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Progress in Chemistry 2012, No.11 Previous issue Next issue

In this issue:

Review
Theoretical Foundation and Limitation of Two-Step Anodizing Technology
Zhu Xufei, Han Hua, Qi Weixing, Lu Chao, Jiang Longfei, Duan Wenqiang
2012, 24 (11): 2073-2086 |
Published: 24 November 2012
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Abstract
Two-step anodizing technology (TSAT) has been used widely in the assembling process of porous anodic alumina and porous anodic TiO2 nanotubes. However, the theoretical background and foundation of TSAT are still unclear because of the ambiguous interpretations about the pore generation. A detailed introduction to the origin and theoretical foundation of the TSAT and imprinting technology is presented. The unexplainable experiment phenomena in two-step anodizing process which traditional theories (e.g. the field-assisted dissolution or ejection) can not explain and the limitation and using conditions of the TSAT and imprinting technology are analyzed. The explanation for these conflicting phenomena reported in the published references is given via the oxygen bubbles model. The important effect of the oxygen bubbles mould and the viscous flow of barrier oxide on the formation of columnar and regular channels is emphasized. The electronic current, ionic current and oxygen bubble mould will play an important role in the structural modulation of porous anodic alumina and porous anodic titania nanotubes. The present views may be helpful to understand the mechanism of porous anodic titania and facilitate the assembling of diverse nanostructures for extensive application in photocatalysis and solar batteries. Contents
1 Introduction
2 Origin and theoretical background of two-step anodizing technology
3 Limitation and using conditions of imprinting technology
4 Unexplainable experiment phenomena in two-step anodizing process
5 Explanation for above conflicting phenomena through the model of oxygen bubbles
6 Conclusions
Anti-Icing Coatings: From Surface Chemistry to Functional Surfaces
Li Hui, Zhao Yunhui, Yuan Xiaoyan
2012, 24 (11): 2087-2096 |
Published: 24 November 2012
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Abstract
Icing on substance surfaces is known to cause serious problems that often leads to costly safety issues in the fields of transportations, astronavigation and aeronautics, power transmission and telecommunication. Although currently available de-icing techniques by mechanically removing, heating or spraying chemicals are generally effective, they can result in energy consumptions and environment pollutions. Meanwhile, the method of anti-icing coatings to protect the substance surfaces is considered as an effective and available way showing highly potential applications, which has aroused extensive interest among scientists in recent years. In this review, the mechanism of the coatings to prevent icing and the basic factors that affect the ice adhesion on substance are briefly introduced. Furthermore, the research progresses and prospects of various anti-icing coatings are particularly summarized, including sacrificial coatings, icephobic coatings and superhydrophobic coatings. Moreover, the preparation methods of these anti-icing coatings are emphatically described. It has been proved that icephobic or superhydrophobic coatings containing fluorine and silicone with low surface energy can be applied to anti-icing by shortening the attaching time of water droplets on the substrates and reducing the ice adhesion strength. The challenges and the prospective tendency of anti-icing coatings are also given based on the current researches. Contents
1 Introduction
2 Anti-icing principles of coatings
3 Research status in anti-icing coatings
3.1 Sacrificial coatings
3.2 Icephobic coatings
3.3 Superhydrophobic coatings
4 Challenges for anti-icing coatings
5 Conclusions
Kinetics of Gas-Phase Radical Reactions Using Photoionization Mass Spectrometry with Synchrotron Source
Chu Genbai, Chen Jun, Liu Fuyi, Sheng Liusi
2012, 24 (11): 2097-2105 |
Published: 24 November 2012
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Abstract
