放射性废物水泥固化的理论基础,研究现状及对水泥化学研究的思考

水泥具有优良的物理、化学及力学性能，是固化放射性废物的良好基体材料，本文概要介绍水泥作为固化材料的科学理论依据，以及固化处理方面的研究应用现状，并对水泥化学学科的发展提出初浅的认识。     

Recent Progress in Biocatalysis with Enzymes Immobilized on Mesoporous Hosts

Enzymes are highly desirable in green and sustainable chemistry. One of the major issues in biocatalysis is enzyme stabilization under in vitro process conditions and catalyst recycling. In recent years, mesoporous materials have been extensively explored as supports for immobilization of enzymes. This review describes the recent developments in enzyme immobilization in mesoporous materials and their potential applications as biocatalysts in the chemical and pharmaceutical industry.     

Die Bedeutung der Biotechnologie für die industrielle Chemie

The significance of biotechnology for industrial chemistry. In the next few decades biotechnology will bring about fundamental innovations in the fields of health, nutrition, and agriculture as well as in important branches of industrial production, such as chemistry, which may well be comparable in importance with the present revolutionary technical progress based on electronics. Justification for these forecasts comes mainly from pioneering scientific advances in the fields of molecular biology, biochemistry, and microbiology. Particular mention should be made here of the fascinating potential of genetic engineering methods presently undergoing rapid development. However, less spectacular techniques, such as cell fusion and the immobilization of enzymes or whole living cells on polymeric substrates to give manageable, long-lived biocatalysts, will also contribute to this wave of innovation. Some of these new developments are now gaining acceptance in industrial production.     

Flow Chemistry – A Key Enabling Technology for (Multistep) Organic Synthesis

Laboratory scaled flow‐through processes have seen an explosive development over the past decade and have become an enabling technology for improving synthetic efficiency through automation and process optimization. Practically, flow devices are a crucial link between bench chemists and process engineers. The present review focuses on two unique aspects of modern flow chemistry where substantial advantages over the corresponding batch processes have become evident. Flow chemistry being one out of several enabling technologies can ideally be combined with other enabling technologies such as energy input. This may be achieved in form of heat to create supercritical conditions. Here, indirect methods such as microwave irradiation and inductive heating have seen widespread applications. Also radiation can efficiently be used to carry out photochemical reactions in a highly practical and scalable manner. A second unique aspect of flow chemistry compared to batch chemistry is associated with the option to carry out multistep synthesis by designing a flow set‐up composed of several flow reactors. Besides their role as chemical reactors these can act as elements for purification or solvent switch.     

Site‐Specific Immobilization of the Peptidoglycan Synthase PBP1B on a Surface Plasmon Resonance Chip Surface

Surface plasmon resonance (SPR) is one of the most powerful label‐free methods to determine the kinetic parameters of molecular interactions in real time and in a highly sensitive way. Penicillin‐binding proteins (PBPs) are peptidoglycan synthesis enzymes present in most bacteria. Established protocols to analyze interactions of PBPs by SPR involve immobilization to an ampicillin‐coated chip surface (a β‐lactam antibiotic mimicking its substrate), thereby forming a covalent complex with the PBPs transpeptidase (TP) active site. However, PBP interactions measured with a substrate‐bound TP domain potentially affect interactions near the TPase active site. Furthermore, in vivo PBPs are anchored in the inner membrane by an N‐terminal transmembrane helix, and hence immobilization at the C‐terminal TPase domain gives an orientation contrary to the in vivo situation. We designed a new procedure: immobilization of PBP by copper‐free click chemistry at an azide incorporated in the N terminus. In a proof‐of‐principle study, we immobilized Escherichia coli PBP1B on an SPR chip surface and used this for the analysis of the well‐characterized interaction of PBP1B with LpoB. The site‐specific incorporation of the azide affords control over protein orientation, thereby resulting in a homogeneous immobilization on the chip surface. This method can be used to study topology‐dependent interactions of any (membrane) protein.     

