介孔SiO2的改性及对诺维信漆酶的交联固定化

采用十六烷基三甲基溴化铵(CTAB)为模板剂,四乙氧基硅烷(正硅酸乙酯,TEOS)为硅源,硝酸为催化剂来制备介孔SiO2,并采用后嫁接法对介孔SiO2进行氨基化改性。利用红外光谱(IR),X射线粉末衍射(XRD),差热-热重分析(DTA-TG),扫描电镜(SEM),元素分析,微电泳法及N2吸附-脱附方法对改性前后的产物进行表征。结果表明氨基已成功嫁接到介孔SiO2孔道中,改性后的介孔SiO2有序度有所下降,但仍为介孔材料;改性之后介孔材料的孔径、比表面积、孔体积均变小。等电点由原来的2.74变为4.75。本文还以氨基修饰的介孔SiO2为载体,通过交联剂戊二醛固定诺维信(Novozymes)工业级漆酶,并采用正交设计法对固定化条件进行了优化。研究表明漆酶经固定化后,其操作稳定性比游离酶高。     

A General Strategy for Site‐Directed Enzyme Immobilization by Using NiO Nanoparticle Decorated Mesoporous Silica

Mesoporous materials have recently gained much attention owing to their large surface area, narrow pore size distribution, and superior pore structure. These materials have been demonstrated as excellent solid supports for immobilization of a variety of proteins and enzymes for their potential applications as biocatalysts in the chemical and pharmaceutical industries. However, the lack of efficient and reproducible methods for immobilization has limited the activity and recyclability of these biocatalysts. Furthermore, the biocatalysts are usually not robust owing to their rapid denaturation in bulk solvents. To solve these problems, we designed a novel hybrid material system, mesoporous silica immobilized with NiO nanoparticles (SBA‐NiO), wherein enzyme immobilization is directed to specific sites on the pore surface of the material. This yielded the biocatalytic species with higher activity than free enzyme in solution. These biocatalytic species are recyclable with minimal loss of activity after several cycles, demonstrating an advantage over free enzymes.     

二氧化硅纳米与微米颗粒作为固定化酶载体的生物效应

分别将二氧化硅纳米颗粒(SiNPs)与微米颗粒(SiMPs)作为固定化载体, 选择多聚酶牛肝过氧化氢酶(CAT)和单体酶辣根过氧化物酶(HRP)作为酶模型, 通过考察酶固定化后在酶活回收率、热稳定性、 酶促反应最适温度以及酶在水-有机溶剂混合体系中催化能力的变化, 对载体与酶所产生的生物效应差异进行了系统研究. 酶活回收率结果表明, SiNPs显示出比SiMPs优越的对酶无选择性的高生物亲和性, 而SiMPs则能使固定于其上的酶热稳定性大幅度提高, 且二者都能使固定化酶在有机相中的稳定性得到明显增强. 但酶促反应最适温度的变化结果表明, 对不同类型的酶所产生的生物效应则表现出无规律性.     

Immobilization of Rhodococcus AJ270 and Useof Entrapped Biocatalyst for the Productionof Acrylic Acid

Summary.  Rhodococcus AJ270 is adsorbed by Dowex 1 at 15.4  mg dry weight per g resin with maximum amidase specific activity observed at lower loadings. Bacteria form a monolayer on the resin surface, and adsorption is complete within 2 min. AJ270 can be entrapped in agar and agarose gels (optimum loading: 20 mg dry weight bacteria per cm³ gel). Adsorption and entrapment improve amidase thermal stability 3–4 fold, and entrapment shifts the pH optimum from 8 to 7. Adsorbed and free bacteria show similar values for K _m and V _max, but entrapped bacteria have higher K _m values. Compared with bacteria adsorbed to Dowex, the activity per cm³ of matrix of agar-entrapped AJ270 is eight-fold higher. In stirred-tank reactors, exposure to acrylic acid reduces the amidase activity of the biocatalyst in the hydrolysis of acrylamide. In column reactors, entrapped AJ270 suffers little reduction in amidase activity against 0.25 M acrylamide over 22 h continuous operation. Received November 18, 1999. Accepted December 14, 1999     

Phosphine-Functionalized Syndiotactic Polystyrenes: Synthesis and Application to Immobilization of Transition Metal Nanoparticle Catalysts