Gas-phase radicals can react rapidly with various gaseous molecules, which play a vital role in catalyzing reactions in atmospheric, combustion and interstellar chemistry. A range of experimental techniques such as fluorescence and absorption spectrometry have been employed to study the reaction processes of gas-phase radicals and acquired some important results. Despite of the sufficient sensibility in the measurement of transient species, most of these techniques are limited to small radicals with small molecules, inaccessible to bigger radicals or multiplexed detection. Lately, a combination of flow reactor, flash laser photolysis and synchrotron radiation (SR) photoionization mass spectrometry (PIMS), serves as a universal, multiplexed, selective and sensitive method, ideal for the chemical kinetics study. Pulsed photolysis laser is used to initiate radical reaction, SR vacuum ultraviolet (VUV) light source to ionize the molecules emerging from the side pinepole and mass spectrometer to detect multiple species in the reactions (especially many-atom species). A plenty of original works such as the studies of CN, OH and alkylperoxy radical reactions have been done using double-focusing mass spectrometer or time-of-flight mass spectrometer and identified to be in fair agreement with the previous methods. Furthermore, the extra ordinary capability of time- and energy- resolution can be widely applicable in the kinetics study of some important radicals such as alkylperoxy and aromatic radicals in atmospheric, combustion,and interstellar chemistry. Contents
1 Introduction
2 Experimental techniques for radical kinetics
2.1 Absorption, fluorescence and infrared spectrum
2.2 Mass spectrometry (MS)
2.3 PIMS with flash laser photolysis and flow reactor
3 Application of PIMS
3.1 Cyano radical reactions
3.2 Alkylperoxy and alkenylperoxy radicals
3.3 OH radical reactions
3.4 Other radicals
4 Conclusion and outlook
Development of Organic Polymer/Inorganic Semiconductor Hybrid Solar Cells
Zhang Huijing, Hou Xin
2012, 24 (11): 2106-2115 |
Published: 24 November 2012
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Abstract
Organic polymer/Inorganic semiconductor hybrid solar sell is a kind of solar sell which was prepared by a composite of organic conjugated polymer and inorganic semiconductor as the main raw material. The working mechanism of Organic polymer/Inorganic semiconductor hybrid solar sell was introduced in this paper. The influencing factors on the power conversion efficiency (PCE) of the hybrid solar cell, such as the choice of the conjugated polymer, the morphology of hetero-junction, the thickness of the photosensitive layer, the choice of the inorganic semiconductor and its modification, and annealing of the cell, were reviewed in detail. At last, the prospect of hybrid solar cell was also presented, more attention should be focused on the modification of available conjugated polymer or the synthesis of new conjugated polymers to improve the power conversion efficiency (PCE) of the hybrid solar cell in the future. Contents
1 Introduction
2 Working principle of hybrid solar cells
3 Development of hybrid solar cells
3.1 Choice of conjugated polymers
3.2 Morphology of heterojunction
3.3 Choice of inorganic semiconductors and their modification
3.4 Thickness of photosensitive layer
3.5 Annealing of hybrid solar cells
4 Outlook
Photocatalytic Reduction of CO2 on TiO2 Catalysts
Wang Huixiang, Jiang Dong, Wu Dong, Li Debao, Sun Yuhan
2012, 24 (11): 2116-2123 |
Published: 24 November 2012
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Abstract
The technology of photocatalytic reduction of CO2 has potential applications and good prospects for the development in the management and utilization of CO2. This paper briefly reviews TiO2 catalytic materials studied for photocatalytic reduction of CO2, including pure TiO2, supported TiO2, metal-modified TiO2, compound semiconductor TiO2, and organic photosensitized TiO2 catalysts. In addition, the photocatalytic activities of the catalysts are discussed. Contents
1 Introduction
2 Mechanism of photocatalytic reduction of CO2
3 Research progress in photocatalytic reduction of CO2
3.1 Photocatalytic reduction of CO2 on pure TiO2
3.2 Photocatalytic reduction of CO2 on supported TiO2
3.3 Photocatalytic reduction of CO2 on metal-modified TiO2
3.4 Photocatalytic reduction of CO2 on compound semiconductor TiO2
3.5 Photocatalytic reduction of CO2 on organic photosensitized TiO2
4 Conclusion and outlook
Visible-Light Responsed Bi2WO6 Photocatalysts
Feng Yan, Wu Qingsong, Zhang Guoying, Sun yaqiu
2012, 24 (11): 2124-2131 |
Published: 24 November 2012
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Abstract
