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膜材料的亲疏水性对固定化脂肪酶的影响 总被引:5,自引:0,他引:5
用吸附法固定脂肪酶时,膜材料的亲疏水性对固定化酶的量、比活力和活力稳定性等有很大影响.今以柱状假丝酵母脂肪酶和猪胰脂肪酶为研究对象,选取了8种亲疏水性不同的膜材料(醋酸纤维素、聚丙烯腈、聚酰胺、聚砜、聚醚砜、聚偏二氟乙烯、聚丙烯和聚四氟乙烯)作为固定化载体,用吸附法制备了固定化脂肪酶膜.研究结果表明,强疏水性聚四氟乙烯和聚丙烯膜对两种酶的吸附量都比较大,且固定化酶的比活力和活力回收率比较高,聚四氟乙烯固定化柱状假丝酵母酶比游离态酶的半衰期提高了6倍以上.强亲水性醋酸纤维素膜对猪胰脂肪酶的吸附量比聚四氟乙烯高,但是固定化酶的比活力、活力回收率比强疏水性膜低,而接触角在40°~50°的聚酰胺膜和聚砜膜的吸附量最小.因此吸附法制备固定化脂肪酶膜,选择聚丙烯膜和聚四氟乙烯膜是合适的,制备的优化条件为吸附温度25℃,酶溶液的pH为7.5,吸附时间10 h. 相似文献
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《化工中间体》2016,(3)
应用层层自组装技术(LBL)构筑聚电解质多层膜的过程中,组装溶液的离子强度对组装过程有特殊影响。采用紫外分光光度计与椭偏仪同时监测聚电解质沉积时间,聚阳离子(PDDA)浓度,特别是添加氯化钠(NaCl)对聚电解质成膜的影响。聚电解质分别沉积在石英基底和硅基底上,聚电解质膜厚度与聚电解质层数呈现良好的线性关系;随着聚电解质沉积时间的增加,聚电解质膜厚度逐渐增加,沉积时间为10min时聚电解质膜厚度最大;聚电解质膜的厚度随着PDDA浓度的增加呈现增长趋势;聚电解质溶液中加入NaCl,组装层数不大于10层时,聚电解质膜厚度随着NaCl浓度的增加而呈现线性增长。 相似文献
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本文通过调节环境pH酸碱度改变聚电解质膜中氨基基团的键合状态,以控制聚电解质膜表面金纳米粒子的原位还原与自组装过程中的聚集行为,发现当聚电解质膜经pH为5.40的去离子水处理后可在其表面制备出片状金纳米结构;经pH为0.65的强酸溶液处理后,可在膜表面制备出树枝状的金纳米结构,且尺寸比pH为5.40条件下增大一倍;经pH为12.77的强碱溶液处理后,金纳米粒子的聚集状态发生改变,形成了球形纳米结构;对金纳米粒子形貌的调控机理进行了初步探讨. 相似文献
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以静电纺丝法制备的PAN纳米纤维多孔膜为基膜,以层层自组装成膜技术制备的壳聚糖-海藻酸钠聚电解质涂层为表面选择性涂层,成功制备了聚电解质涂层/纳米纤维膜复合滤膜。用扫描电镜(SEM)对复合膜的微观形态进行表征。在操作压力为0.7MPa的条件下,分别过滤纯水以及质量浓度为1000mg/L的NaCl和500mg/L的MgSO4溶液,测试结果表明:盐离子截留率随聚电解质涂层层数的增加而增加,但同时复合膜的水通量随之明显降低。当聚电解质涂层层数为10时,水通量均在18L/m·2h左右,对MgSO4截留率为64.22%,对NaCl截留达到52.45%。 相似文献
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Yulei Tai Li Wang Jingmin Gao Weihong Tao Jia Huo Lirong Yang 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(1):213-222
Magnetic porous hydrophobic microspheres were prepared by modified suspension copolymerization of methacrylate (MMA) and divinylbenzene
(DVB) in the presence of oleic acid coated magnetite (Fe3O4), and the microspheres were used as biocarrier for the lipase immobilization. The results showed that the magnetic microspheres
possessed spherical shape, core/shell structure, porous structure and high magnetic content, and the size and structure of
magnetic microspheres had no significant changes after enzyme binding. The particle average size of microspheres was 66 μm,
the magnetic content of microspheres was up to 31%, and the magnetization saturation values of the core/shell magnetic microspheres
were measured at 300 K to be 11.02 emu g−1. Lipase was immobilized on the magnetic porous carrier at up to 16.30 mg/g carrier. Activity and enantioselectivity of the
immobilized lipase for the synthesis of R-HMPC acetate were investigated, indicating an interfacial activation of the enzyme
after immobilization. Moreover, the pH dependency and operational stability of the immobilized lipase were studied, and they
possess high stability and can be reused for ten cycles with loss 10% activity. 相似文献
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The synthesis of hollow latex particles through seeded emulsion polymerization involves a series of intricate steps, including the formation of distinct polymer layers with specific properties. Despite extensive research, preserving the desired hollow structure remains challenging due to the unclear role of the encapsulating polymer layers. This study systematically adjusts the glass transition temperature (Tg) of the intermediate layer by varying the butyl acrylate (BA) ratio in the monomer feed mixture. By controlling the reaction temperature during alkali swelling, we explore the critical influence of Tg on hollow latex particle formation from carboxylated core latex particles. To ensure long-term hollow structure retention after drying, a rigid outer layer is polymerized onto the intermediate layer. Surprisingly, higher divinylbenzene (DVB) mass ratios (5.0 and 10.0 wt%) do not result in a highly crosslinked hollow shell due to DVB self-nucleation. This paper emphasizes the importance of precise design parameters for both intermediate and outermost layers in achieving and maintaining hollow latex particle structures. Understanding each layer's role and optimizing their compositions contribute to advancing hollow latex particle synthesis through seeded emulsion polymerization. 相似文献
