Surface Modification of Polypropylene Microporous Membrane by Atmospheric-Pressure Plasma Immobilization of N,N-dimethylamino Ethyl Methacrylate

Surface modification of polypropylene microporous membrane （PPMM） was performed by atmospheric pressure dielectric barrier discharge plasma immobilization of N,Ndimethylamino ethyl methacrylate （DMAEMA）. Structural and morphological changes on the membrane surface were characterized by attenuated total reflection-Fourier transform infrared spectroscopy （FT-IR/ATR）, X-ray photoelectron spectroscope （XPS） and field emission scanning electron microscopy （FE-SEM）. Water contact angles of the membrane surfaces were also measured by the sessile drop method. Results reveal that both the plasma-treating conditions and the adsorbed DMAEMA amount have remarkable effects on the immobilization degree of DMAEMA. Peroxide determination by 1,1-diphenyl-2-picrvlhydrazyl （DPPH） method verifies the exsistence of radicals induced by plasma, which activize the immobilization reaction. Pure water contact angle on the membrane surface decreased with the increase of DMAEMA immobilization degree, which indicates an enhanced hydrophilicity for the modified membranes. The effects of immobilization degrees on pure water fluxes were also measured. It is shown that pure water fluxes first increased with immobilization degree and then decreased. Finally, permeation of bovine serum albumin （BSA） and lysozyme solution were measured to evaluate the antifouling property of the DMAEMA-modified membranes, from which it is shown that both hydrophilicity and electrostatic repulsion are beneficial for membrane antifouling.

Photochemical surface modification of poly(arylsulfone) ultrafiltration membrane and covalent immobilization of enzyme

The sensitivity of poly(arylsulfone)(PSf) for UV irradiation in different solvents(water and ethanol) was investigated. It is confirmed that acrylic acid(AA) and acrylamide(AAm) are grafted only onto the surface of the membrane instead of the interior by FTIR and scanning electron microscope(SEM). The membrane performance(Δ J/J 0 and contact angle θ ) after photografting was studied. In the range of conditions used, the grafting yield increases with irradiation time and monomer concentration growing. After photografting and N 3 dimethyl aminopropyl N' ethycarbodiimide hydrochloride(EDC) activation, PSf membrane was immobilized with hydrogen peroxide oxidoreductase, and showed a higher activity than the control membrane.

Immobilization and Properties of Lipase from Candida rugosa on Electrospun Nanofibrous Membranes with Biomimetic Phospholipid Moities

Reported here is a protocol to fabricate a biocatalyst with high enzyme loading and activity retention, from the conjugation of electrospun nanofibrous membrane having biomimetic phospholipid moiety and lipase. To improve the catalytic efficiency and activity of the immobilized enzyme, poly（acrylonitrile-co-2-methacryloyloxyethyl phosphorylcholine）s（PANCMPCs） were, respectively, electrospun into nanofibrous membranes with a mean diameter of 90 nm, as a support for enzyme immobilization. Lipase from Candida rugosa was immobilized on these nanofibrous membranes by adsorption. Properties of immobilized lipase on PANCMPC nanofibrous membranes were compared with those of the lipase immobilized on the polyacrylonitrile（PAN） nanofibrous and sheet membranes, respectively. Effective enzyme loading on the nanofibrous membranes was achieved up to 22.0 mg/g, which was over 10 times that on the sheet membrane. The activity retention of immobilized lipase increased from 56.4% to 76.8% with an increase in phospholipid moiety from 0 to 9.6%（molar fraction） in the nanofibrous membrane. Kinetic parameter Km was also determined for free and immobilized lipase. The Km value of the immobilized lipase on the nanofibrous membrane was obviously lower than that on the sheet membrane. The optimum pH was 7.7 for free lipase, but shifted to 8.3-8.5 for immobilized lipases. The optimum temperature was determined to be 35 ℃ for the free enzyme, but 42-44℃ for the immobilized ones, respectively. In addition, the thermal stability, reusability, and storage stability of the immobilized lipase were obviously improved compared to the free one.