Bi2WO6 materials exhibit excellent visible-light photocatalytic activity due to the narrow band gap and special layered structure. This paper summarizes the research achievements on the improvements of photocatalytic property and practicability of Bi2WO6. Nanostructured Bi2WO6 materials are firstly introduced. The fabrication of Bi2WO6 nanostructures is found to be an effective strategy to enhance the photocatlytic activity for high surface areas. Then works on hierarchical Bi2WO6 superstructures are presented. In comparison with tiny Bi2WO6 nanostructures, the microscale superstructures are more practical for easy recovery. And channels or mesopores which are beneficial for ion transport often appear among nanostructured building units. Then the modification of Bi2WO6 photocatalyst is summarized which includes the composite heterostructures with metal oxides, surface deposition of metal or grapheme, and doping with metal ion or non-metal ion, etc. In addition, the immobilization techniques of Bi2WO6 materials are reviewed. Finally, the development trend of Bi2WO6 photocatalyts is prospected. It is emphasized that the band gap adjustment of Bi2WO6 and interfacial states of its heterostructures should be strengthened. And theoretical calculation would assist to in-depth understand the photocatalytic mechanism, which would be helpful in the improvement of existing photocatalysts and designing novel visible-light responsive photocatalyst. Contents
1 Introduction
2 Nanostructured Bi2WO6 photocatalyst
3 Hierarchical Bi2WO6 photocatalyst
3.1 Adjustment of medium acidity
3.2 Assistant of organic additive and template
3.3 Addition of inorganic salts
4 Heterostructured Bi2WO6 photocatalyst
4.1 Combination with metal oxide
4.2 Carbon modification
4.3 Metal deposition
5 Ion doping of Bi2WO6 photocatalyst
6 Immobilization of Bi2WO6 photocatalyst
7 Conclusion and prospect
Morphology-Controlled Synthesis of SnO2 as Lithium Ion Batteries Anode Materials
Wang Yali, Yu Jing, Li Rong, Zhen Qiang
2012, 24 (11): 2132-2142 |
Published: 24 November 2012
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Abstract
SnO2 is an important wide band-gap semiconductor material, which has broad application prospects as an anode material for lithium-ion battery due to its high theoretical capacity. In recent years, many studies have been carried out on the morphology-controlled synthesis of SnO2 because the micro-morphologies of the materials have an important impact on their physical and chemical properties. This paper reviewed morphology-controlled synthesis of SnO2 with various morphologies, such as particle, sheet, one-dimensional, hollow, hierarchical structures,etc. which is used as an anode material for lithium-ion battery, as well as the effects of their morphologies on their electrochemical performance. The effect of the various morphologies on their electrochemical properties and the development trend of the morphological control are also analyzed and summarized. Contents
1 Introduction
2 Lithium storage mechanism of SnO2
3 Controlled-synthesis of SnO2 with various morphologies and their electrochemical performance
3.1 SnO2 nanoparticles
3.2 SnO2 nanosheets
3.3 SnO2 one-dimensional nanostructures
3.4 SnO2 hollow nanostructures
3.5 SnO2 hierarchical structures
4 Conclusion and outlook
Fabrication, Formation Mechanisms and Potential Applications of Magnetic Metal Nanotubes
Li Xiangzi, Wei Xianwen
2012, 24 (11): 2143-2157 |
Published: 24 November 2012
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Abstract
Magnetic metal nanotubes (MMNTs) have novel hollow structures with inner and outer active surface and special properties of catalysis, magnetism and easier modification, which gradually become an important sort of one-dimension functional nanomaterials. MMNTs exhibit potential applications in the fields of molecular devices, magnetic materials, biomedicine, etc, and have drawn wide attention during last decade. In this paper, the main strategies for fabricating MMNTs via hard templates have been summarized, including electrodeposition, chemical deposition, template wetting, atomic layer deposition and hydrothermal processing technology. The special fabricating technologies for MMNTs based on hard-template, such as channels chemical modification, multistep template replication, high current, mercury cathode, precursor, sensitization, activation and other processing parameters, etc. are