介孔二氧化硅载体在酶蛋白固定化中的应用

介孔二氧化硅材料因制备简单、生物相容性良好、比表面积和孔径可控、表面修饰基团多样等特点,被广泛应用于酶蛋白的固定化。主要综述了介孔二氧化硅对水解酶、氧化还原酶等酶蛋白的固定化效果及其影响固定化效果的因素,展望了介孔二氧化硅在酶蛋白固定化中的应用前景及存在的挑战,为介孔二氧化硅更好地应用于固定化酶制剂的制备奠定基础。     

介孔材料SBA-15固定化脂肪酶的研究进展

介孔材料由于其孔道分布有序且孔径均匀等优点而在固定化酶催化领域引起人们的广泛关注.本文综述了新型介孔材料SBA-15对脂肪酶固定化的研究进展.总结了SBA-15的孔径大小、形貌及等电点等因素对脂肪酶固定化的影响.归纳了SBA-15上三种不同固定化方法的优缺点,并介绍了SBA-15固定化脂肪酶在手性拆分、酯水解、酯合成及转醇化反应等领域的应用.最后提出SBA-15固定化脂肪酶在发展过程中存在的问题以及今后的发展趋势.     

介孔材料固定化酶的标准研究及应用前景

本文主要就介孔材料固定化酶的最新研究进予以简述,重点针对酶分子在被固载于介孔材料的纳米孔后,纳米孔的直径大小以及孔微环境将会对固定化酶的催化活性及稳定性所产生的影响进行了标准探究。而后,文章就介孔材料固定化酶在生物传感器、生物柴油、生物质转化以及废水处理等诸多方面等应用前景予以了展望。     

介孔二氧化硅在布洛芬的装载及控释系统中的研究进展

介孔二氧化硅材料因具有规则的孔道结构和形貌、可控的孔道形状和孔径以及很好的生物相容性,成为药物装载及控释系统的研究热点。本文总结了介孔二氧化硅在布洛芬(IBU)的装载及控释系统中的研究进展,系统阐述了介孔材料的孔径孔容、表面官能化及载药、释药方法等因素,对介孔二氧化硅装载IBU及控释效率的影响,并介绍了酶响应性、温度响应性等刺激响应性的装载及控释系统。     

整体型大孔/介孔PDA/SiO2复合材料固定化漆酶及其在染料降解中的应用

用硬模板法制得具有三维连续贯通孔道结构的整体型大孔/介孔SiO₂，通过多巴胺（DA）在大孔/介孔SiO₂孔道表面的原位氧化聚合，制得聚多巴胺（PDA）功能化修饰的整体型大孔/介孔复合材料（PDA/SiO₂）。应用SEM、BET、FTIR和TG等技术对修饰前后的材料进行表征。以PDA/SiO₂为载体固定诺维信工业级漆酶，系统研究了pH、固定化时间、漆酶初始浓度及温度对漆酶固定化的影响；以偶氮荧光桃红作为模拟污染物，研究了固定化漆酶对染料的催化降解性能。结果显示，在漆酶浓度为80mg/mL、pH为4.0、固定化时间为6h及固定化温度为25℃时，固定化漆酶酶活达到最高（348.9U/g）。在偶氮荧光桃红浓度为10mg/L、pH为7.0、温度为30℃、降解时间为8h时，固定化漆酶对偶氮荧光桃红脱色率 ≥ 99.9%，且固定化漆酶易从反应体系中分离，重复使用性能良好。     

有序介孔碳材料的模板化构筑及水处理应用研究

介孔碳材料是指孔径介于2 nm-50 nm的一类多孔碳材料。有序介孔碳材料，具有比表面积高、孔道结构规则有序、孔径分布狭窄、孔径大小可调控、表面易于修饰等结构特点和高机械强度、强吸附能力、化学惰性等性能特点，在诸多领域得到了广泛应用，特别是其作为新型吸附剂在水处理领域具有广阔的发展前景。有序介孔炭材料的制备方法主要有硬模板法和软模板法。模板和碳源的选择是控制有序介孔碳材料结构和性能的关键因素。本文从有序介孔硅、天然矿物、MOFs材料、嵌段共聚物等不同模板的角度对有序介孔碳、多级有序微/介孔碳、多级有序大/介孔碳的制备方法进行综述，并对有序介孔碳材料在水处理领域的应用进行简单介绍。     