Electrospun Poly(acrylonitrile-co-acrylic acid) Nanofibrous Membranes for Catalase Immobilization:Effect of Porphyrin Filling on the Enzyme Activity

Porphyrin-filled nanofibrous membranes were facilely prepared by electrospinning of the mixtures of poly（acrylonitrile-co-acrylic acid）（PANCAA） and porphyrins. 5,10,15,20-Tetraphenylporphyrin（TPP） and its metal-loderivatives（ZnTPP and CuTPP） were studied as filling mediators for the immobilization of redox enzyme. Results indicate that the introduction of TPP, ZnTPP and CuTPP improves the retention activity of the immobilized catalase. Among these three porphyrins, the ZnTPP-filled PANCAA nanofibrous membrane exhibits an activity retention of 93%, which is an exciting improvement. This improvement is attributed to both the strong catalase-porphyrin affinity and the possible facilitated electron transfer induced by the porphyrin as evidenced by quartz crystal microbalance （QCM） and fluorescence spectroscopy studies.

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

s: Cellulose/cellulose acetate membranes were prepared and functionalized by introducing amino 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 be used in bioassays.

Enrichment and immobilization of macromolecular analytes on a porous membrane utilizing permeation drag

Enrichment and immobilization of analytes by chemical bonding or physical adsorption is typically the first step in many commonly used analytical techniques. In this paper, we discuss a permeation drag based technique as an alternative approach for carrying out location-specific immobilization of macro- molecular analytes. Fluorescein isothiocyanate （FITC） labeled macromolecules and their complexes were enriched near the surface of ultrafiltration membranes and detected by direct visual observation and fluorescence imaging. The level of macromolecule enrichment at the immobilization sites could be controlled by manipulating the filtration rate and thereby the magnitude of permeation drag. Higher enrichment as indicated by higher fluorescence intensity was observed at higher filtration rates. Also, larger macromolecules were more easily enriched. The feasibility of using this technique for detecting immunocomplexes was demonstrated by carrying out experiments with FITC labeled bovine serum al- bumin （FITC-BSA） and its corresponding antibody. This permeation drag based enrichment technique could potentially be developed further to suit a range of analytical applications involving more sophis- ticated detection methods.

Covalent Immobilization of Lipase on Poly(acrylonitrile-co-maleic acid) Ultrafiltration Hollow Fiber Membrane

Lipase from Candida rugosa was covalently immobilized on the surface of an uhrafihration hollow fiber membrane fabricated from poly （ acrylonitrile-co-maleic acid） （ PANCMA ） in which the carboxyl groups were activated with 1-ethyl-3-（ dimethylaminopropyl ） carbodiimide hydrochloride （ EDC ） and dicyclohexyl carbodiimide （ DCC ）/ N-hydroxyl succinimide（NHS）, respectively. The properties of the immobilized lipase were assayed and compared with those of the free enzyme. The maximum activities were observed in a relatively broader pH value range at high temperatures for the immobilized lipase compared to the free one. It was also found that the thermal and pH stabilities of lipase were improved upon immobilization and at 50 ℃ the thermal inactivation rate constant values are 2. 1 × 10^ -2 for the free lipase, 3.2 × 10^-3 for the immobilized lipase on the EDC-activated PANCMA membrane and 3.5 × 10^-3 for the immobilized lipase on the DCC/NHS-activated PANCMA membrane, respectively.

Specificity Screening of Potential Active Components from Moutan Cortex for Rat Mesangial Cells HBZY-1 by Cell Membrane Immobilized Chromatography

Moutan Cortex (MC) has been demonstrated to have an inhibitive effect on inflammation and oxidative stress responses in mesangial cells in our previous study. However, little is known about the components of MC contributing to this benefit. In the present study, cell membrane immobilized chromatography (CMC), a fast and useful method, was presented for screening potential active components of MC. HBZY-1 cells were incubated with MC (200 μg/mL) at the optimal incubation time (90 min). HPLC-DAD analysis and LC/ESI/MS/MS were performed to distinguish the active components and identify its structural ion fragments. The results showed that eight components binding to HBZY-1 cells were mudanoside B, paeoniflorin sulfonate, paeoniflorin, tetragalloyl glucose (isomeride), hexagalloyl glucose, mudanopiside A, and paeonol. In conclusion, our established CMC might be a useful method for screening potential active components in complicated traditional Chinese medicines. These components might be associated with the efficacy of MC on prevention and treatment of diabetic nephropathy.

Evaluation of Several Procedures for Immobilizing Cholesterol Oxidase Based on Cellulose Acetate Membrane

Immobilized cholesterol oxidase (COD) membrane with higher catalytic activity is important for biosensor. In this paper, several procedures for immobilizing COD based on cellulose acetate (CA) membrane are studied. Reasons causing different catalytic activities are also discussed.

