再生丝素固定葡萄糖氧化酶及其传感器应用

再生丝素固定葡萄糖氧化酶及其传感器应用钱江红，刘永成，刘海鹰，于同隐，邓家祺（复旦大学化学系高分子科学系，上海，２００４３３）关键词再生丝素，葡萄糖氧化酶，传感器，酶电极酶电报的各项性能在很大程度上取决于酶的固定比方法，葡萄糖氧化酶的固定化方法很多１...     

再生丝素和聚乙烯醇混合膜的结构、性能及其葡萄糖传感器的应用

用扫描电镜分析了再生丝素(RSF)和聚乙烯醇(PVA)混合膜的形貌结构,并测定了其吸水性和机械强度,用RSF和PVA的混合材料把葡萄糖氧化酶固定在玻碳电极表面,制成电流型葡萄糖传感器,以1,4-苯醌为电子传递体,酶电极对葡萄糖有灵敏的响应,峰电流的增加与葡萄糖的浓度在10^-5～10^-2mol/L范围内有良好的线性关系。用此方法制成的葡萄糖传感器物理性能好,其有效寿命长达2个月以上。该酶电极对葡萄糖的响应时间小于20s.     

用再生丝素固定过氧化物酶及其传感器在有机相中的研究

用再生丝素固定过氧化物酶及其传感器在有机相中的研究钱江红，刘永成，刘海鹰，于同隐，邓家祺（复旦大学化学系、高分子科学系，上海，２００４３３）关键词再生丝素，生物传感器，过氧化氢酶在非水介质中的催化活性已有研究［１］，生物传感器在有机相中有许多优点：如...     

用桑蚕丝素蛋白固定的葡萄糖氧化酶传感器

目前,常用的生物酶固定化方法在应用上各有优劣,简便、高效而又适用推广的酶固定化方法是人们所追求的目标。本文提供一种新型的酶固定化方法,即通过蚕丝素蛋白在甲醇中变性,使葡萄糖氧化酶(GOD)固定在蛋白质中,得到葡萄糖氧化酶-丝素膜,与氧电极偶合,制成电流式葡萄糖传感器。在选定的实验条件下,电极的各项性能指标均较满意。 GOD由Boehringer Mannhen GmbH进口(10 kU/46 mg),试剂均为分析纯。家蚕(浙12×苏1)由浙江农业大学提供。氧电极和测氧仪由中国科学院上海冶金研究所制造。     

蜘蛛丝素和聚乙烯醇固定葡萄糖氧化酶 制备葡萄糖传感器

用蜘蛛丝素和聚乙烯醇的混合材料把葡萄糖氧化酶固定在氧电极表面,制成葡萄糖氧化酶电极。传感器对葡萄糖有灵敏的响应,平均响应时间为20s,电位变化值与葡萄糖浓度在3.0×10     

再生丝素固定乙酰胆碱酯酶生物传感器

再生丝素固定乙酰胆碱酯酶生物传感器;生物传感器;乙酰胆碱酯酶;再生丝素     

具有定向形貌的丝蛋白支架的制备

利用冰晶为模板并结合冷冻干燥技术, 成功地获得了具有一定力学强度的定向多孔丝蛋白支架. 采用扫描电镜、流变、拉曼光谱和压缩测试等方法, 考察了丝蛋白原液在不同pH值和初始浓度的情况下对定向支架的成因、内部形貌及力学性能的影响. 结果表明, 当溶液的pH值为4.4, 浓度由低到高时, 所制备的丝蛋白支架内部将分别出现纤维状结构、轴向片层状和梭状多孔结构. 特别是由初始浓度为15% (及以上)的丝蛋白溶液定向冷冻得到的支架, 在压缩试验中表现出较好的力学性能, 其轴向压缩模量和屈服应力分别达122.6和6.9 MPa, 满足了进一步应用的基本需求.     