emphasized. Simultaneously, a formation mechanism for fabricating MMNTs via hard templates has been established, which contains three main aspects: substrates properties, nucleation environments and growth environments. The formation mechanisms of MMNTs under the different fabricating strategies, such as high-current-assisted-annular-substrate tubular growth, current-directed tubular growth, gas assistant tubular growth and so on, have been compared. Moreover, some other factors including the hydration layer, the mobilities of metal ions, the complexation of metal ions and current modes, also play important roles in the formation of nanotubes. Finally, the magnetic properties, the potential applications, and developing trends of MMNTs are discussed in brief. Contents
1 Introduction
2 Fabrication strategies of the magnetic metal nanotubes(MMNTs)
2.1 Hard-template-based technologies
2.2 Solution phase synthesize with soft template assistance
3 Formation mechanisms for fabrication MMNTs via hard templates
3.1 Substrates
3.2 Nucleation environments
3.3 Growth environments
4 Properties and potential applications of MMNTs
4.1 Magnetic properties
4.2 Biological applications
5 Outlooks
Application of Novel Carbon Nanomaterials to Electrochemistry
Feng Xiaomiao, Li Ruimei, Yang Xiaoyan, Hou Wenhua
2012, 24 (11): 2158-2166 |
Published: 24 November 2012
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Abstract
Recently, carbon nanomaterials have received great interest because of their unique mechanical, electrical, and chemical properties. Especially, some kinds of novel carbon materials including carbon nanofibers, carbon nanotubes, and graphene with large specific area, high conductivity, and good biocompatibility become research focus. These novel carbon nanomaterials have been applied in many fields due to their unique physical and chemical properties. Especially, carbon nanomaterials have shown their unique advantages in electrochemical field. This paper mainly review the application of carbon nanomaterials to electrochemistry including biosensor, supercapacitor, and fuel cell. Carbon nanomaterials have an important role in bioelectrochemical catalytic reaction due to that carbon nanomaterials have high specific area and excellent biocompatibility. Therefore, it can improve the electron transfer rate of enzyme. The biosensors based carbon nanomaterials have high sensitivity, broad linear range, and good stability and reproducibility. Carbon nanomaterial is the earlist and the best one in the supercapacitor electrode materials. The supercapacitor prepared by carbon nanomaterials has good cycle stability. The specific capacitance can be enhanced through the combination of carbon nanomaterials and pseudo-capacitors electrode materials. Carbon nanomaterials can act as the catalysts of fuel cell as well. It can improve the energy density, fuel utilization, and the ability to resist poisoning. Contents
1 Introduction
2 The application of carbon nanomaterials to electrochemical biosensor
2.1 The application of carbon nanotube and its composite to electrochemical biosensor
2.2 The application of carbon nanofiber to electrochemical biosensor
2.3 The application of graphene to electrochemical biosensor
3 The application of carbon nanomaterials to electrochemical supercapacitor
3.1 Supercapacitor of carbon nanomaterials
3.2 Supercapacitor of carbon nanocomposites
4 The application of carbon nanomaterials to fuel cell
5 Conclusion and outlook
Trivalent Actinides/Lanthanides Separation by Nitrogen Heterocyclic Ligands
Pan Dengfang, Ye Gang, Wang Fang, Chen Jing
2012, 24 (11): 2167-2176 |
Published: 24 November 2012
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Abstract
Trivalent actinides/lanthanides separation is one of key steps in partitioning and transmutation strategy, and is important for the advanced nuclear fuel cycle. However, the separation is a big challenge due to the similarities of physico-chemical properties between trivalent actinides and lanthanides. Solvent extraction has been widely studied and ligands containing soft donor atoms such as N, S have displayed good actinides selectivity over lanthanides. Nitrogen heterocyclic ligands have attracted much attention because of their relatively high separation factors and consistency with the “CHON principle” resulting in possibility of complete incineration. In this review, research progress on the typical nitrogen heterocyclic extractants in the last decade are covered, including Terpy, TPTZ, BTPs, BTBPs and TPEN series. The separation abilities and stabilities under various conditions are compared, and the extraction mechanism and impact factors of extraction ability are described. The design, optimization and prospect of the extractants are also proposed. Contents
