溶胶-凝胶法固定脂肪酶的方法研究

采用溶胶-凝胶技术,以正硅酸乙酯为前驱物,制备了S iO2微粒,以3-氨基丙基三乙氧基硅烷作偶联剂对S iO2微粒进行表面改性,制备了一种功能化载体3-氨基丙基硅胶。以甲醛为偶联剂,将脂肪酶固定于3-氨基丙基硅胶上。用红外光谱对产物结构进行表征,同时研究了固定化酶的性质。结果表明,氨基化硅胶交联固定化脂肪酶具有可行性,固定化酶的最适反应温度在30℃附近,且在碱性范围内其稳定性比自然酶高;当pH=7.5,其它条件相同时,自然酶的活力大于固定化酶的活力。     

溶胶-凝胶法制备载体硅胶研究进展

溶胶-凝胶法包括一次溶胶-凝胶和反复溶胶-凝胶两种工艺。一次溶胶-凝胶工艺主要有两种,一是以碱性溶液为底液,并流方式加入无机酸和硅酸盐,或是以单股流的方式加入无机酸;二是以酸性溶液为底液,采用单股流的方式加入硅酸盐。这种制备工艺的特点在于能够获得大孔径、高比表面积的硅胶,然而对于孔分布及孔结构的调整受限。反复溶胶-凝胶工艺主要是以酸性溶液为底液,过程中加入碱性介质及有机醇溶剂,同时配合水热反应。这种制备工艺能够准确控制载体硅胶的孔结构及孔分布,并能大幅提升硅胶的比表面积,从而提高催化剂活性。     

固定化Br(ō)nsted酸性离子液体催化酯化反应

设计合成了1-甲基-3-丁烷磺酸咪唑硫酸氢盐([( n -Bu-SO3H)MIm][HSO4])、1-甲基-3-丁烷磺酸咪唑对甲苯磺酸盐([( n -Bu-SO3H)MIm][ p -CH3C6H4SO3])和硫酸三乙胺([Et3NH][HSO4])3种Brōnsted酸性离子液体,考察了其催化正己酸与乙醇酯化反应的活性,分别采用浸渍法和溶胶-凝胶法将活性最佳的离子液体[( n -Bu-SO3H)MIm][HSO4]固定在硅胶上,对固定化离子液体催化正己酸与乙醇酯化反应的性能及重复使用性能进行了比较,并采用 1H NMR、元素分析和FTIR等方法对其进行了表征.研究结果表明:采用浸渍法A、浸渍法B和溶胶-凝胶法固定的离子液体的负载量(质量分数)分别为15.5 %、20.5 %和40.5 %,催化正己酸与乙醇酯化反应所得正己酸乙酯的产率分别为75.3%、92.6%和92.6%.但浸渍法制备的固定化离子液体不稳定,重复使用4次(浸渍法A)和8次(浸渍法B)后离子液体负载量分别下降到3.0 %和7.0 %,正己酸乙酯产率分别降为24.2%和64.5%;而采用溶胶-凝胶法制备的固定化离子液体重复使用10次后,离子液体的负载量为39.0%,流失很少,正己酸乙酯产率依然高达92.7%.将溶胶-凝胶法制备的固定化离子液体进一步应用于其他脂肪酸与乙醇的酯化反应,乙酯产率均在90.0%左右,表明采用溶胶-凝胶法是制备固定化离子液体催化剂的有效方法.     

包埋生物分子的SiO2载体材料的研究进展

综述了用于包埋生物分子生物传感器的溶胶-凝胶的制备过程,影响包埋的生物分子活性的因素、生物分子在载体中的性质以及载体的改性.重点阐述了对载体的改进,主要是对无机二氧化硅载体材料的有机掺杂.展望了新的生物兼容的溶胶-凝胶载体的设计.     