合成条件对介孔氧化硅材料孔径尺寸的影响

分别在室温酸性、室温碱性、水热碱性条件下合成了介孔氧化硅材料MCM－41,通过XRD,HRTEM,氮气吸附等手段对介孔氧化硅材料进行了表征,并探讨了3种条件下材料介孔尺寸的变化。结果表明：室温酸性条件下合成的MCM－41材料具有最小的介孔尺寸,碱性条件则有利于合成较大孔径的样品。另外还发现无机盐离子的添加、反应温度的变化及煅烧过程均可以影响介孔尺寸,并提出了无机盐离子通过影响表面活性剂胶团的荷电性质和尺寸而改变材料孔径尺寸的模型。     

吸附-交联组合法实现α-淀粉酶在MCM-41上的固定化

以MCM-41介孔分子筛为载体,利用直接吸附法、直接交联法及吸附-交联组合法固定α-淀粉酶。考察了3种方法对固定化时间及酶活力回收率的影响,并对不同方法制备的固定化酶的热稳定性、操作稳定性以及载体的结构与性能进行了研究。结果表明,吸附-交联组合法与直接吸附法或直接交联法相比,α-淀粉酶活力回收率高,可达51%以上;同时,吸附-交联组合法固定化酶的热稳定性和操作稳定性虽略低于直接交联法,但远远高于直接吸附法。XRD和N2物理吸附脱附分析结果表明,MCM-41介孔分子筛固定α-淀粉酶后,其孔径、比表面积和孔容均有所减小,但仍然保持了良好的介孔结构。     

介孔TiO_2固定化葡萄糖氧化酶的直接电化学性能

采用非模板软化学法制备了一种孔径均一的介孔TiO2材料(m-TiO2)。XRD测试结果表明其晶型为锐钛矿,且结晶度高,通过N2吸-脱附曲线可看出存在规整的介孔结构且具有高比表面,从FESEM和TEM可以看出制备的m-TiO2由许多纳米粒子构成微米级大颗粒,且存在均匀分布的介孔。将此种TiO2材料固定化葡萄糖氧化酶(GOx)后,通过红外光谱(FT-IR)分析可知m-TiO2材料可以有效固定化GOx。将m-TiO2作为固定化材料固定化GOx制备成Nafion/GOx/m-TiO2/GC电极并进行相关电化学测试,测试结果表明m-TiO2作为固定化材料固定化GOx后具有良好的催化活性,在无电子媒介体存在下能够实现反应电子与电极表面的直接电子传递,检测线性范围为0.1~1.2 mmol·L?1葡萄糖,灵敏度为3.44?A·mmol?1·L·cm?2,在葡萄糖传感领域具有良好的应用前景。     

青霉素酰化酶固定化载体材料研究进展

就青霉素酰化酶固定化载体材料的研究和应用进行了论述。重点介绍了功能基化高分子聚合物、含环氧基高分子聚合物、离子型层状水滑石和介孔分子筛等新型载体的结构特性和对青霉素酰化酶的固定化作用,并对近年来固定化生物酶载体材料的发展动向和趋势加以评述和展望。     

Trypsin immobilization on mesoporous silica with or without thiol functionalization

The effects of pore size, structure, and surface functionalization of mesoporous silica on the catalytic activity of the supported enzyme, trypsin, were investigated. For this purpose, SBA-15 with 1-dimensional pore arrangement and cubic Ia3d mesoporous silica with 3-dimensional pores were prepared and tested as a support. Materials with varying pore diameters in the range 5–10 nm were synthesized using a non-ionic block copolymer by controlling the synthesis temperature. Thiol-group was introduced to the porous materials via siloxypropane tethering either by post synthesis grafting or by direct synthesis. These materials were characterized using XRD, SEM, TEM, N₂ adsorption, and elemental analysis. Trypsin-supported on the solids prepared was active and stable for hydrolysis of N-α-benzoyl-DL-arginine-4-nitroanilide (BAPNA). Without applying thiol-functionalization, cubic Ia3d mesoporous silica with ca. 5.4 nm average pore diameter was found to be superior to SBA-15 for trypsin immobilization and showed a better catalytic performance. However, enzyme immobilized on the 5% thiol-functionalized SBA-15 prepared by directly synthesis was found to be the most promising and was also found recyclable.     