生物功能催化膜定点固定化技术研究进展

介绍了从生物物理学、生物分析化学、化学工程学和分子生物学等学科角度研究开发的基于定点固定化技术的生物功能催化膜。着重阐述了基因定点突变技术、基因融合技术和翻译修饰技术等新兴定点固定化技术的原理、特点和操作。最后,对生物功能催化膜的研究方向进行了展望。     

Chemically-Specific Probes for the Atomic Force Microscope

The atomic force microscope (AFM) measures force and displacement with high sensitivity and submillisecond temporal resolution. By functionalizing the AFM probe with specific chemical groups or macromolecules it is possible to characterize the chemical and physical properties of single molecules on the nanometer scale. In this paper we discuss the key issues that must be addressed when designing and characterizing a successful immobilization chemistry, and describe the chemistry we developed to covalently immobilize oligonucleotides in a specific orientation.     

A photochemical method for immobilization of azidated dextran onto aminated poly(ethylene terephthalate) surfaces

BACKGROUND: Dextran, a bacterial polysaccharide, has been reported to be as good as poly(ethylene glycol) in its protein‐rejecting and cell‐repelling abilities. In addition, the multivalent nature of dextran is advantageous for surface grafting of biologically active molecules. We report here a method to photochemically bind dextran hydrogel films to aminated poly(ethylene terephthalate) (PET) surfaces in aqueous media using a heterobifunctional crosslinker, 4‐azidobenzoic acid. In order to achieve this, dextran was first functionalized with the crosslinker using carbodiimide chemistry followed by photo‐crosslinking and immobilization onto the nucleophile‐rich aminated PET surfaces. RESULTS: The presence of the immobilized dextran on PET was verified by attenuated total‐reflection Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy and contact angle measurements. The grafted surface was highly hydrophilic due to the heavily hydrated polysaccharide network on the surface as demonstrated by the near zero water contact angle. CONCLUSION: A photochemical method for surface immobilization of dextran onto aminated PET using aryl azide chemistry is a facile technique to generate highly hydrophilic and more hemocompatible surfaces. The aryl nitrenes generated by photolysis produce a metastable, electron‐deficient intermediate, azacycloheptatetraene, which is believed to be responsible for the simultaneous crosslinking of dextran and its immobilization onto the aminated PET surface. The aryl azide chemistry reported here for dextran could be useful as a versatile technique for surface modification of other nucleophile‐rich polymers to create dextran‐ or similar polysaccharide‐immobilized surfaces. Copyright © 2007 Society of Chemical Industry     

粮食发酵制醋酸技术的研究进展

介绍了国内外粮食发酵制醋酸技术的研究进展，包括固定化细胞发酵技术，膜技术等，随着绿化学和生物工程技术的发展，该技术将会引起更多的关注。     

Hybrid graphite film–carbon nanotube platform for enzyme immobilization and protection

A novel platform consisting of a multilayered substrate, activated graphite-like carbon film, and dense forest of long, vertically-aligned multiwall carbon nanotubes grown by the chemical vapor deposition is designed, fabricated, and tested for covalent immobilization of enzymatic biocatalysts with the aim of protecting them from shear forces and microbial attacks present in bioreactors. The covalent bonding ensures enzyme retention in a flow, while the dense nanotube forest may serve as a protection of the enzymes from microbial attack without impeding the flow of reactants and products. This platform was demonstrated for the two reference enzymes, horseradish peroxidase and catalase, which were immobilized without degrading their biological activity. This combination of an activated carbon layer for an efficient immobilization of biocatalysts with a protective layer of inert carbon nanotubes could dramatically improve the efficiency and longevity of enzymatic bio-catalysis employed in a large variety of advanced biotechnological processes.     