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开发了以磁性多孔微粒作为载体固定化脂肪酶的方法,进行了载体的FTIR、XRD、SEM、TEM、BET、TGA和VSM等测定与分析,考察了固定化时间、酶载量和缓冲液pH值等因素对固定化酶在有机相中催化烯丙醇酮转酯化反应性能的影响。结果表明,制备的磁性微粒是以Fe3O4为磁核,呈现多孔,比表面积12.16 m2 /g,平均孔径为171.7 nm,磁铁含量38%并为超顺磁性;在酶与载体质量比为1∶1、pH值8.0及固定化时间6 h制得固定化酶的效果最佳,固定化酶的活力回收率可达240%。以其作为载体制备获得固定化酶操作稳定性得到显著提高,重复利用30批次后残余活力为74.5%,而游离酶7批次后仅为37.1%。 相似文献
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Jingshui Xu Yangchuan Ke Qian Zhou Xianglong Hu Zijuan Tan Liyan Yang Youzhi Song Yangyang Zhao Guoliang Zhang 《Polymer Composites》2014,35(6):1104-1116
Effective encapsulation of montmorillonite intermediate particles (I‐MMT) within poly (vinyl acetate‐co‐methyl methacrylate) (PVAMMA) copolymer by in situ suspension polymerization was performed. The I‐MMT encapsulation, layer exfoliation behavior, chemical composition, particle size distribution and thermostability of PVAMMA/I‐MMT nanocomposite microspheres were characterized by electron microscopies, X‐ray diffraction (XRD), laser particle analyzer, and thermogravimetric analysis (TGA). Swelling behaviors of the nanocomposite microspheres in various cationic salt solutions (NaCl and CaCl2) and anionic salt solution (NaCl and Na2SO4) were also investigated. Results showed that the properties of layer dispersion surface and expansion of these nanocomposite microspheres were well achieved. The synthetic yields of the nanocomposites decreased as the I‐MMT loading increased. These nanocomposite microspheres had an average size from 96.8 μm to 138.4 μm with narrow particle size distribution, loose, and porous surface morphology. XRD patterns clearly proved the exfoliation of MMT layers in the copolymer matrix, which was consistent with TEM analysis. These nanocomposite microspheres showed higher negative zeta potential and higher thermal stability than those of the copolymer microspheres, which was due to the layer exfoliations in encapsulated microspheres. These selected microspheres with 10 to 70 μm diameters provided effectively plugging in the micrometer‐sized core channels through deformation and migration process in plugging experiments, which made them be the candidate materials for modifying the porous reservoir to enhance oil recovery in petroleum engineering. POLYM. COMPOS., 35:1104–1116, 2014. © 2013 Society of Plastics Engineers 相似文献
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Arjan P.H. Gelissen Andreas J. Schmid Felix A. Plamper Dmitry V. Pergushov Walter Richtering 《Polymer》2014
A cationic microgel with quaternized amine groups was prepared and used as a soft template for layer-by-layer (LbL) assemblies. The presence of quaternized amine groups inside the microgels was necessary to prevent rearrangements and subsequent bridging between the coated microgels, which were observed for the precursor microgels containing protonated primary amino groups. Sequentially, negatively charged polyelectrolyte poly(sodium styrene sulfonate) (PSS) and positively charged polyelectrolyte poly(diallyldimethylammonium chloride) (PDADMAC) were added to a suspension of quaternized microgels. This leads to an odd-even effect with respect to particle size and surface charge of the formed microgel–polyelectrolyte complexes (MPECs). MPECs with an even number of layers exhibit positive surface charge due to PDADMAC as the outermost layer and are larger compared to complexes with an odd number of layers, which are negatively charged having PSS in the outermost layer. Taking into account previous results (Macromolecules,2009,42, 1229), these observations show that electrostatic interactions are the major force for the odd-even effect in polyelectrolyte multilayers on microgels: the cationic groups of PDADMAC compete with the cationic moieties of the microgel for binding with the sulfonate groups of PSS. Concomitantly, a fluctuating size of the MPECs is induced by an osmotic pressure modulation within the microgel. In contrast, surface tension effects invoked by a possible varying hydrophilicity of the different terminal layers are negligible. 相似文献
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Chularat Iamsamai Apinan Soottitantawat Uracha Ruktanonchai Supot Hannongbua Stephan Thierry Dubas 《Carbon》2011,(6):2039-2045