Trypsin immobilization on mesoporous silica with or without thiol functionalization

The effects of pore size, structure, and surface functionalization of mesoporous silica on the catalytic activity of the supported enzyme, trypsin, were investigated. For this purpose, SBA-15 with 1-dimensional pore arrangement and cubic Ia3d mesoporous silica with 3-dimensional pores were prepared and tested as a support. Materials with varying pore diameters in the range 5–10 nm were synthesized using a non-ionic block copolymer by controlling the synthesis temperature. Thiol-group was introduced to the porous materials via siloxypropane tethering either by post synthesis grafting or by direct synthesis. These materials were characterized using XRD, SEM, TEM, N₂ adsorption, and elemental analysis. Trypsin-supported on the solids prepared was active and stable for hydrolysis of N-α-benzoyl-DL-arginine-4-nitroanilide (BAPNA). Without applying thiol-functionalization, cubic Ia3d mesoporous silica with ca. 5.4 nm average pore diameter was found to be superior to SBA-15 for trypsin immobilization and showed a better catalytic performance. However, enzyme immobilized on the 5% thiol-functionalized SBA-15 prepared by directly synthesis was found to be the most promising and was also found recyclable.     

介孔分子筛SBA-15表面改性对脂肪酶固定化的强化作用

引言 脂肪酶可以催化酯水解或醇解、酯合成、酯交换、多肽合成及高聚物合成等多种有机反应,已被广泛应用于食品、精细化工及制药工业中[1].作为重要的生物催化剂,脂肪酶应用的有效性和经济性很大程度上取决于酶的固定化.     

Nanostructures for enzyme stabilization

Recent breakthroughs in nanotechnology have made various nanostructured materials more affordable for a broader range of applications. Although we are still at the beginning of exploring the use of these materials for biocatalysis, various nanostructures have been examined as hosts for enzyme immobilization via approaches including enzyme adsorption, covalent attachment, enzyme encapsulation, and sophisticated combinations of methods. This review discusses the stabilization mechanisms behind these diverse approaches; such as confinement, pore size and volume, charge interaction, hydrophobic interaction, and multipoint attachment. In particular, we will review recently reported approaches to improve the enzyme stability in various nanostructures such as nanoparticles, nanofibers, mesoporous materials, and single enzyme nanoparticles (SENs). In the form of SENs, each enzyme molecule is surrounded with a nanometer scale network, resulting in stabilization of enzyme activity without any serious limitation for the substrate transfer from solution to the active site. SENs can be further immobilized into mesoporous silica with a large surface area, providing a hierarchical approach for stable, immobilized enzyme systems for various applications, such as bioconversion, bioremediation, and biosensors.     

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.     

Immobilization of lipase in ordered mesoporous materials: Effect of textural and structural parameters

A systematic study dealing with the influence of several parameters on the immobilization of lipase in ordered mesoporous materials (OMM) is presented here. In a first step, a series of OMM have been synthesized trying to cover the most relevant structures. The aim is to get variation in the key properties susceptible of influencing their behavior as lipase supports, such as the structure (cubic or hexagonal), the nature of the pores (channel-like or cage-like), the connectivity of the porous network and the pore size. Also, by following the co-condensation technique, 5–10%-methylated analogues of the pure-silica materials have been prepared. All the samples have been fully characterized with XRD, TEM (including 3D reconstruction), SEM, TGA and N₂ isotherms, and the incorporation of the organic function has been demonstrated by ²⁹Si NMR. All of them have been tested as supports in the immobilization of Candida antarctica Lipase B (CaLB) and the leaching of the enzyme in aqueous media evaluated. With such a systematic approach, valuable information on the influence of the textural properties and the nature of the porous network on the yields of immobilization and enzyme desorption have been stated. Very interestingly, leaching of the enzyme can be diminished until it practically disappears without being covalently bonded to the wall, which places the ordered mesoporous materials at the starting point of a new scenario in enzyme immobilization on preexisting supports.     

