Immobilization of penicillin acylase on copolymer of butyl acrylate and ethylene glycol dimethacrylate

The effects of glutaraldehyde, enzyme concentrations and reactants volumes, ionic strength, pH value and carrier particle diameter on immobilization of penicillin acylase onto acrylic carriers were studied. The activity of immobilized enzyme preparations was also studied over a range of pH values and temperatures and thermal and pH stabilities were determined. The use of the immobilized preparation for penicillin G hydrolysis in a batch reactor was investigated. The immobilized enzyme gave a significant reduction in hydrolysis time compared to hydrolysis by the native enzyme.     

烯烃聚合后过渡金属催化剂负载化研究进展

综述了后过渡金属催化剂负载化方式和载体的种类及其催化特性,该催化剂载体包括无机载体、聚合物载体、自固载和介孔分子筛等。通过与均相催化剂性能的比较,进一步阐述了负载的目的和必要性。随着这一领域研究深入,将对后过渡金属催化剂工业化发展具有重要的意义。     

New supports for enzyme immobilization based on copolymers of vinylene carbonate and β‐hydroxyethylene acrylate

Vinylene carbonate (VCA), β‐hydroxyethylene acrylate, and N,N′‐methylene bisacrylamide were dissolved in water, and the aqueous solutions were copolymerized via reverse‐phase suspension copolymerization in paraffin oil. A series of hydrophilic and beaded supports containing reactive cyclic carbonate groups for enzyme immobilization were obtained. The supports were examined by coupling with trypsin, and the results showed that the amount of enzymes coupled to the supports and the specific activity of the immobilized trypsin were related to the content of VCA structure units and the reaction time. Meanwhile, the optimal pH and temperature, as well as the Michaelis–Menten constant K_m, for both native and immobilized trypsin were measured. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 94–102, 2002     

Immobilization of hybridoma cells in chitosan alginate beads

A new method for immobilizing hybridoma cells using chitosan-stabilized calcium alginate beads was developed. The ionotropic gelation of chitosan and calcium with alginate resulted in the formation of highly cross-linked, porous beads that were mechanically and chemically stable in phosphate buffered medium. Hybridomas entrapped in these beads were cultured semi-continuously using periodic medium exchange. Viable population densities in the order of 5 × I0⁷ cells/mL were attained within the beads and up to two-fold increases in volumetric monoclonal antibody (MAb) productivity over batch suspension cultures were observed. Oxygen mass transfer limitations within the chitosan-alginate beads were evaluated by considering biokinetics and diffusive transport. Model equations were developed and used to evaluate the effect of bead diameter on the contained cells. The predictions were consistent with experimental observations of maximum viable population densities attained in beads of various size.     

A new route for the preparation of cyano‐containing poly(N‐isopropylacrylamide) microgel latex for specific immobilization of antibodies

A prepolymerization process was used to prepare functionalized poly(N‐isopropylacrylamide) latexes with surface cyano groups. The functionalized latexes prepared were characterized by FTIR, ¹H NMR, scanning electron microscopy and quasi‐elastic light scattering. In addition, the polymerization conversion and the water‐soluble polymer amounts were quantified. The polymerization conversions were found to be above 80% with 5–14 wt% of water soluble polymer formation. The immobilization of antibody (immunoglobulin) onto such cyano‐containing thermally sensitive particles, suggests the feasibility of specific dipole–dipole interactions between the cyano and hydroxyl functional groups from particle and antibody, respectively. Copyright © 2004 Society of Chemical Industry     

Design considerations for an immobilized cell bioreactor operating in a batch recirculation mode

Immobilizing microbial cells and enzymes used in biological and biochemical processes is advantageous and has been a subject of intensive study in recent years. Successful implementation of this technology requires complete understanding of physical, chemical and biological parameters which influence the performance of such a system. This paper focuses on a few basic design considerations which are essential to the design and operation of immobilized cell bioreactors. A process using microorganisms entrapped in calcium alginate gel as a biocatalyst is considered. This system is used to biodegrade the organic compound, phenol. A batch reactor operated in a recirculation mode is used, and parameters like concentration of dissolved oxygen, concentration of the organic compound, bead size, biomass loading and the flow rate are studied. The bioreactor can be operated within many operating windows where one of the above parameters may be rate limiting. With the help of conceptual and experimental data, the influence of the above parameters on the reaction rates is discussed.     

Study on Immobilized Algal Cells for Treatment and Recycle of Refinery Wastewater

Compared to the algal oxidation pond,treatment of wastewater using the immobilized algal celltechnology has excellent effect,which not only can effectively avoid the disadvantage of oxidation pond,but can also remarkably improve the efficiency of treating system and the effluent quality.When thetreating system operates under an optimal control conditions,such as a 55% loading rate,an illuminationintensity of 2500—3500 lux and a hydraulic residence time of 4 hours,the COD and ammonia nitrogenremoval can reach 90%.Water after deep treatment can comply with the requirement of the refinery for thequality of recycled water.     

一种以高分子PEI为载体的辅酶NADH模型物的合成研究

在已有的研究基础上,发展了一种以水溶性高分子聚乙烯亚胺(PEI)为载体,以1-苄基-3-羧基吡啶为辅酶NADH模型物的新型的具有良好水溶性的高分子辅酶NADH模型物的合成方法。     

镧系元素模拟衰变子体对An_2Zr_2O_7固化体结构及其γ辐照性能的影响

锆基烧绿石An2Zr2O7以优异的抗辐照性能和化学稳定性成为高放废物中锕系核素的理想固化基材,高放废物固化体在长期贮存过程中不断衰变产生衰变子体,必将影响固化体的结构和性能。本文以镧系核素Nd模拟锕系核素Pu、Am,La模拟其衰变子体U、Np,通过溶胶凝胶方法合成了(LaxNd1-x)2Zr2O7模拟固化体。样品经高能γ辐照,辐照剂量为233.78kGy。利用X射线衍射、Raman振动光谱和结构精修方法对辐照前后的系列样品进行了分析。结果表明:(LaxNd1-x)2Zr2O7系列固化体均为单一的烧绿石结构相;固化体的晶格常数随La的增加呈线性增加,晶体结构趋于有序化,意味着衰变子体有助于固化体趋向于更加有序的烧绿石结构。γ辐照和结构精修结果表明,随着子体的增加,An—O48f键长增大,离子键结合力减小,在辐照情况下晶格易发生无序化,抗辐照能力减弱。     

Development of a compact high-density microbial hydrogen reactor for portable bio-fuel cell system

The development of a compact high-density microbial reactor for hydrogen production is described with possible implications to use as a portable bio-fuel cell system. To construct the compact bioreactor, mainly, the cell density and immobilization methods were optimized in this paper. The encapsulation of hydrogen producing bacterium, Escherichia coli strain MC13-4, in alginate gel beads provided approximately three-fold increase in hydrogen production in comparison with the free cell suspension. The immobilized cells (cell density; O.D. 100) and 500 mM glucose solution were packed into a 20 mL glass bottle that was connected to the fuel cell. This system has generated electricity of over 20 mW for 20 min.