1 Introduction
2 Nitrogen heterocyclic ligands used in trivalent actinides/lanthanides separation
2.1 Terpy and derivatives
2.2 TPTZ and derivatives
2.3 BTP and derivatives
2.4 BTBP and derivatives
2.5 Heterocycle-substituted aliphatic amines
2.6 Other nitrogen heterocyclic ligands
3 Summary and prospective development
Transition Metal-Catalyzed Trifluoromethylation Reaction of Aromatic Compounds
Qi Zisong, Dong Yali, Li Yaming, Duan Chunying
2012, 24 (11): 2177-2186 |
Published: 24 November 2012
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Abstract
Transition metal-catalyzed trifluoromethylation of aromatic compounds has been developed rapidly during the last decade. The substrate scope is expanding, new methods and novel trifluoromethyl reagents are continuing to emerge. Recent advances in transition metal-catalyzed trifluoromethylation of aromatic compounds are summarized in this paper. The reactions involve trifluoromethylation of aryl halides, arylboronic acids and C—H trifluoromethylation of arenes. In addition, the mechanisms of transition metal-catalyzed trifluoromethylation are discussed in details. Contents
1 Trifluoromethylation of aryl halides
1.1 Copper-mediated (catalyzed) trifluoromethyla-tion
1.2 Palladium and other metal-mediated (catalyzed) trifluoromethylation
2 Trifluoromethylation of arylboronic acids
2.1 CF3 SiR3 as trifluoromethyl reagents
2.2 Electrophilic trifluoromethyl reagents
2.3 Other trifluoromethyl reagents
3 C—H trifluoromethylation of aromatics
3.1 Direct C—H trifluoromethylation of aromatics
3.2 Indirect C—H trifluoromethylation of aromatics
4 Conclusion and outlook
Biological Applications of Zwitterionic Polymers
Liu Hongyan, Zhou Jian
2012, 24 (11): 2187-2197 |
Published: 24 November 2012
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Abstract
Zwitterionic polymers have hydrophilic anion and cation groups simultaneously, which make them highly hydrated and render them unique biological antifouling property, i.e., those polymers can resist nonspecific protein adsorption, bacterial adhesion, and biofilm formation. Such character makes them increasingly applied in a wide range of bio- and medical related fields recently. The widely accepted antifouling mechanisms, steric effects and hydration theory, are briefly introduced. Based on the biological antifouling character, zwitterionic polymers can be used in medical devices' antifouling coatings, antimicrobial coatings, anticoagulation coatings, biomedical diagnosis, drug delivery in vivo; gene delivery carriers, membrane separation and marine coatings. The article mainly reviews the progress of those applications. Finally, issues existed in these applications are also discussed and perspectives of these applications are put forward. Contents
1 Introduction
1.1 Steric repulsion theory
1.2 Hydration theory
2 Biological applications of zwitterionic polymers
2.1 Antifouling coating
2.2 Antimicrobial coating
2.3 Anticoagulation
2.4 Biomedical diagnosis
2.5 Drug delivery
2.6 Gene delivery
2.7 Others
3 Conclusion and perspective
Synthesis and Applications of Stimulus-Responsive Functional Polymers
You Shusen, Yang Wantai, Yin Meizhen
2012, 24 (11): 2198-2211 |
Published: 24 November 2012
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Abstract
Stimulus-responsive, or ‘smart’, polymers belong to the classes of functional polymers. There is a wide-range application of stimulus-responsive polymers in numerous areas such as drug controlled releasing, gene vectors, nanoparticles, nano-reactors, and it shows broad prospects. Therefore the smart polymers have attracted more and more interests during the last decade. Most of the stimulus-responsive polymers are amphiphilic polymers which are able to self-assemble to form series patterns of aggregates such as micelles and vesicles. When the aggregates are subjected to some external environmental stimuli it will produce the corresponding specific response. In particular the functional block responses specifically and as a result the structure phase transition and volume phase transition