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1.
Comparative Study of Polymeric Supports as the Base of Immobilisation of Chemically Modified Enzymes
One of the difficulties in using optical biosensors based on enzymatic reactions is the immobilisation of the enzyme involved
in the determination. A detailed study has been carried out of the various polymeric supports which could provide a potential
alternative for the immobilisation of chemically modified enzymes. Before immobilisation, the enzyme is attached by means
of a covalent bond to a fluorescent probe, which is optically active in the visible region. The main advantage of this covalent
bond is that it is possible to follow the enzymatic reaction by fluorescence without the need for immobilising any further
reagent (reagentless biosensors). The results indicate that the most stable and reproducible polymeric supports are derived
from polyacrylamide obtained by UV photopolymerisation. The experiments have been carried out using chemically modified glucose
oxidase as the model enzyme. The films thus obtained have a lifetime of at least two months, an RSD of 9.2%, and a linear
range of 300 to 2000 mg L−1 of glucose. They are completely reversible by regeneration in an appropriate buffer solution. 相似文献
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Kai Zhang Dieter Peschel Erica Brendler Thomas Groth Steffen Fischer 《Macromolecular Symposia》2009,280(1):28-35
Summary: Cellulose derivatives having carboxyl- or carboxymethyl- and sulphate groups were synthesized with control of reaction conditions to regulate the distribution of substituents and molecular weights of the products. Sodium cellulose sulphates (NaCS) were synthesized through acetosulphation of cellulose or direct sulphating of cellulose and cellulose-2.5-acetate (C2.5A). The properties of the products were controlled by choice of starting materials and reaction parameters like reaction temperature and duration. Cellulose sulphates containing carboxyl groups were prepared through oxidation with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO in water or through carboxymethylation with chloroacetic acid after alkali treatment with sodium hydroxide. The biological activity of the products was analyzed with a binding assay to fibroblast growth factor (b-FGF). It was found that NaCS with maximum O-6-sulfation and intermediate to high O-2-sulfation was able to bind b-FGF comparable to natural heparin. Products being sulphated and afterwards carboxymethylated at all three positions were also able to bind substantial quantities of b-FGF. 相似文献
4.
Roland Adden Claes Melander Gunnar Brinkmalm Matthias Knarr Jürgen Engelhardt Petra Mischnick 《Macromolecular Symposia》2009,280(1):36-44
Summary: Six methyl cellulose (MC) samples, one with a DS of 1.32 and five with a DS between 1.83 and 1.88, were degraded with five different enzymes or enzyme preparations containing endoglucanases. The main goal was to investigate whether enzymes could be used for determination of heterogeneity of the substituent distribution along the cellulose chain. To obtain information about the heterogeneity it was necessary to gather information on how the enzymes affect hydrolysis. Monomer composition and methyl distribution in the polymer chain were analyzed after total or partial random hydrolysis and appropriate derivatization by GC and MS, respectively, and used as reference data for the evaluation of the enzymatic hydrolysis. Size exclusion chromatography with multi angle light scattering and refractive index detection (SEC-MALLS/RI) was used to estimate molar mass distribution of the MCs before and after hydrolysis. Electrospray and matrix assisted laser desorption/ionization (ESI and MALDI) in combination with various MS analyzers were compared with respect to quantification of the degradation products directly and after perdeuteromethylation. Methyl group distribution in the oligomeric fractions and the average DS/DP were calculated from ESI mass spectra. With help of the reference analysis, patterns could be corrected for the unspecific contribution of end groups. By labelling and ESI-MSn, our knowledge about the tolerance of the enzyme's sub-sites with respect to the number of methyl groups could be improved. A novel standard addition method in combination with electrospray ionization ion trap mass spectrometry (ESI-IT MS) was used to determine the amount of formed oligomers. 相似文献
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用新的非水溶剂体系制备含磷纤维素衍生物尤田耙,张兴元,沈晓煊,郭荷民,胡小铭(中国科学技术大学化学系合肥230026)关键词非水溶剂,含磷纤维素衍生物,合成近年合成的一些纤维素衍生物被用作不对称合成的手性催化剂配体[1]、拆分光学异构体的色谱手性固定... 相似文献
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纤维素及其衍生物液晶研究新进展 总被引:3,自引:0,他引:3