The precise control of monomer sequence and stereochemistry in copolymerization is of much interest and importance for the synthesis of high performance materials, but studies toward this goal have met with only limited success to date. The coordination polymerization of diphenylphosphinostyrene (p-StPPh₂ and o-StPPh₂) and its copolymerization with styrene (St) by (C₅Me₄SiMe₃)Sc(CH₂C₆H₄NMe₂-o)₂ have been achieved for the first time to afford a new series of phosphine functionalized syndiotactic polystyrene. By the design of the polymer structure, the copolymer of o-StPPh₂ and St (poly(o-StPPh₂-alt-St)-b-sPS) containing o-StPPh₂ and St atactic alternating copolymer block and syndiotactic polystyrene block (sPS) showed excellent thermal stability and chemical resistance. The simple combination of the triphenylphosphine and syndiotactic polystyrene realized the stable immobilization of metal nanoparticles to afford highly robust metal@poly(o-StPPh₂-alt-St)-b-sPS nanocatalysts at high temperature and various atmospheres. The Cu@poly(o-StPPh₂-alt-St)-b-sPS catalyst can serve as a highly efficient heterogeneous catalyst for the synthesis of quinoline derivatives by acceptorless dehydrogenative coupling of o-aminobenzylalcohol with ketones.     

硅胶的表面硫醇化改性及对水溶液中罗丹明B的固载

运用γ-巯丙基三乙氧基硅烷对硅胶表面硫醇化修饰改性,红外及拉曼光谱分析表明硅胶的表面硫醇化借助硅胶表面羟基与γ-巯丙基二乙氧基硅烷间的化学键联实现。实验条件下改性硅胶对水体罗丹明B的吸附性能明显提升,改性硅胶表面罗丹明B的吸附动力学符合准二级动力学模型,吸附等温线服从Langmuir等温线规律,由等温吸附计算得到的热力学函数变化表明吸附系自发、放热过程。吸附动力学、热力学及光谱表征均表明改性硅胶上罗丹明B的吸附主要为其在改性硅胶表面借助电价和共价键联的化学吸附。     

硅胶固定功能化离子液体的制备及其在HMF合成中的应用

通过氯丙基三甲氧基硅烷将磺基功能化离子液体--N-磺丙基咪唑盐化学键联到微球硅胶上,制得微球硅胶固定化离子液体（IL3）。用FTIR、TG、13C-NMR、SEM、BET及酸度测定等方法对IL3进行了表征,并考察其在果糖脱水合成5-羟甲基糠醛（HMF）过程中的催化性能。研究结果表明：氯丙基三甲氧基硅烷可以将磺基功能化咪唑型离子液体化学键联到微球硅胶上。微球硅胶固定化磺基咪唑离子液体能有效催化果糖脱水生成HMF。在45.4-IL3催化下、乙二醇甲醚(EGME)溶剂中、115℃反应5小时, HMF收率可达82.1％。使用后的催化剂可以方便地循环使用。但随次数增加,HMF收率明显下降。45.4-IL3催化剂循环使用四次后,HMF的收率下降为53.0%。     

硅胶的表面硫醇化改性及对水溶液中罗丹明B的固载

运用γ-巯丙基三乙氧基硅烷对硅胶表面硫醇化修饰改性, 红外及拉曼光谱分析表明硅胶的表面硫醇化借助硅胶表面羟基与γ-巯丙基二乙氧基硅烷间的化学键联实现。实验条件下改性硅胶对水体罗丹明B的吸附性能明显提升, 改性硅胶表面罗丹明B的吸附动力学符合准二级动力学模型, 吸附等温线服从Langmuir等温线规律, 由等温吸附计算得到的热力学函数变化表明吸附系自发、放热过程。吸附动力学、热力学及光谱表征均表明改性硅胶上罗丹明B的吸附主要为其在改性硅胶表面借助电价和共价键联的化学吸附。     

Solvothermal Synthesis of Functional Magnetic Nanoparticles for Biocatalyst

A facile and simple one-step solvothermal method has been developed to synthesize polyethyleneimine (PEI)-modified magnetic nanoparticles. Characterization of morphology, surface charges, crystal structure, and magnetic property confirmed the efficiency of this facile synthesis route. Lipase immobilized on the PEI-modified magnetic nanoparticles was used to synthesize vitamin A palmitate from vitamin A acetate and palmitic acid. The reuse of immobilized lipase can be extended to eight times by removing water during esterification with a conversion rate above 80 % for 12 h.     

Synthesis and Characterization of a Photoluminescent Nanoparticle Based on Fullerene–Silica Hybridization

Bright lights : Fullerene–silica hybrid nanoparticles have bright photoluminescence, high photostability, and low cytotoxicity, which are assets for bioimaging agents. The origin of the photoluminescence of the nanoparticle is the C–O–Si bond (see picture).