of the whole functional polymer will emerge. Stimulus-responsive polymers can be classified into several categories, depending upon the type of the external stimulus. Herein, we review some of the most interesting examples of recent advances and progressive application of the responsive polymers based on different stimuli, such as pH, temperature, light, molecular, electro-stimuli and chirality responsive polymers. The article summarizes the structural characteristics and synthetic methods. The mechanism of their functions and the relationship between the structure and properties are briefly discussed. The potential applications and the long-term prospect of these fields are introduced. Contents
1 Introduction
2 pH responsive polymers
3 Temperature responsive polymers
4 Light responsive polymers
5 Molecular responsive polymers
5.1 Solvent polarity responsive polymers
5.2 Glucose responsive polymers
5.3 Enzyme responsive polymers
6 Other responsive polymers
6.1 Electrostimuli-responsive polymers
6.2 Chirality responsive polymers
7 Conclusion and outlook
Adsorption of Heavy Metal Ions by Chitosan and Its Derivatives
Hu Huiyuan, Zhu Hong
2012, 24 (11): 2212-2223 |
Published: 24 November 2012
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Abstract
The structure of chitosan has abundent —NH2 and —OH, so it has good adsorption ability for heavy metal ions. As a kind of natural polymer, the adsorption properties of chitosan are affected by its physical form, the source of the raw materials, the degree of deacetylation and the pH value of the system. Therefore, to improve the adsorption properties and to expand its application range, it is an essential method to modify its physical and chemical properties of the natural chitosan. This paper reviews the progress in the modification methods of the chitosan and the adsorption behavior of its derivatives to the heavy metal ions. The future perspectives of the chitosan derivatives used in the treatment of heavy metal contaminated water is also discussed. Contents
1 Introduction
2 Physical modification of chitosan
3 Chemical modification of chitosan
3.1 Active groups modified chitosan
3.2 Crosslinked chitosan
3.3 Graft polymerization of chitosan
3.4 Molecular imprinted chitosan
3.5 Magnetic chitosan
3.6 Special modification method of chitosan
4 Chitosan composites
5 Adsorption mechanisms
5.1 Adsorption isotherms
5.2 Adsorption kinetics
5.3 Adsorption thermodynamics
6 Conclusion and outlook
Ion Sensor Based on Fluorous Liquid Phase Sensing Membrane with High Selectivity
Huang Meirong, Ding Yongbo, Shi Fengying, Li Xingui
2012, 24 (11): 2224-2233 |
Published: 24 November 2012
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Abstract
New fluorous liquid sensing membranes for the fabrication of potentiometric sensors are systematically summarized based on the latest literatures. Fluorous solvents, fluorophilic ion-exchangers and fluorophilic ionophores doped in the fluorous solvents, as well as inert fluorous porous supports, are reviewed thoroughly. The influence of the four factors on the performance of potentiometric sensors is concentrated. It is pointed out that both the fluorophilic ion-exchangers and ionophores used so far contain 2—8 perfluoroalkyl chains which are composed of 6—10 carbon atoms in each chain. Such a fluorous liquid phase sensing membrane possesses a superior lower detection limit compared with conventional poly(vinyl chloride)(PVC) membranes. For Ag(Ⅰ) potentiometric sensor based on the fluorous liquid membrane with solid contact through three-dimensionally ordered macroporous (3DOM) carbon, the lower detection limit can achieve 3.8×10-11 mol/L. Moreover, the potentiometric sensors based on the fluorous membranes demonstrate excellent selectivity. Logarithmic selectivity coefficient log Ki,Jpot of a blank fluorous membrane without ionophore spans a remarkably wide range of more than 16—18 orders of magnitude, which is 8 orders of magnitude wider than that of conventional PVC membrane without ionophore. The unique new potentiometric sensors based on fluorous liquid phase sensing membranes could play an important role in many areas such as environmental monitoring, food safety, especially in medical diagnosis and detection for biomaterials. Contents
1 Introduction
2 Fluorous liquid phase sensing membrane
2.1 Fluorous solvent
2.2 Fluorophilic ion-exchanger
2.3 Fluorophilic ionophore
3 Inert fluorous porous support membrane