Fractionation of Regenerated Silk Fibroin and Characterization of the Fractions

The molecular weight (MW) of regenerated silk fibroin (RSF) decreases during degumming and dissolving processes. Although MW and the MW distribution generally affect polymer material processability and properties, few reports have described studies examining the influences of MW and the distribution on silk fibroin (SF) material. To prepare different MW SF fractions, the appropriate conditions for fractionation of RSF by ammonium sulfate (AS) precipitation process were investigated. The MW and the distribution of each fraction were found using gel permeation chromatography (GPC) and SDS-polyacrylamide electrophoresis (SDS-PAGE). After films of the fractionated SFs formed, the secondary structure, surface properties, and cell proliferation of films were evaluated. Nanofiber nonwoven mats and 3D porous sponges were fabricated using the fractionated SF aqueous solution. Then, their structures and mechanical properties were analyzed. The results showed AS precipitation using a dialysis membrane at low temperature to be a suitable fractionation method for RSF. Moreover, MW affects the nanofiber and sponge morphology and mechanical properties, although no influence of MW was observed on the secondary structure or crystallinity of the fabricated materials.     

类珍珠质结构的再生丝素蛋白/文石复合材料的仿生制备

详细研究了不同浓度的聚丙烯酸(分子量为2000, PAA-2k)和镁离子对碳酸钙在再生丝素蛋白(RSF)膜表面结晶的影响. 发现单独采用PAA-2k时, 碳酸钙主要以方解石形式在RSF膜表面沉积成膜; 若加入一定量的镁离子参与共同调控, 碳酸钙则有可能在RSF膜表面形成以文石为主的连续薄膜, 进而得到了具有类珍珠质结构的层状RSF/文石复合材料. 我们认为, 吸附在RSF膜表面的PAA对碳酸钙成核诱导作用及其溶液中PAA对碳酸钙结晶抑制作用共同导致RSF膜表面碳酸钙薄膜的形成.     

纳米TiO2/丝素复合膜的制备

探讨了纳米TiO2在丝素溶液中的分散条件,在此基础上制备了纳米TiO2/丝素复合膜,并用原子力显微镜(AFM)和扫描电子能谱(EDS)对复合膜进行了表征。实验结果表明,制膜方法较为合理。当以有机物A为分散剂,纳米TiO2含量为1/1000时,其以粒径50 nm左右均匀地分散于复合膜中。     

桑蚕丝素蛋白的结构、形态及其化学改性

通过对桑蚕吐丝机构的描述,着重从高分子科学的角度介绍桑蚕丝和蚕丝素蛋白大分子的组成、形态及各种化学、物理性质,讨论了蚕丝素蛋白的纤维化机理,并简述了丝索蛋白纤维的化学接枝改性及其应用。     

Amperometric Glucose Sensor Fabricated by Combining Glucose Oxidase Micelle Membrane and Aminated Glassy Carbon Electrode

Abstract

An amperometric glucose biosensor based on the detection of the reduction of oxygen has been developed by combining an aminated glassy carbon electrode with a polystyrene (PS) membrane containing glucose oxidase (GOD) micelles. The structure of GOD micelles contained in PS membrane was observed by scanning electron microscope. The micelle has a roughly spherical shape, and the enzyme colony is contained inside the micelle. This glucose sensor exhibited good sensitivity with short response time (within 2 min). A good linear relationship was observed in the concentration range of 0.2 mM to 2.6 mM when the applied potential was ? 0.45 V vs. Ag/AgCl.     

Silk Sericin Retards the Crystallization of Silk Fibroin

Summary: The thermal and structural analysis of silk fibroin (SF) and silk sericin (SS) blend films reveals that the crystallization of SF is retarded in the presence of SS. Although a phase separation was observed, there might be a strong interaction at the boundary of the SF and SS through intermolecular hydrogen bonding, which restricts the conformational transition of SF.

TEM image of the cross‐section of the SF/SS blend (75:25) film (magnification: ×15 000).     

Preparation of Crosslinked Chitosan/Silk Fibroin Blend Films for Drug Delivery System

Crosslinked chitosan/silk fibroin blend films were prepared by a solution casting technique using glutaraldehyde as crosslinking agent. Drug release characteristics of the blend films with various blend compositions were investigated. Theophylline, diclofenac sodium, amoxicillin trihydrate, and salicylic acid were used as model drugs. The release studies were performed at 37 °C in buffer solutions at pH 2.0, 5.5, and 7.2. It was found that the blend films with 80% chitosan content showed the maximum amount of model drug release at pH 2.0 for all the drugs studied here. This result corresponded to the swelling ability of the blend films. From a swelling study, the maximum degrees of swelling of the drug‐loaded blend films were obtained at this pH and blend composition. The amount of drugs released from the films with 80% chitosan content, from the highest to the lowest values, occurred in the following sequence: salicylic acid > theophylline > diclofenac sodium > amoxicillin.