     

硅胶表面扑灭津分子印迹材料的制备及性能表征

以扑灭津为模板分子,在甲苯溶液中经三步反应合成了基于硅胶表面修饰的分子印迹聚合物,并探讨了聚合物制备工艺,验证了聚合物的结构。红外1726cm-1指认印迹膜中的羰基特征峰,元素分析表明印迹材料含碳量18%,N2吸附实验表征印迹膜厚度为0.3nm。应用高效液相色谱-质谱考察了扑灭津和其它3种三嗪农药水溶液中的竞争吸附特性。研究表明:本法制备的表面印迹材料对4种三嗪类农药的吸附均优于参比材料。     

硅胶固定功能化离子液体的制备及其在5-羟甲基糠醛合成中的应用

通过γ-氯丙基三甲氧基硅烷将磺基功能化离子液体-N-磺丙基咪唑盐化学键合到微球硅胶上,制得微球硅胶固定化离子液体(IL3). 用FTIR、TG、~(13)C NMR、SEM、BET及酸度测定等测试技术对IL3进行了表征,并考察其在果糖脱水合成5-羟甲基糠醛(HMF)过程中的催化性能. 研究结果表明,氯丙基三甲氧基硅烷可以将磺基功能化咪唑型离子液体化学键合到微球硅胶上. 微球硅胶固定化磺基咪唑离子液体能有效催化果糖脱水生成HMF. 果糖在固载率45.4%的IL3催化下、乙二醇甲醚(EGME)溶剂中、115 ℃反应5 h,HMF收率可达82.1%. 催化剂循环使用4次后,HMF的收率下降为53.0%.     

介孔碳的快速水相合成及对辣根过氧化物酶的固定

以间苯三酚-甲醛为碳源前驱体, 嵌段聚合物F127 (PEO₁₀₆PPO₇₀PEO₁₀₆)为模板剂, 在水相中快速合成了介孔碳材料. 将其应用于辣根过氧化物酶的固定化, 并初步研究了固定化对酶稳定性的影响. 利用TEM和SEM观察该材料的微观结构, 通过N₂吸附-脱附技术对介孔碳材料的孔结构和孔容等进行了表征. 结果表明, 介孔碳材料具有蠕虫状介孔结构, 孔径可在5.6～7.6 nm之间调变, 相应的比表面积介于691.1～787.8 m²/g, 且随着反应体系中盐酸浓度的增加, 所得材料的孔径、比表面积和孔容等均呈现减小的趋势. 固定在介孔碳中的辣根过氧化物酶, 保持了其蛋白质二级结构, 且与游离酶相比, 固定化酶的热稳定性、pH稳定性和操作稳定性都有明显的提高. 经多次循环操作, 固定化酶依然保持较高的活性, 说明其具有良好的可重复利用价值.     

聚酰胺-胺树状大分子修饰硅胶固定化胰蛋白酶的研究

以聚酰胺-胺(PAMAM)树状大分子修饰的硅胶为载体,胰蛋白酶为模型,考察了PAMAM的代数和固定化条件对酶的固载量及活力的影响.实验结果表明:选用3.0代PAMAM树状大分子修饰硅胶为载体固定化胰蛋白酶,酶促反应最适pH值为9.0,最适温度为60℃,对酪蛋白表现米氏常数K<,m>为7.76mg/mL,固定化胰蛋白酶表...     

醚型十八烷基键合硅胶整体柱的制备及其评价

将硅烷偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560)先与十八醇反应,再键合到硅胶整体柱上,得到醚型十八烷基键合硅胶整体柱,并用红外光谱对其进行了表征.利用该固定相,在甲醇-水简单的二元流动相体系下,考察了该整体柱适用的pH范围,以及流速与柱压降和流速与柱效的关系,用该固定相对苯及其同系物进行了分离,并对尼群地平、硝苯地平和间尼索地平进行了分离.结果表明,该硅胶整体柱键合效果良好,具有较好的反相色谱性能,且在pH=2～8范围内稳定性好,柱压降、柱效受流速影响较小,可有效地用于化合物的快速分离分析.     

硅基分子筛及其在精细化学品合成中的应用*

本文综述了沸石分子筛及中孔硅基材料在合成方面的最新进展,总结了这类分子筛材料在精细化学品合成中的应用及取得的成果,详细介绍了中孔分子筛的表面改性尤其是有机－无机杂化分子筛的合成、性质、特点及其作为催化剂在有机合成反应中的应用。     

酶的固定化及其应用

酶的固定化研究始于1960年代中期,从1970年代初开始酶的固定化技术研究发展很快,至1980年代初,每年约发表1000篇以上的文献和近200篇专利,所报道的固定化方法达100种以上[1].1980年代中以后,酶和细胞固定化研究的发展速度开始减慢,从而有人认为,对酶的固定化技术应予以重新评价     

Effect of Method Used for Synthesis of Silica Sols on Pore Characteristics of Silica Gels on Their Base

Problems associated with synthesis of silica gels with prescribed pore characteristics from stabilized silica sols with controlled colloid particle size, obtained in the metastable solubility region of the system SiO₂-H₂O (8.5-9.5), are considered.