Immobilization of Proteins in their Physiological Active State at Functionalized Thiol Monolayers on ATR‐Germanium Crystals

Protein immobilization on solid surfaces has become a powerful tool for the investigation of protein function. Physiologically relevant molecular reaction mechanisms and interactions of proteins can be revealed with excellent signal‐to‐noise ratio by vibrational spectroscopy (ATR‐FTIR) on germanium crystals. Protein immobilization by thiol chemistry is well‐established on gold surfaces, for example, for surface plasmon resonance. Here, we combine features of both approaches: a germanium surface functionalized with different thiols to allow specific immobilization of various histidine‐tagged proteins with over 99 % specific binding. In addition to FTIR, the surfaces were characterized by XPS and fluorescence microscopy. Secondary‐structure analysis and stimulus‐induced difference spectroscopy confirmed protein activity at the atomic level, for example, physiological cation channel formation of Channelrhodopsin 2.     

Reticular Chemistry of Multifunctional Metal-Organic Framework Materials

Metal-organic frameworks (MOFs) are crystalline solids constructed by means of reticular chemistry (refers to the connection of molecular building units via strong bonds to make extended structures), which is currently one of the most rapidly expanding platforms for new functional materials. Rational combinations of various building units enable MOFs to show tailorable pore structures. Based on well-established approaches, including the control over pore size and pore chemistry, immobilization of functional sites, post-synthetic modification, and multivariate complex, multifunctional MOFs can be readily synthesized. In this brief review, we summarize and highlight our research progress in MOF chemistry on applications including gas storage, gas separations, optical response, chemical sensing, proton conduction, and molecular recognitions.     

Au/PANA/PVAc and Au/P(ANA-co-CNTA)/PVAc electrospun nanofibers as tyrosinase immobilization supports

Au/poly anthranilic acid/poly vinyl acetate and Au/poly(anthranilic acid-co-3-carboxy-N-(2-thenylidene)aniline)/poly vinyl acetate nanofibers through electrospinning and their modification with covalent tyrosinase (Ty) immobilization was performed. It was realized by surface activation using N-(3-dimetylaminopropyl)-N-ethylcarbodimide hydrochloride/N-hydroxysuccinimide chemistry. Electrochemical impedance spectroscopy (EIS), FTIR–ATR, Raman spectroscopy, and bicinchoninic acid assay analyses demonstrated that Ty was stably and covalently bonded onto the nanofibers. Increase in surface roughness [atomic force microscopy (AFM)] and the presence of Cu atoms in the nanofiber composition after enzyme immobilization confirmed the Ty immobilization. The charge transfer resistances of the nanofibers decreased due to changes in the nanofiber surfaces after attachment of enzyme.     

Fabrication of hydrophilic nanoporous PMMA/O-MMT composite microfibrous membrane and its use in enzyme immobilization

The electrospun PMMA/O-MMT microfibrous membranes were pretreated by oxygen plasma to create substrates with better adsorption capability. The amount of O-MMT and conditions of plasma treatment were optimized for maximum laccase immobilization on these pretreated surfaces of the microfibrous membranes. The surface morphology and chemistry of the composite microfibrous membranes after plasma treatment and laccase immobilization were investigated by SEM and FTIR. The immobilized laccase showed better resistance to pH and temperature changes than that of the free form laccase, and after 10 successive runs of repeated use, the immobilized laccase still retained 30 % of its initial activity. Reactive X-3B was successfully degraded by both free and immobilized laccase.     

无机材料在酶固定化中的应用

综述了近年来无机材料在国内外酶固定化研究中的应用,着重介绍了载体材料的表面处理方法及相应的酶固定化方法,并对无机材料在酶固定化中的应用作了展望。     

聚芳醚酮的表面修饰及其在生物医用领域的应用

综述了特种工程塑料聚芳醚酮的表面修饰方法及其在生物医用领域的应用。重点介绍了选择性湿化学法和等离子体处理等聚芳醚酮表面改性方法及通过固定细胞外基质的生物功能化途径;最后,介绍了聚芳醚酮及改性聚芳醚酮在细胞培养基体、椎间融合器、关节摩擦面等临床植入体方面的应用进展,并对聚芳醚酮在生物医用领域的发展前景进行了展望。     