Characterization of cellulose acetate micropore membrane immobilized acylase Ⅰ

This paper describes an innovative method for the immobilization of acylase I, which was entrapped into the CA-CTA micropore membrane. The most suitable casting solutions proportion for immobilizing the enzyme was obtained through orthogonal experiment. Properties of the enzyme membrane were investigated and compared with those of free enzyme and blank membrane. The thermal stability and pH stability of the enzyme inside the membrane were changed by immobilization. The optimum pH was found to be 6.0, which changes 1.0 unit compared with that of free acylase I. The optimum temperature was found to be about 90℃, which is higher than that of free acylase I (60℃). Experimental results showed that immobilization had effects on the kinetic parameters of acylase I.

Research and Application Progress of Silk Fibroin Membranes

This paper mainly introduced the preparation of silk fibroin membranes and their structural change characteristics.Silk fibroin membranes can be used as tissue engineering materials,enzyme-immobilizing membranes,biosensors and drug controlled-release membranes and other different materials.They have excellent characteristics such as non-toxic,non-polluting and degradable,and thus have broad application prospects.

Interactions Mode of Amphoteric Molecules with Ordered Phospholipid Membrane

Aim To explore interaction mode between amphoteric molecules with the orderedphospholipid membrane. Methods Membrane interactions were determined by immobilized artificialmembrane (IAM) chromatography and solutes' hydrophobicity was measured by n-octanol/buffer system.Results The ampholytes, similar to bases, generally exhibited higher membrane affinity than expectedfrom their hydrophobicity, resulting from the attractive polar interaction with phospholipidmembrane. Furthermore, the strength of additional polar interaction with membrane (Δlg k_(IAM)) wasthen calculated. The Δlg k_(IAM) values were far greater for bases and ampholytes ranging from0.50 - 1.39, than those for acids and neutrals with the scope from - 0.55 - 0.44. ConclusionConsidering the microspecies distribution of amphoteric molecules, it was assumed that not onlyneutral and positive but also zwitterionic microspecies are capable of partitioning into orderedamphoteric lipid membrane with complementarily conformational and energetically favorableinteractions.

Fabricating biopolymer-inorganic hybrid microspheres for enzyme immobilization:Connect membrane emulsification with biomimetic mineralization

The organic-inorganic hybrid composites displayed great potential for biotechnological and biomedical application.In this research,a gelatin/alginate/silica hybrid microsphere was developed by a synergy of membrane emulsification process and biomimetic mineralization method.The gelatin was mixed and complexed with alginate solutions(water phase).The water phase was extruded through a Shirasu Porous Glass(SPG)membrane,and then was crosslinked,which formed gelatin/alginate microspheres.The biomimetic mineralization was occurred in situ by immersing gelatin/alginate complex in a Na_(2)SiO_(3) solution,while silica was formed around the organic microspheres,resulting in the final gelatin/alginate/silica hybrid microspheres.These microspheres were characterized by SEM,TEM,EDS,TGA/DTA,and DSC.The hybrid microcapsules present a more than 40%mass fraction of the inorganic component,and displayed superior swelling resistance to biopolymer complex microspheres.Glycerol dehydrogenase(GlyDH)was immobilized in the obtained novel gelatin/alginate-silica hybrid microspheres as the model enzyme.Due to the protective effect of carriers,the pH tolerance stability,storage and recycling stability of the immobilized GlyDH were all improved in comparison with free GlyDH.

Enzyme immobilization on a pH-responsive porous polymer membrane for enzymatic kinetics study

Immobilization of enzymes onto carriers is a rapidly growing research area aimed at increasing the stability,reusability and enzymolysis efficiency of free enzymes.In this work,the role of phaseseparation and a pH-responsive"hairy"brush,which greatly affected the topography of porous polymer membrane enzyme reactors(PMER),was explored.The porous polymer membrane was fabricated by phase-separation of poly(styrene-co-maleic anhydride-acrylic acid)and poly(styrene-ethylene glycol).Notably,the topography and pores size of the PMER could be controlled by phase-separation and a pHresponsive"hairy"brush.For evaluating the enzymolysis efficiency of D-amino acid oxidase(DAAO)immobilized carrier(DAAO@PMER),a chiral ligand exchange capillary electrophoresis method was developed with D-methionine as the substrate.The DAAO@PMER showed good reusability and stability after five continuous runs.Notably,comparing with free DAAO in solution,the DAAO@PMER exhibited a17.7-folds increase in catalytic velocity,which was attributed to its tailorable topography and pHresponsive property.The poly(acrylic acid)moiety of poly(styrene-co-maleic anhydride-acrylic acid)as the pH-responsive"hairy"brush generated topography changing domains upon adjusting the buffer pH,which enable the enzymolysis efficiency of DAAO@PMER to be tuned based upon the well-defined architectures of the PMER.This approach demonstrated that the topographical changes formed by phaseseparation and the pH-responsive"hairy"brush indeed made the proposed porous polymer membrane as suitable supports for enzyme immobilization and fitting for enzymolysis applications,achieving high catalytic performance.

