以醋酸纤维素吸水胶囊为载体制备固定化脲酶

把高吸水材料封在具超滤功能的醋酸纤维素（CA）皮膜中，制成胶囊。此胶囊浸泡在脲酶水溶液中，水分受高吸水材料的吸引透过皮膜进入胶囊中，脲酶被截留在CA皮膜上，并且与CA上的活性基团相结合，形成CA胶囊固定化脲酶。     

大豆多糖固定化脲酶

本文以大豆多糖为载体，分别用吸附法与戊二醛交联法固定化脲酶，测得了吸附法的最佳反应温度为６５～７５℃，ｐＨ为６．０～７．０。并对大豆多糖固定化脲酶柱式反应器的动态活性作了初步的测试。     

聚乙烯醇高含水胶固定化脲酶的研究

冷冻-部分脱水法制成的聚乙烯醇高含水胶固定化脲酶活力收率及对脲素的分解能力明显高于聚丙烯酰胺囱定化脲酶,稳定性相近;用低浓度的戊二醛后处理,提高了固定化酶的稳定性。     

固定化脲酶的制备及应用

以壳聚糖作为载体,戊二醛作为交联剂对脲酶进行固定化。固定化的最适条件为:酶的偶联时间60min,戊二醛浓度0.5%,pH值7.0。对游离及固定化脲酶的酶学性质研究表明,酶促反应的最适pH均为7.0,最适温度分别为33℃和70℃。米氏常数分别为29.8mmol/L和13.9mmol/L。与游离酶相比,固定化酶的热稳定性和贮存稳定性更佳。应用固定化酶测定了试样中的微量组分。     

磁性壳聚糖微球用于酶的固定化研究*Ⅲ磁性壳聚糖微球的活化及其对脲酶的固定化研究

以环氧氯丙烷活化的磁性壳聚糖微球作为载体,对脲酶进行固定化研究。结果表明, 在25℃时, 活化磁性壳聚糖微球对脲酶的固定化在2h时就达到了最大值,固定化酶和自由酶的最适温度都在65℃左右,自由酶和固定化酶的米氏常数Km值分别为0.042mol/L和0.008mol/L,固定化酶的Km降低了5倍。     

醋酸纤维素膜及其混合膜渗透气化性能的研究——稀溶液粘度斜率系数的依赖性

研究了醋酸纤维素（CA），乙烯－醋酸乙烯共聚物（EVA），聚乙烯醇缩丁醛（PVB）和聚醋酸乙烯酯（PVAc) 4种高聚物在不同溶剂中的稀溶液粘性行为。同时，从各相应的溶剂中制备了CA均一膜，CA－PVB和CA－PVAc共混膜以及CA－EVA复合膜，并测定了各种膜对甲醇（MeOH），甲基叔丁基醚（MTBE）混合物的渗透气化性能。结果表明，各种膜的渗透通量（J）与其稀溶液粘度斜率系数（b)成反比，即呈现随b值增大J值下降现象。     

PVA固定化脲酶电极的制作及电极特性的研究

利用PVA低温下的物理交联固定酶,制成酶电极并在不同尿素浓度、pH值、温度等条件下进一步研究这种酶电极的响应特性.     

固定化脲酶的制备及酶学性质研究

固定化酶是束缚在一定空间内仍能进行其特有反应的生物催化剂,近年来对于固定化酶的研究非常活跃[1-2].目前酶的固定化方法主要有吸附法,交联法,包埋法以及化学共价法,这些方法各有特点[3-5],应用领域多为食品工业、制药、医学治疗等方面.     

醋酸纤维膜固定过氧化氢酶电极的研究

本将过氧化氢酶与经活化处理的醋酸纤维膜共价固定，并与氧电极偶合，研制成静态和流通二种过氧化氢生物电极。研究了醋酸纤维膜的活化、酶的固定化、测试介质等有关的实验条件和参数。测得静态和流通二种电极响应的线性范围分别为６．７×１０＾－５￣２．０×１０＾－３ｍｏｌ／Ｌ和１．３×１０＾－４￣１．０×１０＾－３ｍｏｌ／Ｌ。将电极用于实际试样中的回收率测定时，获得了较好的结果。     

三醋酸纤维素/醋酸纤维素正渗透膜的制备工艺对性能的影响

通过相转变法制备了一系列三醋酸纤维素/醋酸纤维素正渗透膜,并探索了影响正渗透膜水通量的三个重要因素:膜厚度、凝胶时间、热处理过程。结果表明膜厚度为300mm、凝胶时间48 h,并经过热处理以后的正渗透膜水通量效果最佳,达到7.088 L/m~2·h。     

纳米纤维素晶须的表面醋酸酯化改性及复合材料的力学性能

采用硫酸水解法制备纳米纤维素晶须, 再以冰醋酸为分散介质, 浓硫酸为催化剂, 醋酸酐为酯化剂对纳米纤维素晶须进行不同程度醋酸酯化改性, 得到醋酸酯化的纳米纤维素. 采用红外光谱(FTIR)、 X射线光衍射(XRD)、 透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对改性产物进行分析和表征. 结果表明, 改性纳米纤维素晶须中醋酸酯基的平均取代度过小或过大时均不适宜用作复合材料的增强相. 当改性纳米纤维素晶须中醋酸酯基的平均取代度为0.05时, 醋酸酯化反应只发生在纳米纤维素晶须的表面. 此时, 晶须能在丙酮中稳定悬浮, 表现出流动双折射现象, 并保持了改性前纳米纤维素晶须的棒状形态和高结晶度. 将这种改性后的纳米纤维素晶须作为增强相与醋酸纤维素通过溶液浇铸法制成纳米复合膜, 结果显示, 与空白醋酸纤维素膜相比, 添加改性纳米纤维素晶须后, 纳米复合膜的拉伸强度、 杨氏模量和断裂伸长率都得到了提高. 在玻璃化转变区间纳米复合膜储能模量的降低幅度小于空白膜.     