本文全面地综述了纤维素及其衍生物溶致性液晶和热致性液晶的形成, 液晶性与大分子链结构, 以及具有胆甾型液晶相结构的纤维素衍生物复合材料等方面的最新研究进展。 相似文献
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JinShengZHAO ZhenYuYANG YiHeZHANG ZhengYuYANG 《中国化学快报》2004,15(11):1361-1364
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. 相似文献
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Enzymes are versatile biocatalysts and find increasing applications in many areas. The major advantages of using enzymes in biocatalytic transformations are their chemo‐, regio‐, and stereospecificity, as well as the mild reaction conditions that can be used. However, even when an enzyme is identified as being useful for a given reaction, its application is often hampered by its lack of long‐term stability under process conditions, and also by difficulties in recovery and recycling. For ease of application and stabilization purposes, enzymes are often immobilized on solid supports. Among support matrices, hydrophobic biomaterials have been extensively used as supports for enzyme immobilization because the hydrophobic interactions not only can effectively increase the amount of enzyme immobilization, but also exhibit higher activity and retention of activity compared with hydrophilic supports. On the other hand, polysiloxane can evidently increase the amount of enzyme immobilization because of its hydrophobicity and strong affinity with enzyme. Therefore, this research details the first preparation and use of a hydrophobic polysiloxane support for enzyme immobilization in which the structural and functional characteristics of new supports have been investigated by using glucose oxidase (GOD) and a simple Fenton's assay method, and extremely interesting features were revealed. The results showed that the amount of GOD immobilization and the stability of GOD loaded, which are fundamental properties for enzyme separation and purification, can be significantly improved by adsorption. Moreover, the results indicated that hydrophobic polysiloxane supports can effectively increase the enzymatic affinity and durability of GOD, and decrease the rate of GOD desorbed.
9.
纤维素类手性固定相及高效液相色谱-旋光仪联用技术的研究 总被引:2,自引:0,他引:2
合成了3种纤维素衍生物并分别填充分析型色谱柱,研究了不同的涂敷条件对柱效的影响以及色谱柱的稳定性,对外消旋化合物进行了手性拆分。实现了高效液相色谱-旋光仪的联用,获得了在线旋光曲线。 相似文献
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静电纺丝是一种简单有效的制备聚合物纳米纤维的技术,在组织工程、药物控释和传感器等方面具有广泛的应用。采用静电纺丝技术制备得到的纳米纤维膜具有比表面积大、孔隙率高和易于分离回收等优点,可以作为一种优良的酶固定化载体,目前在酶固定化领域受到了广泛的关注。本文综述了近年来静电纺丝纳米纤维膜固定化酶的研究进展,在阐述静电纺丝纳米纤维膜制备技术的基础上,详细介绍了纳米纤维膜表面担载法和包埋法固定化酶的原理和方法,分析了不同固定化方法的优缺点,并讨论了静电纺丝纳米纤维膜固定化酶的应用前景,对静电纺丝纳米纤维膜固定化酶的发展方向进行了展望。 相似文献
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《Analytical letters》2012,45(1):173-182
Abstract In this work, we present the first separation of enantiomers in gas chromatography (GC) using a fused‐silica capillary column containing cellulose triacetate, cellulose triphenylcarbamate, or cellulose tris(3,5‐dimethylphenylcarbamate) as the new chiral stationary phase. The separated solutes included alcohols, amine, ketone, ether, ester, and amino acid. Their column efficiency, polarity, and chiral selectivity were studied. The retention mechanism was discussed. The results showed that those derivatives had relatively high chiral recognition abilities and can be used as the chiral stationary phases in GC. 相似文献
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Novel environmentally-friendly corrosion inhibitors based on primary aminated modified cellulose (PAC) containing nano-oxide of some metals (MONPs), for instance iron oxide nanoparticles (Fe3O4NPs), copper oxide nanoparticles (CuONPs), and nickel oxide nanoparticles (NiONPs), were successfully synthesized. The as-prepared PAC/MONPs nanocomposites were categorized using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and selected area diffraction pattern (SAED) techniques. The data from spectroscopy indicated that successful formation of PAC/MONPs nanocomposites, as well as the TEM images, declared the synthesized PAC/Fe3O4NPs, PAC/CuONPs, and PAC/NiONPs with regular distribution with particle size diameters of 10, 23 and 43 nm, respectively. The protection performance of the as-prepared PAC and PAC/MONPs nanocomposites on the corrosion of C-steel in molar HCl was studied by the electrochemical and weight-loss approaches. The outcomes confirmed that the protection power increased with a rise in the [inhibitor]. The protection efficiency reached 88.1, 93.2, 96.1 and 98.6% with 250 ppm of PAC/CuONP, PAC/Fe3O4NPs, and PAC/NiONPs, respectively. PAC and all PAC/MONPs nanocomposites worked as mixed-kind inhibitors and their adsorption on the C-steel interface followed the isotherm Langmuir model. The findings were reinforced by FT-IR, FE-SEM and EDX analyses. 相似文献
14.