聚丙烯二氧化钛负载膜固定化农药降解酶的研究

利用聚丙烯负载二氧化钛膜固定农药降解酶(EC3.1.8.2),研究了酶固定化的条件,选择农药甲基对硫磷进行了降解试验。结果表明,酶固定化最佳时间为1.5h,最适固定温度为20℃,最佳固定化酶液浓度为1.6mg/mL。吸附农药降解酶的聚丙烯负载二氧化钛酶膜,通过与游离酶的比较,固定化酶最适反应温度有所偏移,提高了5℃,酶降解农药的最适pH值为8.5,对农药甲基对硫磷的降解率30min内达到70%以上,并且固定后的二氧化钛酶膜具有良好的稳定性。

酶的膜固定化及其应用的研究进展

酶的膜固定化作为一种重要的生物技术已经得到了广泛的应用.文章在总结传统的酶膜固定化方法的基础上,对这一领域新的进展,如光、辐射等物理技术的应用、定点固定化技术以及多酶系统共固定等作了相应的综述.此外,还对酶膜生物反应器,尤其是其在对外消旋混合物手性拆分以及污水处理方面的应用作了简要的介绍.

新型固定化细胞膜反应器脱氮研究

研究了一种新型的废水生物脱氮反应器 ,即利用固定化细胞膜将反应器一隔为二 ,膜的一侧与好氧的氨氮废水接触 ,另一侧与缺氧的乙醇水溶液 (反硝化碳源 )接触 .固定于膜中的硝化细菌将氨氮氧化成亚硝氮和硝氮 ,随即被同一膜中的反硝化细菌还原成氮气 .硝化细菌和反硝化细菌混合固定于膜内时的氨氧化速率约为硝化细菌单独固定时的 2倍 .未发现碳源重复利用对脱氮过程产生不利影响 .此新型反应器可以稳定运行 5

明胶膜固定化脲酶的制备及性质

以明胶为载体,戊二醛为交联剂,采用包埋-交联联用法制备了明胶膜固定化脲酶,其酶活力为6 07U/g载体,酶活力收率为66 1%。最优固定化条件是包酶量为10mg酶/g明胶,ρ(明胶)=100g/L,φ(戊二醛)=0 5%。研究了固定化酶的性质,并与游离酶作了比较,游离酶的最适pH=7 0,固定化酶的最适pH=6 5;游离酶的最适温度为60℃,固定化酶的最适温度升至70℃;固定化酶与游离酶的米氏常数Km分别为11 7mM和12 4mM;固定化酶在80℃下180min仍保留初始活力的10%,而游离酶几乎完全失活。固定化酶重复使用20次其活力仅下降15%,4℃下贮存35d后仍保持初始活力的55%。

醋酸纤维素膜固定化脲酶的研究

酶固定膜反应器兼具有反应和分离两种功能，是酶工程领域中较活跃的研究课题［１～３］．随着酶固定化技术和水平的提高，各种固定化酶生物反应器不断涌现，其中以采用固定化脲酶技术制作的人工肾最为成功［３］．在国内，采用分子筛和聚乙烯醇高含水胶作载体固定化脲酶已...

醋酸纤维素固定化酰化酶膜的研究

采用正交实验法 ,考察了铸膜液配比对醋酸纤维素固定化氨基酰化酶微孔滤膜的影响 ,对酶膜的泡点压力、孔径、孔隙率及透水速率等性能进行了表征 .结果表明 ,铸膜液组合最佳时 ,酶相对活力产率高达 98 2 % ,酶膜的透水率适当 ,重复使用 10次后仍保留原活力的 79 7% 。