有机相中壳聚糖-海藻酸固定化脂酶的特性

研究了壳聚糖 海藻酸固定化脂酶在有机相反应中的稳定性与活性。考察了凝胶时间、壳聚糖浓度及壳聚糖分子质量对固定化脂酶包埋率与活性的影响 ,确定了适宜 pH值与批反应时间。同时讨论了溶剂极性和操作时间对固定化酶稳定性的影响。测定了固定化脂酶水解橄榄油反应的动力学参数。结果表明 ,壳聚糖 海藻酸聚电解质膜可提高固定化酶的包埋率与稳定性     

不同制备工艺对催化剂载体硅胶的性能影响

溶胶-凝胶法是制备载体硅胶的主要工艺,考察一次溶胶-凝胶与多次溶胶-凝胶工艺对载体硅胶表面形态、孔结构、以及所负载催化剂性能的影响。实验结果表明:采用多次溶胶-凝胶工艺可获得多峰孔分布的孔结构,所负载的催化剂活性高,获得聚合物粒子形态好。     

固定化Bronsted酸性离子液体催化酯化反应

设计合成了1-甲基-3-丁烷磺酸咪唑硫酸氢盐（［（n-Bu-SO₃H）MIm］［HSO₄］）、1-甲基-3-丁烷磺酸咪唑对甲苯磺酸盐（［（n-Bu-SO₃H）MIm］［p-CH₃C₆H₄SO₃］）和硫酸三乙胺（［Et₃NH］［HSO₄］）3种Bronsted酸性离子液体,考察了其催化正己酸与乙醇酯化反应的活性,分别采用浸渍法和溶胶-凝胶法将活性最佳的离子液体［（n-Bu-SO₃H）MIm］［HSO₄］固定在硅胶上,对固定化离子液体催化正己酸与乙醇酯化反应的性能及重复使用性能进行了比较,并采用¹H NMR、元素分析和FTIR等方法对其进行了表征。研究结果表明：采用浸渍法A、浸渍法B和溶胶-凝胶法固定的离子液体的负载量（质量分数）分别为15.5 %、20.5 %和40.5 %,催化正己酸与乙醇酯化反应所得正己酸乙酯的产率分别为75.3%、92.6%和92.6%。但浸渍法制备的固定化离子液体不稳定,重复使用4次（浸渍法A）和8次（浸渍法B）后离子液体负载量分别下降到3.0 %和7.0 %,正己酸乙酯产率分别降为24.2%和64.5%;而采用溶胶-凝胶法制备的固定化离子液体重复使用10次后,离子液体的负载量为39.0%,流失很少,正己酸乙酯产率依然高达92.7%。将溶胶-凝胶法制备的固定化离子液体进一步应用于其他脂肪酸与乙醇的酯化反应,乙酯产率均在90.0%左右,表明采用溶胶-凝胶法是制备固定化离子液体催化剂的有效方法。     

溶胶-凝胶自蔓法制备纳米材料的研究进展

综述了溶胶-凝胶自蔓法制备纳米材料的机理、过程及其应用。研究表明，由硝酸盐和有机燃料形成的干凝胶，具有自蔓延燃烧的特性。将溶胶-凝胶和自蔓延燃烧法相结合，开发了溶胶-凝胶自蔓法制备纳米材料的新技术。     

辣根过氧化物酶固定化方法的探索及分析应用

1前言固定化酶是20世纪60年代开始发展起来的一项新技术，是酶工程的主要内容，它的发展很快。近年来人们已开始转向固定化酶在工业、医学、化学分析、环境保护、能源开发等方面的应用研究。目前，国际上采用的酶的固定化方法包括：吸附法、健合法、包埋法和交税法等。吸附法制备的固定化酶会导致酶的较大程度的失活。为了克服酶的流失、渗漏，提高酶的活性收率，本实验设计出了两种新的固定化方法：氧化铝吸附一海藻酸钠包埋法及氧化铝吸附-戊二醇交联一海藻酸钠包埋法，以辣报过氧化物酶（HRP）制备固定化酶，并应用于混样中L－Tyr和雨…     

溶胶-凝胶法制备有机-无机杂化纳米级功能材料

概要总结了溶胶-凝胶法制备有机-无机杂化功能材料的一些制备方法,说明了溶胶-凝胶法中存在的问题,并介绍了解决这些问题的研究.     