4 Performance of fluorous membrane
4.1 Low detection limit
4.2 High selectivity
4.3 Strong ability of anti-contamination
5 Outlook
Quantum Dots-Based Drug Delivery System
Yang Huayan, Xiong Huanming, Yu Shaoning
2012, 24 (11): 2234-2246 |
Published: 24 November 2012
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Abstract
Fluorescent semiconductor quantum dots have shown great potential applications in analytical chemistry, biochemistry and biomedicine. The unique optical properties and various surface structures of QDs have received more and more intensive attention. Here,we present a review of current development in QDs, including their synthetic method, surface modification and bioconjugation, especially application in drug delivery. Contents
1 Introduction
2 Features and syntheses of QDs
2.1 Optical properties
2.2 Synthesis
2.3 Surface modification
2.4 Bioconjugation
3 Applications in drug delivery system
3.1 QDs as drug carries
3.2 QD-labeled drug carriers
4 Conclusion and outlook
DNA Biosensors Based on Functional Nanoprobes
Dong Haifeng, Zhang Xueji
2012, 24 (11): 2247-2254 |
Published: 24 November 2012
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Abstract
The accomplishment of the Human Genome Project and the progress in research of the functional genomics make gene diagnoses a hot spot in the areas of molecular biology and biomedicine. DNA biosensors, based on the bases pairing, can continuously, fast, sensitively detect the specific gene sequence, which have developed quickly in recent years. Nanoparticles are intensely studied in bioanalysis, owing to its unique physical and chemical properties, excellent biocompatibility, stable mechanical and facilitated modification properties. Various compositions, sizes, dimensions and shapes of nanomaterials such as quantum dot, noble metal nanoparticles, carbon nanomaterials are controllably tailored to couple different biomolecules in order to develop nanoprobes with desired properties for DNA biosensing. These biosensing devices can be employed for detection of DNA sequence with high sensitivity and selectivity. Contents
1 Introduction
2 The basic principle of DNA biosensors
3 General categories of DNA biosensors
4 The application of nanoparticles in DNA biosensors
4.1 Functional gold nanoprobe
4.2 Functional carbon nanoprobe
4.3 Functional semiconductor nanoprobe
5 Conclusion and outlook
HCV Non-Nucleoside NS5B Polymerase Inhibitors
Wu Daochun, He Yanping
2012, 24 (11): 2255-2267 |
Published: 24 November 2012
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Abstract
Hepatitis C virus (HCV) infection has emerged as a significant global public health problem, with an estimated 170 million chronically infected individuals worldwide, and a leading cause of liver transplantation. Currently neither a vaccine nor a therapy with effective broad spectrum mode of action against all genotypes of HCV is available. Current HCV therapy comprising of pegylated interferon α (PEGeIFN-α) in combination with ribavirin has found limited patient compliance due to severe adverse effects. In the past two decades, several approaches have been adopted to inhibit non-structural viral proteins. RNA dependent RNA polymerase coded by NS5B protein is an attractive therapeutic target, since it plays an important role in replicating the HCV RNA genome and the host lacks its functional equivalent. According to its function mechanism and chemical structure, NS5B inhibitors mainly divided into nucleoside inhibitors(NIs) and non-nucleoside inhibitors(NNIs), the latter can bind to less conserved sites outside the active site and impair the enzyme’s catalytic efficiency. Scince the benzimidazole-based compounds were identified as NS5B NNIs, several inhibitors targeting various known binding sites within HCV NS5B polymerase have demonstrated useful efficacy in clinical trials. In this article, the recent progress of NS5B NNIs, such as benzothiadiazines, benzimidazoles, indole analogs, thiophene carboxylic acids, isoquinoline and quinolones, dihydropyranones, diketo acids and so on, is reviewed to provide some useful information for the further research and development of HCV polymerase inhibitors. Contents
1 Introduction
1.1 Gene structure and replicative cycle of HCV
1.2 Structure of HCV NS5B polymerase and its relation ship of activity with RdRp
1.3 NS5B polymerase as an anti-HCV drug target
2 Non-nucleoside inhibitors of HCV NS5B polymerase
