electrolytes are not sufficiently stable at the positive electrode, and the other is their relatively high flammability. Therefore, developing high voltage and flame retardant electrolytes for LIBs is highly desired. Herein, we review the recent progress and challenges in new electrolytes, focusing on high-voltage electrolytes, flame retardant electrolytes and highly concentrated electrolytes. Among the reported electrolytes, highly concentrated electrolytes are worth a special attention, showing various unusual functionalities, for example, high oxidative stability, low volatility, high reductive stability, and non-corrosive to Al. These special properties are totally different from that of the conventional 1 M LiPF6/EC-based electrolytes, which are result from solution structures. A discussion is also provided in this review on the prospects of further development of new electrolytes for LIBs.
      PubDate: 2017-09-06 00:00:00.0
       
  • Electrochemical Assay for Acetylcholinesterase Activity Detection Based on
           Unique Electro-catalytic Activity of Cu (II)-thiol Coordination Polymer
    • Authors: Wang Qin; Nie Zhou, Hu Yufang, Yao Shouzhuo
      Abstract: Acetylcholinesterase (AChE), as a key enzyme, ubiquitously exists in the peripheral nervous system. It mainly functions terminating neurotransmission at the cholinergic synapse through the rapid hydrolysis of acetylcholine (a neurotransmitter) into choline and acetate, which is intimately related to Alzheimer's disease, inflammatory processes, and nerve-agent poisoning. In this study, we developed a novel electrochemical method for probing AChE activity and screening its potential inhibitor based on the in-situ formation of thiocholine-Cu(Ⅱ) coordination polymer (denoted as TCh-Cu(Ⅱ) CP). The detection mechanism is on the basis of the concept, that is, AChE could catalyze the hydrolysis of its substrate acetylthiocholine (ATCh) to produce a thiol-compound thiocholine (TCh). Subsequently, TCh reacted with Cu(Ⅱ) to form a positively charged TCh-Cu(Ⅱ) CP via S-Cu bond. Since the graphene (GO) is a negative compound due to its plenty of carboxyl groups, TCh-Cu(Ⅱ) CP could be absorbed onto the graphene-modified glassy carbon electrode (GO/GCE) via electrostatic interaction. What's more, the CP/GO/GCE can electro-catalyze the O-phenylenediamine (OPD), generating a high current signal. We also conducted a series of experiments to verify the formation and electro-catalysis of TCh-Cu(Ⅱ) CP and investigate the selectivity of the TCh-Cu(Ⅱ) CP-based assay for AChE. As a result, it is clearly observed that the electrochemical response gradually increases with the increasing concentrations of AChE (0.05-100 mU/mL) and a detection limit of our method is estimated to be~0.03 mU/mL (S/N=3). Furthermore, compared to the traditional methods, our electrochemical assay has more simple detection procedure with better sensitivity and selectivity and has great potential in applications in many important areas, such as neurobiology, toxicology, and pharmacology, especially for the effective treatment of Alzheimer's disease.
      PubDate: 2017-09-04 00:00:00.0
       
  • Optical Sensors Based on Optical Interference of Nanoporous Film
    • Authors: Wang Yafeng; Yang Qian, Su Bin
      Abstract: Optical sensors are devices that transform the interaction between medium and analyte to optical signal. Optical interference is a technique that has been widely applied in optical sensors, which is label-free, fast and non-invasive. Light reflected from the top and bottom surfaces of single layer film, or each interfaces of multilayer film in optical sensors leads to constructive and destructive fringes of the optical interference pattern. Nanoporous films with large surface-to-volume ratio are beneficial to improve the sensitivity and lower the limit of detection of the sensors, which is typically used in the form of single layer, double layer or multilayer (usually served as photonic crystal). In this article, we introduce and review the applications of nanoporous films of silicon, anodic aluminum oxide, titanium dioxide and metal-organic framework in optical sensors based on the optical interference. A perspective of developments in this research field is also provided.
      PubDate: 2017-09-04 00:00:00.0
       
  • Highly Sensitive Detection of Mercury Ion Based on Plasmon Coupling
    • Authors: Qian Guangsheng; Zhao Wei, Xu Jingjuan, Chen Hongyuan
      Abstract: Mercury is very harmful to the environment and human health even at low concentration. Methods for sensitive detection of mercury ion (Hg2+) have increasingly been developed over the past decade owing to the rapid development in nanotechnology. However, the limits of detection (LODs) of these methods are mostly not satisfactory enough to meet the demand of monitoring trace amounts of mercury ion. DNA thymine (T bases) can react with the mercury ion to form T-Hg2+-T structure, and this interaction has been proved to be much more stable than the interaction between thymine and its com-plementary adenine (A bases). Based on this principle, a series of ultra-sensitive DNA-based colorimetric biosensors, mostly using Au nanoparticles (AuNPs) as DNA carriers, have been designed for detection of mercury ion. In this study, we report a new strategy for highly sensitive Hg2+ detection based on Hg2+-induced AuNPs assembly. AuNPs of different sizes (s-AuNPs of 18 nm and c-AuNPs of 52 nm) were modified with oligonucleotides containing a sequence of continuous T bases. In the presence of Hg2+, s-AuNPs would be bound to c-AuNPs in the solution owing to oligonucleotide hybridization, forming a core-satellites nanostrucure. This process was accompanied by a color change of the scattering light from green to orange as observed under dark-field microscopy and a corresponding distinct scattering peak shift. The scattering spectra of the AuNPs were obtained using a spectroscopic system which was established autonomously. The scattering peak shift of color-changed spots corresponded with Hg2+ concentration. It was increased linearly with logarithm of Hg2+concentration over a wide range from 1 pmol/L to 1 nmol/L, with the correlation coefficient of 0.983 (R2=0.983), and the detection limit of Hg2+ was estimated to be 1 pmol/L. Other metal ions, such as Ag+, K+, Ca2+, Mg2+, Zn2+, Cd2+, Fe2+, Pb2+, Ni2+, Mn2+, Al3+, induced negligible scattering peak shifts for AuNPs under the same conditions, which showed that this strategy exhibited excellent selectivity towards Hg2+. Moreover, satisfactory results were obtained when the proposed approach was applied to detect Hg2+ in real samples with recoveries of 98.7%~103.1% and 105.6%~108.2% for river water and tap water, respectively.
      PubDate: 2017-09-04 00:00:00.0
       