硅胶固载咪唑离子液体的制备及二氧化碳吸附性能

分别采用浸渍法和溶胶-凝胶法将1-丁基-3-甲基咪唑四氟硼酸离子液体固载在A型和B型硅胶上,并对硅胶固载离子液体样品进行了FTIR、SEM、元素分析和CO2吸附表征。研究了负载方法、离子液体负载量、孔径分布等对CO2吸附性能的影响。结果表明:采用溶胶-凝胶法固载的离子液体负载量远远大于浸渍法的;制备的吸附剂均具有发达的微孔结构,且在0.4～0.8 nm有连续的分布;浸渍法制备的硅胶固载离子液体的CO2吸附性能较优,在273 K、0.1 MPa时,A型硅胶浸渍离子液体和乙醇混合液样品的CO2吸附量达1.92%。     

Immobilization of enzymes to porous-bead polymers and silica gels activated by graft polymerization of 2,3-epoxypropyl methacrylate

Three types of organic polymers and bead-shape silica gels were activated by graft polymerization of 2,3-epoxypropyl methacrylate; in some cases, epoxide groups on the support surface were modified to NH₂ groups. Eight active matrices so obtained were assessed as supports for immobilized enzymes using peroxidase, glucoamylase and urease. The immobilization yield of protein and specific activities of enzymes were better with supports containing NH₂ groups than with those containing epoxide spacer arms. Maximum enzyme immobilization and storage stabilities were obtained with silica-gel beads activated by graft polymerization of 2,3-epoxypropyl methacrylate. With all eight matrices tested, the immobilized enzymes showed good stability with not less than 82% of the original activity persisting after 28 days. The developed matrices have potential for use in process-scale biotechnological operations.     

温度对温敏性固定化酶的相对活力影响研究

以N 异丙基丙烯酰胺 (PNIPAM)均聚凝胶和N 异丙基丙烯酰胺与丙烯酰胺 [P(NIPAM -AM) ]共聚凝胶为载体制备了四种温敏性固定化酶。其相对活力 (f)随温度的升高而降低 ,在凝胶低临界溶解温度LCST(32 0℃ )附近骤降 (均聚枯草杆菌蛋白酶的f在 32 0℃前后由 86 2 %降至 18 8% ) ,即高温下 (LCST以上 )酶从凝胶中释放出来 ,说明温敏性凝胶可用作生物固定化催化剂的功能性载体。     

Preparation of silica/poloxamer composite by sol-gel process and pore control of silica gel obtained from the composite

Silica gels that controlled the pore size were prepared by calcination of silica/organic polymer (50/50 wt %) composites prepared by the sol-gel process. Poly(ethylene oxide) (PEO)-poly(propyrene oxide) (PPO)-PEO triblock copolymers, which are called poloxamers, were used as an organic polymer. The pore control of the silica gels was carried out by changing the molecular weight of PEO or PPO in the poloxamers. The silica gels obtained by the above procedure had a dual pore size of around 4 nm and below 2 nm in diameter, and the specific surface area was 500–1000 m²/g. The poloxamer molecules were supposed to be dispersed monomolecularly in the composites. Therefore, the pore structure of the silica gels reflected the structure of the poloxamer and, particularly, the radius of gyration of PPO in the composites. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 763–768, 1997     

Synthesis of geranyl acetate by esterification with lipase entrapped in hybrid sol-gel formed within nonwoven fabric