A simplified method for the surface modification of multiwall carbon nanotubes (MWCNTs) using the layer-by-layer (LbL) technique is proposed. In this approach, the minimum polyelectrolyte content was added to the solution in order to eliminate the tedious centrifugation step. The one pot LbL deposition of poly (diallyldimethylammonium chloride) (PDADMAC), and poly (sodium 4-styrenesulfonate), (PSS) is presented. UV–Vis spectroscopy and zeta potential measurements were used to determine the minimum PDADMAC and PSS concentration needed for the deposition of each polyelectrolyte layer. The deposition cycle was repeated until six layers of PDADMAC/PSS were deposited. The film growth was confirmed by transmission electron microcopy and was found to increase as a function of the number of deposited layers with a final thickness of 18 nm. Evidence of the alternate deposition of oppositely charged polyelectrolytes was further investigated by measurement of the zeta potential values which were found to reverse from positive to negative as a function of the number of deposited layers thus confirming the overcompensation of the surface charge at each adsorption step. This simple method could be useful for the fast preparation of large volumes of MWCNTs solutions in a single batch without the need for centrifugation step. 相似文献
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壳聚糖固化单宁微球的制备及其吸附性能 总被引:3,自引:1,他引:2
5 g单宁酸与10 g壳聚糖微球在100 mL pH=7的溶液中反应6 h,再用0.06 mol/L环氧氯丙烷在pH=10,50℃反应4 h制得壳聚糖固化单宁微球,每克壳聚糖微球固载单宁量为0.27 g。采用扫描电镜和红外光谱对微球进行了表征,考察了微球的溶胀性能及对金属离子的吸附性能。研究表明,通过此法制得的壳聚糖固化单宁微球具有表面粗糙,内部疏松多孔的结构。与壳聚糖微球相比,壳聚糖固化单宁微球在溶液中的溶胀性减小,在pH=5及9时,分别减小了63%和50%。对金属离子的吸附容量增大,对Cd2+的吸附容量从0.6 mmol/g提高到2.2 mmol/g,提高了2.66倍。 相似文献
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Kwinam Park Honghyun Kim Sanjeev Maken Yeounsoo Kim Byoungryul Min Jinwon Park 《Korean Journal of Chemical Engineering》2005,22(3):412-417
The hydrophilic copolymer, polyethylene oxide (PEO) allyl ester-maleic anhydride (MA), copolymer was used to modify the lipase
from Candida rugosa. MA, in a functional group, reacts easily with amino acids of lipase. The degree of modification (DM)
was varied by changing the weight ratio of copolymer to protein of lipase over the range of 10–120 (w/w). The specific activity
decreased as DM increased. At the maximum modification degree of 35%, the modified lipase retained more than 65% of the unmodified
native lipase activity. The modified lipase displayed a high stability of activity against temperature and pH. The remaining
activity of modified lipase was about 2–4 fold of that of native lipase in the severe pH and temperature condition. Finally,
it showed 20% greater reaction of substrate at 10 hr than in the case where native lipase was used. 相似文献
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种子溶胀聚合制备苯乙烯-二乙烯苯多孔交联微球 总被引:6,自引:0,他引:6
以苯乙烯分散聚合制备单分散种子微球(PS),再用超声分散改进的二步种子溶胀聚合制备了聚苯乙烯-二乙烯苯(PSt-DVB)多孔微球。用光学显微镜、扫描电镜(SEM)和比表面积孔径分布测定仪(BET)等对种子微球和多孔微球的表面形貌及孔结构进行了表征。结果表明,随分散介质极性的增大,所得PS种子微球的粒径变小,相对分子质量增大;固定种子微球用量,随着DBP和DVB用量的增加,交联微球比表面积上升、孔径下降。以乙醇为介质制备种子微球,当DBP体积为1.0 mL,DVB体积为8~10 mL时,能够得到4~7μm单分散性良好的多孔PSt-DVB微球。 相似文献
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用作活性物载体聚苯乙烯-二乙烯苯多孔交联微球的悬浮聚合制备及表征 总被引:1,自引:0,他引:1
Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene (ST) with divinylbenzene (DVB) in the presence of toluene, cyclohexanol and heptane as porogenic diluents. The use of ultrasonic dispersion decreases the beads' size and improves the uniformity. The effects of the porogen mixture, DVB content and solvent extraction on the surface performance of the synthesized beads were studied. The microspheres were characterized by scanning electron microscopy (SEM) and BET surface area determination. It was found that a great proportion of the non-solvating porogen increases the pore diameter and the specific surface area. High DVB concentration also results in the great specific surface area and porosity. When the ratio of toluene/cyclohexanol is 1:2, DVB content is at the range of 40%-60% and methylene chloride was used as extractant, the beads with good spherical shape and pore size were obtained. The prepared porous microspheres were applied as active carriers and showed satisfactory slow release effect. Over 10h constantly sustained release was observed in vitro releasing test for hydroquinone-loaded microspheres. Great surface area promoted high concentration of released hydroquinone. 相似文献