Using mesoporous silica materials to immobilise biocatalysis-enzymes

Biocatalysis could gain an enhanced breakthrough with the introduction of novel mesoporous silica materials as enzyme carriers: the dimensions of most of the enzymes are within the pore size range of these new silica materials and a broad spectrum of enzymes can be immobilised. These materials moreover have (i) a uniform pore size distribution, (ii) a high specific surface area and pore volume and (iii) are easy to functionalise. This paper introduces fundamental aspects and techniques to immobilise enzymes on a carrier.     

Carbon nanocage: a large-pore cage-type mesoporous carbon material as an adsorbent for biomolecules

Novel large pore cage type mesoporous carbons, carbon nanocages, abbreviated as CKT (carbon from KIT-5) using three dimensional large cage type face centered cubic Fm3m mesoporous silica materials (KIT-5) as inorganic templates prepared at different temperature were synthesized and characterized. The specific pore volume and the specific surface area of the carbon nanocage materials are much higher as compared to CMK-3 mesoporous carbon. Adsorption of amino acid (histidine), flavonoid (catechin), vitamin (vitamin E, α-tocopherol), endocrine disrupter (nonylphenol), and enzyme (lysozyme) over the carbon nanocage materials was also studied. Interestingly, carbon nanocage materials showed an unusual adsorption capacity of catechin in aqueous solution. The CKT carbon nanocage materials also exhibited higher adsorption capabilities of other biomolecules used in this study as compared with the CMK-3 mesoporous carbon.     

Carbon nanocage: a large-pore cage-type mesoporous carbon material as an adsorbent for biomolecules

Novel large pore cage type mesoporous carbons, carbon nanocages, abbreviated as CKT (carbon from KIT-5) using three dimensional large cage type face centered cubic Fm3m mesoporous silica materials (KIT-5) as inorganic templates prepared at different temperature were synthesized and characterized. The specific pore volume and the specific surface area of the carbon nanocage materials are much higher as compared to CMK-3 mesoporous carbon. Adsorption of amino acid (histidine), flavonoid (catechin), vitamin (vitamin E, α-tocopherol), endocrine disrupter (nonylphenol), and enzyme (lysozyme) over the carbon nanocage materials was also studied. Interestingly, carbon nanocage materials showed an unusual adsorption capacity of catechin in aqueous solution. The CKT carbon nanocage materials also exhibited higher adsorption capabilities of other biomolecules used in this study as compared with the CMK-3 mesoporous carbon.     

Controlling the textural parameters of mesoporous carbon materials

The mesoporous carbon materials prepared by inorganic templating technique using mesoporous silica, SBA-15 as a template and sucrose as a carbon source, have been systematically investigated as a function of sucrose to mesoporous silica composition, with a special focus on controlling the mesoporous structure, surface morphology and the textural parameters such as specific surface area, specific pore volume and pore size distribution. All the materials have been unambiguously characterized by XRD, N₂ adsorption–desorption isotherms, high-resolution transmission electron microscopy, high-resolution field emission scanning electron microscopy, and Raman spectroscopy. It has been found that the porous structure, morphology and the textural parameters of the mesoporous carbons materials, CMK-3-x where x represent the sucrose to silica weight ratio, can be easily controlled by the simple adjustment of concentration of sucrose molecules. It has also been found that the specific surface area of the mesoporous carbon materials systematically increases with decreasing the sucrose to silica weight ratio. Moreover, the specific pore volume of the materials increases from 0.57 to 1.31 cm³/g with decreasing the sucrose to silica weight ratio from 5 to 1.25 and then decreases to 1.23 cm³/g for CMK-3-0.8. HRTEM and HR-FESEM also show a highly ordered pore structure and better surface morphology for CMK-3-1.25 as compared to other materials prepared in this study. Thus, it can be concluded that the sucrose to silica weight ratio of 1.25 is the best condition to prepare well ordered mesoporous carbon materials with good textural parameters, pore structure and narrow pore size distribution.