Akmal M. Asrorov Bahtiyor Muhitdinov Bin Tu Sharafitdin Mirzaakhmedov Huiyuan Wang Yongzhuo Huang 《Molecules (Basel, Switzerland)》2022,27(12)
Cancer is one of the most serious human diseases, causing millions of deaths worldwide annually, and, therefore, it is one of the most investigated research disciplines. Developing efficient anticancer tools includes studying the effects of different natural enzymes of plant and microbial origin on tumor cells. The development of various smart delivery systems based on enzyme drugs has been conducted for more than two decades. Some of these delivery systems have been developed to the point that they have reached clinical stages, and a few have even found application in selected cancer treatments. Various biological, chemical, and physical approaches have been utilized to enhance their efficiencies by improving their delivery and targeting. In this paper, we review advanced delivery systems for enzyme drugs for use in cancer therapy. Their structure-based functions, mechanisms of action, fused forms with other peptides in terms of targeting and penetration, and other main results from in vivo and clinical studies of these advanced delivery systems are highlighted. 相似文献
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Encapsulation within calcium alginate gel capsules was used to produce acoimmobilized enzyme system. Glucose oxidase (GOD)
and catalase (CAT) were chosen as model enzymes. The same values of V
max and K
mapp
for the GOD encapsulated system and for the GOD-CAT coencapsulated system were calculated. When gel beads and capsules were
compared, the same catalyst deactivation sequence for the two enzymes was observed. However, when capsules were employed as
immobilization support, GOD efficiencies were higher than for the gel beads. These results were explained in terms of the
structure of the capsules. 相似文献
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液晶纤维素及其衍生物的进展 总被引:6,自引:0,他引:6
本文讨论了纤维素及其衍生物形成液晶态的准则,综述了它们的溶致和热致液晶性能、流变性能、成型加工特性及纤维和薄膜的结构与力学性能,指出了进一步的研究方向。 相似文献
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Tim Liebert 《Macromolecular Symposia》2008,262(1):28-38
The conception and first results for a newly established project at the Center of Excellence for Polysaccharide Research in Jena are described. The work is focused on the investigation of new cellulose solvents and activating agents. Besides the use of a variety of Ionic Liquids it is the interaction of carbohydrates with boric acid and boronic acid, which will be exploited for the regeneration and chemical modification of the biomacromolecule. Two new ILs bearing cellulose activating anions were discovered which can dissolve the polysaccharide. Studies on the dissolution and chemical conversion of cellulose in ILs show the potential for homogeneous reactions but also reveal a number of side reactions especially for acetate containing ILs. In case of boronic acids a covalent binding on the secondary OH functions of glucose and glucose based polymers can be evidenced for the first time at intact molecules. 相似文献
20.
B. Danielsson E. Rieke B. Mattiasson F. Winquist K. Mosbach 《Applied biochemistry and biotechnology》1981,6(3):207-222
A calorimetric assay procedure for the determination of cellobiose has been developed. The cellobiose is hydrolyzed by β-glucosidase
and the glucose formed is measured calorimetrically by an enzyme thermistor containing co-immobilized glucose oxidase and
catalase. The system was optimized with regard to the arrangement of the enzymes, the pH-dependence of the separate enzymic
steps, and of the total system. By placing the β-glucosidase in a precolumn that could be switched in and out of the flow
through the enzyme thermistor, both cellobiose and glucose present in the sample could be determined. The performance with
standard solutions and with crude samples from cellulose degradation experiments was investigated. 相似文献