Candida cylindracea lipase was entrapped in organic-inorganic hybrid sol-gel polymers made from tetramethoxysilane (TMOS) and alkyltrimethoxysilanes. By forming the gels within the pores of a nonwoven polyester fabric, a novel immobilized biocatalyst in sheet configuration based on sol-gel en-trapment of the enzyme was obtained. Lipases immobilized in sol-gel matrices efficiently catalyzed the direct esterification reaction of geraniol and acetic acid in anhydrous hexane to produce geranyl acetate. The optimal formulation of the sol-gel solution for enzyme immobilization was at a 20∶1 molar ratio of water to total silane; a 4∶1 molar ratio of propyltrimethoxysilane to TMOS; hydrolysis time at 30 min; and enzyme loading of 200 mg lipase/g gel. Under these conditions, protein immobilization efficiency was 91%, and the specific activity of the immobilized enzyme was 2.6 times that of the free enzyme. Excellent thermal stability was found for the immobilized enzyme in dry form or in hexane solution in the presence of acetic acid, in which case severe inactivation of free enzyme was observed. The immobilized enzyme retained its activity after heating at 70°C for 2 h, whereas the free enzyme lost 80% of its activity.     

Immobilization of penicillin G acylase onto amino-modified silica hydrogel

Amino-modified silica hydrogel (N-MSHG) was prepared by a simple sol-gel processing via the co-condensation of commercial silica sol with 3-aminopropyltrieoxysilane. Penicillin G acylase (PGA), a model enzyme, was covalently immobilized onto the N-MSHG and then was used for the enzymatic synthesis of amoxicillin. The samples were characterized by Nitrogen sorption analysis, FT-IR and thermal gravimetric analysis (TGA). The results showed that the amino-modified gel was a mesoporous material with an average pore size of 12.64±0.17 nm. The immobilization process was efficient and the immobilized enzyme showed high catalytic efficiency. The yield of the synthesis of amoxicillin in aqueous media was 38% for 2.5 h. This sol-gel preparation is simple and shows prominent potential value in industrial processing.     

Immobilization of penicillin G acylase onto amino-modified silica hydrogel

Amino-modified silica hydrogel (N-MSHG) was prepared by a simple sol-gel processing via the co-condensation of commercial silica sol with 3-aminopropyltrie-oxysilane. Penicillin G acylase (PGA), a model enzyme, was covalently immobilized onto the N-MSHG and then was used for the enzymatic synthesis of amoxicillin. The samples were characterized by Nitrogen sorption analysis, FT-IR and thermal gravimetric analysis (TGA). The results showed that the amino-modified gel was a mesoporous material with an average pore size of 12.64±0.17nm. The immobilization process was efficient and the immobilized enzyme showed high catalytic efficiency. The yield of the synthesis of amoxicillin in aqueous media was 38% for 2.5h. This sol-gel preparation is simple and shows prominent potential value in industrial processing.     

Structural characteristics and properties of silica/poly(2-hydroxyethyl methacrylate) (PHEMA) nanocomposites prepared by mixing colloidal silica or tetraethyloxysilane (TEOS) with PHEMA

Two methods were used to prepare the silica/poly(2-hydroxyethyl methacrylate) (PHEMA) nanocomposites: one was the direct mixing of colloidal silica with PHEMA using methanol as a co-solvent (colloidal silica/PHEMA) and the other was the adding of the inorganic precursor, tetraethyloxysilane (TEOS), to the PHEMA/methanol solution, followed by the sol-gel process with an acid-catalyst (TEOS/PHEMA). The structure of the colloidal silica/PHEMA hybrid consisted of nano-silica uniformly dispersed in the PHEMA phase with slight inter-molecular hydrogen bonding. The structure of TEOS/PHEMA hybrid was similar to a semi-interpenetrated network with PHEMA chains tethered into the nano-silica network by inter- and intra-molecular hydrogen bonding. Consequently, the TEOS/PHEMA hybrid gels exhibited a smoother surface, higher transparency, and better thermal stability than the colloidal silica/PHEMA hybrid gels.     

二氧化钛光催化剂负载工艺研究进展

介绍了实现纳米T iO2固载化的各种物理方法和化学方法,玻璃、硅胶以及金属等不同载体对纳米T iO2光催化活性的影响。简述了采用的纳米T iO2直接修饰后涂膜、SnO2修饰的纳米T iO2复合溶胶镀膜及纳米T iO2复合电镀成膜三种有效的固载化方法。对其发展前景进行了展望,并指出溶胶法制备复合膜及复合电镀成膜应是很有发展前途的两种方法。