2.1 Benzothiadiazine analogs
2.2 Benzimidazole analogs
2.3 Indole analogs
2.4 Thiophene carboxylic acid analogs
2.5 Isoquinoline and quinolone analogs
2.6 Dihydropyranone analogs
2.7 Diketo acid analogs
2.8 The other non-nucleoside inhibitors
3 Conclusion
Latest Advances of Microbial Production of 2,3-Butanediol
Fu Jing, Wang Meng, Liu Weixi, Chen Tao
2012, 24 (11): 2268-2276 |
Published: 24 November 2012
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Abstract
As important liquid fuel and chemical raw materials, 2,3-butanediol and its derivatives have broad industrial application prospects. Economical and efficient 2,3-butanediol microbial production has significant impetus to the low-carbon and circular economy development of China. Focusing on the latest achievements in the microbial production of 2,3-butanediol, this review summarizes the hot spots of the researchers’ attentions nowadays, which can be divided into four parts: identification of the key genes and enzymes involved in the 2,3-butanediol metabolic pathway, development of new strains and metabolic engineered strains for high yield or chiral 2,3-butanediol production, strategies for fermentation optimization such as simultaneous saccharification and fermentation, and technology improvement for combining process involved in 2,3-butanediol recovering processing. These achievements in the last three years are classified and discussed with state-of-art views. At last, guidelines for future studies are also proposed. It is pointed out that future research should focus on new strains, new genes and enzymes, new metabolic pathways, new cheap and renewable resources for substrate, and new technology for fermentation and separation. There’s no doubt that metabolic engineered class Ⅰ strains, which can utilize cost-effective and renewable substrates to lower the raw materials cost producing chiral 2,3-butanediol with high yield and productivity, should be favored. Besides, new technology in separation and purification process must be developed and improved to lower the cost of downstream processing. Contents
1 Introduction
2 Identification of the key genes and enzymes involved in the metabolic pathway of 2,3-butanediol
2.1 Metabolic pathway analysis
2.2 Identification of the key genes and enzymes
3 Strains and their improvements
3.1 Major microorganisms producing 2,3-butanediol
3.2 Metabolic engineering of the microorganisms for high yield and productivity
3.3 Construction of the metabolic engineered microorganisms for single isomer production
4 Strategy of optimization for fermentation
4.1 Parameter optimization of culture environment
4.2 Economic fermentation substrates
4.3 Simultaneous saccharification and fermentation
4.4 Co-culture
5 Optimization of separation and purification process
6 Conclusion and outlook
Characteristics and Formation Mechanisms of Atmospheric Organosulfates
Ma Ye, Chen Jianmin, Wang Lin
2012, 24 (11): 2277-2286 |
Published: 24 November 2012
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Abstract
Atmospheric organosulfates refer to sulfate esters and their derivatives that have been identified in ambient secondary organic aerosol(SOA) samples. Recent laboratory and field studies show that organosulfates are derived from the reactions of particulate sulfates or sulfuric acid with compounds formed from hydroxyl radical(OH)/nitrate radical(NO3)/ozone(O3)-initiated reactions of isoprene, α-/β-pinene, and other monoterpenes and sesquiterpenes. Organosulfates can also be formed through reactive uptake of carbonyls such as glyoxal by particulate sulfates or sulfuric acid. Enhanced acidity of the sulfate seed particles favors the production of organosulfate. Hydrolysis of organosulfates is slow unless in a highly acidic solution. Offline electrospray ionization mass spectrometry(ESI-MS) and online aerosol mass spectrometry(AMS) are useful methods to detect atmospheric organosulfates. Contents
1 Introduction
2 Identification of atmospheric organosulfates
2.1 Organosulfates observed in the atmosphere
2.2 Temporal profiles of organosulfates
3 Laboratory studies of organosulfates
3.1 Organosulfates derived from isoprene
3.2 Organosulfates derived from α-/β-pinene
3.3 Organosulfates derived from other monoterpenes and sesquiterpenes
3.4 Organosulfates formation via reactive uptake of carbonyls
3.5 Hydrolysis of organosulfates and organonitrates
4 Analytical methods of organosulfates
5 Outlook