Comparison of the amounts of drug released from chitosan and the blend film with 80% chitosan content at pH 2.0: (filled) chitosan film, and (blank) blend film with 80% chitosan content (SAL = salicylic acid, THEO = theophylline, DFS = diclofenac sodium, AMX = amoxicillin).     

柞蚕丝素／纳米TiO2复合膜的制备及其结构表征

为了获得良好性能的柞蚕丝素复合膜,本文采用复合法制备了不同配比柞蚕丝素/纳米TiO2复合膜,并与纯的丝素膜作了比较,用SEM、DSC、TG和IR进行了表征.SEM测试表明在分散剂聚乙烯醇作用下,适量的纳米TiO2能均匀分散丝素溶液中.DSC测试表明复合膜b、c和d的Tm均高于纯的柞蚕丝素膜a的Tm,然而随着纳米TiO2加入量的继续增加,对应复合膜的Tm有所降低.TG结果表明,随着纳米TiO2加入量的增加,复合膜的热稳定性得到提高.IR测试表明丝素复合膜的结晶结构从Silk I向SilkII转化.     

葡萄糖氧化酶共价交联于蛋膜上的葡萄糖传感器

以牛血清白蛋白－戊二醛为交联剂，将葡萄糖氧化酶固定地鸡蛋膜上，氧电极作电化学敏感元件，制成葡萄糖氧化酶电极。传感器的响应范围为４．０×１０＾－６－２．４×１０＾－３ｍｏｌ／Ｌ；检测限为１．２１０＾－６ｍｏｌ／Ｌ。该传感器具有线性范围宽，灵敏度高，使用寿命长等优点。     

Silk Fibroin/Wool Keratin Composite Scaffold with Hierarchical Fibrous and Porous Structure

The present study describes a silk microfiber reinforced meniscus scaffold (SMRMS) with hierarchical fibrous and porous structure made from silk fibroin (SF) and wool keratin (WK) using electrospinning and freeze-drying technology. This study focuses on the morphology, secondary structure, mechanical properties, and water absorption properties of the scaffold. The cytotoxicity and biocompatibility of SMRMS are assessed in vivo and in vitro. The scaffold shows hierarchical fibrous and porous structure, hierarchical pore size distribution (ranges from 50 to 650 µm), robust mechanical properties (compression strength can reach at 2.8 MPa), and stable biodegradability. A positive growth condition revealed by in vitro cytotoxicity testing indicates that the scaffold is not hazardous to cells. In vivo assessments of biocompatibility reveal that only a mild inflammatory reaction is present in implanted rat tissue. Meniscal scaffold made of SF/WK composite shows a potential application prospect in the meniscal repair engineering field with its development.     

Spherulites of Tussah Silk Fibroin. Structure, thermal properties and growth rates

The crystal structure, thermal properties and growth rates of spherulites of the Tussah silk fibroin, produced upon drying of the silk taken directly from the lumen which is essentially a poly(L-alanine)polypeptide, are investigated. Depending on casting conditions, spherulites with either αhelical chain conformation or β parallel sheet structure are produced. The growth rates display a strong positive temperature coefficient, with an apparent transition, which however cannot be related with the formation of two different crystal structures at this stage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Silk Fibroin Degradation Related to Rheological and Mechanical Properties

Regenerated silk fibroin has been proposed as a material substrate for biomedical, optical, and electronic applications. Preparation of the silk fibroin solution requires extraction (degumming) to remove contaminants, but results in the degradation of the fibroin protein. Here, a mechanism of fibroin degradation is proposed and the molecular weight and polydispersity is characterized as a function of extraction time. Rheological analysis reveals significant changes in the viscosity of samples while mechanical characterization of cast and drawn films shows increased moduli, extensibility, and strength upon drawing. Fifteen minutes extraction time results in degraded fibroin that generates the strongest films. Structural analysis by wide angle X‐ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR) indicates molecular alignment in the drawn films and shows that the drawing process converts amorphous films into the crystalline, β‐sheet, secondary structure. Most interesting, by using selected extraction times, films with near‐native crystallinity, alignment, and molecular weight can be achieved; yet maximal mechanical properties for the films from regenerated silk fibroin solutions are found with solutions subjected to some degree of degradation. These results suggest that the regenerated solutions and the film casting and drawing processes introduce more complexity than native spinning processes.