Sensitizer immobilization in photochemistry: evaluation of a novel green support

BACKGROUND: Green chemistry, also known as sustainable chemistry, refers to environmentally friendly chemicals and processes that result in reduced waste, elimination of costly end‐of‐the‐pipe treatments; safer products, and reduced use of energy and resources. In this context this study aims to evaluate a novel green sensitizer support for photochemistry use. For this propose, Rose Bengal (RB) and juglone production were chosen as a model sensitizer and a model photoreaction, respectively. RESULTS: The results showed that the RB‐alginate beads prepared using a solution of 20% CaCl₂ had better stability in the solvent t‐amyl alcohol. Comparing all the immobilized systems a larger reaction yield (57.5%) was obtained when the proportion of the beads in the photoreactor flask was 5% (v/v). Although when using suspended RB the reaction yield was better (62%) the environmental friendly attributes and economical advantages of immobilized systems overcome it. CONCLUSIONS: The potentiality of this new kind of sensitizer immobilization was demonstrated and a mechanism based on immobilization of cells was proposed. Furthermore the use of this novel green support presents a greater efficiency and potentially lower costs than the commercial supported RB Sensitox. Copyright © 2009 Society of Chemical Industry     

后台阶反应流概率密度函数-雷诺应力法模拟

后台阶流动是计算流体力学领域十分重要的课题,但是后台阶流动与化学反应耦合的数值研究则比较少见.文中使用雷诺应力模型模拟后台阶流动的速度场,使用标量联合概率密度函数(PDF)方程模拟化学反应项,并将化学反应项的结果作为源项引入雷诺应力模型,模拟了后台阶流动中的甲烷与氧气的缓慢氧化反应.结果发现:雷诺应力模型能够很好地模拟...     

Potential of Different Enzyme Immobilization Strategies to Improve Enzyme Performance

Enzyme biocatalysis plays a very relevant role in the development of many chemical industries, e.g., energy, food or fine chemistry. To achieve this goal, enzyme immobilization is a usual pre‐requisite as a solution to get reusable biocatalysts and thus decrease the price of this relatively expensive compound. However, a proper immobilization technique may permit far more than to get a reusable enzyme; it may be used to improve enzyme performance by improving some enzyme limitations: enzyme purity, stability (including the possibility of enzyme reactivation), activity, specificity, selectivity, or inhibitions. Among the diverse immobilization techniques, the use of pre‐existing supports to immobilize enzymes (via covalent or physical coupling) and the immobilization without supports [enzyme crosslinked aggregates (CLEAs) or crystals (CLECs)] are the most used or promising ones. This paper intends to give the advantages and disadvantages of the different existing immobilization strategies to solve the different aforementioned enzyme limitations. Moreover, the use of nanoparticles as immobilization supports is achieving an increasing importance, as the nanoparticles versatility increases and becomes more accessible to the researchers. We will also discuss here some of the advantages and drawbacks of these non porous supports compared to conventional porous supports. Although there are no universal optimal solutions for all cases, we will try to give some advice to select the optimal strategy for each particular enzyme and process, considering the enzyme properties, nature of the process and of the substrate. In some occasions the selection will be compulsory, for example due to the nature of the substrate. In other cases the optimal biocatalyst may depend on the company requirements (e.g., volumetric activity, enzyme stability, etc).     

The Development of Visible-Light Photoredox Catalysis in Flow

Visible-light photoredox catalysis has recently emerged as a viable alternative for radical reactions otherwise carried out with tin and boron reagents. It has been recognized that by merging photoredox catalysis with flow chemistry, slow reaction times, lower yields, and safety concerns may be obviated. While flow reactors have been successfully applied to reactions carried out with UV light, only recent developments have demonstrated the same potential of flow reactors for the improvement of visible-light-mediated reactions. This review examines the initial and continuing development of visible-light-mediated photoredox flow chemistry by exemplifying the benefits of flow chemistry compared with conventional batch techniques.