  • Experimental research of protein translocation using solid-state nanopore
    • Authors: Sha Jingjie; Xu Bing, Chen Yunfei, Yang Yanjing
      Abstract: For proteins' diverse range of structural and functional features, they are important populations of biomolecules within organisms. Common methods to detect proteins are with the help of fluorescence or enzyme. Due to the advantages like lable-free and single-molecule detection, nanopore technology provides a novel platform for proteins' characterization. In this experiment, the patch clamp amplifier is used to apply the voltage and acquire the tiny current blockage. The Si3N4 membrane drilled with a nanopore separated the buffer solution into two sides:cis and trans. When the voltage applied into the buffer solution, charged proteins would been driven through the pore from one side to the other. Then, a series of current blockages could be obtained. By analysing these data, the size and conformation of the biomolecules could be acquired. In this paper, we using solid-state nanopore detected single protein and protein-protein complexes. The nanopore was characterized firstly. Then, both the applied voltage and the pH of the electrolyte solution were regulated. Under the low voltage, the sample proteins could be regarded as a rigid spheroid, and the dwell time is decreased with the voltage increasing. It was found that, the charges carried by proteins could be improved by higher pH of buffer solution, so that the dwell time would been shortened. Furthermore, based on the high specific between the antigen and antibody which are essentially proteins, the translocation events before and after the addition of specific antigen into the solution with antibody were compared. Results showed that the relative current drop of the complex is larger than the pure antibody, implying that the antigen has been bound into the antibody. Due to the difference of excluded volume, the antibody and antigen-antibody complexes could be distinguished by the solid-state nanopore. In the future, the nanopore technology is promising to be applied into the recognition of multiply proteins and protein-protein interaction. Keywords:Bovine serum Albumin (BSA), Antigen, Antibody, Solid-state nanopore, Single-molecule detection.
      PubDate: 2017-09-04 00:00:00.0
       
  • Research progress in thermoelectric materials for sensor application
    • Authors: Gang Liu; Tie Wang
      Abstract: Sensor as one core component of modern intelligent industrial, have attracted enormous attention due to exert a significant influence on the design and function of key products. In a paper, the thermoelectric materials were reported to play a key role for the high sensitivity, response and stability to make a sensor, such as silicon, carbon, lead, tellurium, precious metal, organic and catalysis based thermoelectric materials. Because of high purity silicon, the silicon-based thermoelectric materials were extremely efficient in sensor data processing and transmission. Carbon-based thermoelectric materials as structure of the sensor, there are two important examples. One is Graphene is applied to a sensor because of the high conductivity, with the product in Graphene layer. It is benefit for sensor signal transmission, increase sensitivity.Other is carbon nanotube, which feature structure is flexible, can knit the something as we need. With the sensor miniaturization, like silk, carbon nanotubes, need at the formation of processing and weaving, it was so large-area film that more widely harness industrial potential.Lead-based thermoelectric materials mainly used in infrared sensors, because of the nature lead, which can be sensitive to infrared specially.Telluride-based thermoelectric materials, especially Bismuth Telluride and Antimony Telluride, it can form PN junction to apply in the side of flexible sensor. It used to detect a pulse and can be promote as a mature product.The precious metals-based thermoelectric materials, gold or silver, it can improve conductivity of as the dopant. It is an important direction of development that the precious metals-based integrated into the organic thermoelectric materials. It can also adjust the sensitivity of Miniaturization Sensor. Organic thermoelectric materials benefited for Miniaturization Sensor due to the good stability and variability. Moreover, Copper-bismuth alloy -based thermoelectric materials were used to make gas sensors are an attempt to greatly, which broaden the application of thermoelectric materials in the field of sensors. Generally speaking, as the Miniaturization Sensor, the inorganic thermoelectric materials had the feature of high electrical conductivity in order to enhance the sensitivity of Sensor, whereas the organic thermoelectric materials had high stability in order to maintain the stability of Sensor.
      At present, high ZT were obtained by the low dimensional thermoelectric material, whose thermoelectric performance can be effectively improved. At the same time, the development trend of Sensor is miniaturization. They have a common development direction. It is benefit to each other. The low dimensional thermoelectric materials will promote the advanced sensor development. Miniaturization Sensor aimed at the space -saving through the high integrated function. For example, thermoelectric materials with nano-structure of quantum dots, lines, as well as body shape, which adopted to be effectively arranged and assembled, can be achieved with a material that carries a variety of functions and improve the practical value of the sensor.
      PubDate: 2017-09-04 00:00:00.0
       
 
 
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