Amperometric Glucose Determination by Means of Glucose Oxidase Immobilized on a Cellulose Acetate Film: Dependence on the Immobilization Procedures

Glucose microelectrodes were prepared by immobilizing glucose oxidase onto a cellulose acetate film coating a platinum wire. Hexamethylenediamine (HMDA) and Glutaraldehyde (GA) were employed as spacer and coupling agent, respectively. Sensitivities and linear response ranges were studied as a function of the relative amounts of HMDA and GA. The best sensitivity was found when HMDA and GA were 5% and 2.5% in aqueous solutions, respectively. Taking as a reference the functioning of this biosensor, the roles of HMDA and GA percentages appear to be opposed when the extension of the linear response range is considered. Indeed, an increase of one unit in HMDA percentage (from 5 to 6 %) induces an increase in the extension of the linear response range equal to that obtained with a decrease of one unit of GA percentage (from 2.5 to 1.5%).     

PA-130/CA合金膜材料的研制及其性能

采用溶液共混和液-固相转变法(L-S)制备了用于高效液相色谱(HPLC)柱填料的共聚尼龙/醋酸纤维素共混物(PA-130/CA)。以小分子量化合物为探针分子,用HPLC数据表征了PA-130/CA合金膜材料的界面性能,并研究了其合金膜材料的相容性和热稳定性。结果表明:PA-130与CA有很好的相容性;该合金膜的热稳定性比纯CA膜的有所提高;质量比为30/70的PA-130/CA合金膜对不离解极性有机物的分离效率更高。     

Immobilization of Glucose Oxidase on Cellulose／Cellulose Acetate Membrane and its Detection by Scanning Electrochemical Microscope （SECM）

Cellulose/cellulose acetate membranes were prepared and functionalized by introducingamino group on it, and then immobilized the glucose oxidase (Gox) on the functionalizd membrane.SECM was applied for the detection of enzyme activity immobilized on the membrane.Immobilized biomolecules on such membranes was combined with analysis apparatus and can beused in bioassays.     

污染肝素中多硫酸化硫酸软骨素的分步醋酸纤维素薄膜电泳分析

采用离子交换色谱法从污染肝素原料中分离出多硫酸化硫酸软骨素(OSCS),建立了分步醋酸纤维素薄膜电泳法分析污染肝素中OSCS含量的方法.结果表明,先以0.05 mol/L醋酸钡缓冲液(pH 5.0)电泳,再以0.15 mol/L醋酸锌缓冲液(pH 6.3)电泳,可以将肝素和OSCS完全分开,检出限为0.1 g/L; 通过灰度积分建立定量校准曲线,相关系数为0.9934,平均回收率为102.1%～106.1%; RSD为4.1%～6.0%.     

Stability Improvement of Prussian Blue by a Protective Cellulose Acetate Membrane for Hydrogen Peroxide Sensing in Neutral Media

The cellulose acetate covered Prussian blue modified glassy carbon electrode (GCE/PB/CA) was fabricated as a novel hydrogen peroxide sensor. It was shown by scanning electron microscope (SEM) and atomic force microscope (AFM) that Prussian blue was covered and protected by cellulose acetate perfectly. The modified electrode showed a good electrocatalytic activity for H₂O₂ reduction in neutral aqueous solution. H₂O₂ was detected amperometrically in 0.05 mol/L phosphate buffer solutions (pH 7.0, containing 0.1 mol/L KCl as supporting electrolyte) at an applied potential of ?0.2 V (vs. SCE). The response current was proportional to the concentration of H₂O₂ in the range of 1.0×10^?5 mol/L to 2.5×10^?4 mol/L with the detection limit of 2.2×10^?6 mol/L at a signal to noise ratio 3.     

均相与非均相法合成的纤维素乙酸酯结构与性能的比较研究

研究了离子液体中均相反应制备纤维素乙酸酯(CA_(Homo))与非均相反应制备纤维素乙酸酯(CA_(Hete))的化学结构,进而比较了化学结构差别对纤维素乙酸酯性能的影响.均相与非均相法制备的CA化学结构存在显著差异,CA_(Homo)相比CA_(Hete)具有更好的均匀性,且CA_(Homo)和CA_(Hete)的取代基分布不同,CA_(Homo)的乙酰基取代顺序为C-6C-3C-2,CA_(Hete)的乙酰基取代顺序为C-3C-2C-6.同时对CA_(Homo)和CA_(Hete)的结晶行为、溶解性和热性能进行研究,结果表明,不同化学结构对CA的这些宏观性能影响较小,CA_(Homo)和CA_(Hete)均为无定型结构,可溶解于极性有机溶剂中,玻璃化转变温度和热稳定性相近.因此,通过离子液体均相制备的CA与现有非均相法制备的CA具有相似的物理性能,但均相法制备的CA结构均匀性更好.     

The Successful Use of Cellulose Acetate Membrane for Very Low Density Lipoprotein Isolation and Cholesterol Quantitation

Abstract

The lipoproteins have been successfully isolated electrophoretically from the blood samples of patients having suffered from hyperlipoproteinemia type III but having survived myocardial infarction. The VLDL fraction from the cellulose acetate membrane is cut out and the total cholesterol and cholesterol of the VLDL extracted. The cholesterol is determined using an immobilized cholesterol esterase/oxidase column using a flow injection analysis system.