An ion-imprinted polymer supported by attapulgite with a chitosan incorporated sol-gel process for selective separation of Ce(Ⅲ)

The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the synthesis of a new attapulgitesupported polymer for selective separation of Ce（III） from aqueous solution. The imprinting mechanism of prepared ion-imprinted polymer were discussed with the Characteristics of FT-IR and SEM. Results from the experiments of adsorption capacity and selectivity suggested that ion-imprinted polymer offered a fast kinetics for the adsorption of Ce（III） under the optimum conditions. Its maximum adsorption capacity was 38.02 mg/g, and the selective recognition towards Ce（III） was much higher than that of the non-imprinted polymer and attapulgite. The prepared functional polymer was shown to be promising for selective separation and enrichment of trace Ce（III） in environmental samples. ？2009 Yong Sheng Yan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Preparation of Magnetic Chitosan Nanoparticles and Immobilization of Laccase

The magnetic chitosan nanoparticles were prepared by reversed-phase suspension method using Span-80 as an emulsifier, glutaraldehyde as cross-linking reagent. And the nanoparticles were characterized by TEM, FT-IR and hysteresis loop. The results show that the nanoparticles are spherical and almost superparamagnetic. The laccase was immobilized on nanoparticles by adsorption and subsequently by cross-linking with glutaraldehyde. The immobilization conditions and charac-terizations of the immobilized laccase were investigated. The optimal immobilization conditions were as follows： 10 mL of phosphate buffer （0.1 M, pH 7.0） containing 50 mg of magnetic chitosan nanoparticles, 1.0 mg·mL-1 of laccase and 1% （v/v） glutaraldehyde, immobilization temperature of 4 ℃ and immobilization time of 4 h. The immobilized laccase exhibited an appreciable catalytic capability （480 units·g-1 support） and had good storage stability and operation stability. The Km of immobilized and free laccase for ABTS were 140.6 and 31.1 μM in phosphate buffer （0.1 M, pH 3.0） at 37 ℃, respectively. The immobilized laccase is a good candidate for the research and development of biosensors based on laccase catalysis.

Immobilization of microorganisms using carrageenan gels coated with chitosan and application to biodegradation of 4-chlorophenol

A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanical strength and the thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.

Preparation, Characterization and Drug-Release Behaviors of Crosslinked Chitosan/Attapulgite Hybrid Microspheres by a Facile Spray-Drying Technique

A series of chitosan/attapulgite (CTS/APT) hybrid microspheres were prepared by a facile spray-drying technique. The developed hybrid microspheres were characterized by Fourier transform infrared spectra (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and the zeta potential. The encapsulation efficiency and in vitro controlled release properties of the microspheres for drug were evaluated using diclofenac sodium (DS) as a model drug. Results indicated that the introduction of APT into crosslinked CTS microspheres can achieve narrow size distribution and make them more uniform. The isoelectric point of the microspheres increased from 8.14 to 9.18 with increasing the content of APT to 10 wt.%. DS loaded in hybrid microspheres is hardly released in simulated gastric fluid, but quickly released in simulated intestinal fluid. The electrostatic interaction between hybrid microspheres and DS can improve the encapsulation efficiency and controlled release behavior of CTS/APT microspheres, and the release mechanism fits Fickian diffusion.

Immobilization of His-Tagged Proteins on Various Solid Surfaces Using NTA-Modified Chitosan

Continued advancement of protein array, bioelectrode, and biosensor technologies will necessitate development of methods that allow for increased protein immobilization capacity and more control over protein orientation. Toward these ends, we developed a method involving modification of chitosan with nitrilotriacetic acid (NTA) to achieve immobilization of a larger amount of His-tagged protein than is possible with current methods. The immobilization capacity of our method was evaluated using His-tagged GFP (Green Fluorescent Protein) as a model protein. The average immobilization density on modified glass was about 32 ng/mm2. Our method is suitable for use on a variety of solid surfaces, including glassy carbon, silicon wafers, polycarbonate, and beaten gold.

Development of Urease Immobilization Using Poly（acrylonitrile）/Chitosan Composite Materials

PANCHI （poly（acrylonitrile）/chitosan） composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of poly（acrylonitrile） and PANCHI membranes were determined by SEM analyses It was found that the membrane coated with 1.0% chitosan shows the maximum reduced pore size. The amounts of the functional groups and the degree of hydrophilicity of PANCHI composite membranes were determined. Urease was covalently immobilized onto all kinds of PANCHI membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity （92.96%） was measured for urease bound to PANCHI （1%） membranes. The basic characteristics of optimum conditions （pH and temperature）, heat inactivation and storage stability of immobilized urease were determined. Immobilization improved the thermal, pH and storage stability of the enzyme. The obtained results show that the poly（acrylonitrile）/chitosan composite materials are suitable for urease immobilization.

Immobilized chitosan as a selective absorbent for the nickel removal in water sample

Method for preparation of chitosan immobilized on silica gel(CTS silica) was described. The CTS silica was used as absorbent for the absorption of nickel in water. The results showed that this absorbent had relatively high selectivity and strong affinity to nickel. The maximum absorption capacity for nickel can reach 667 mg/g of chitosan. Factors that affect the absorption capacity, such as pH, ion strength and the presence of calcium, EDTA and the mechanism of absorption were discussed in detail. The absorbent can be regenerated with acid and reused for several times. The recovery rate for nickel can reach 99 99%. This absorbent filled in a column can be used in nickel removal from wastewater and drinking water.

Preparation of Glutaraldehyde Cross-Linked Chitosan Beads Under Microwave Irradiation and Properties of Urease Immobilized onto the Beads

The glutaraldehyde cross-linked chitosan beads were prepared under microwave irradiation and urease was immobilized onto the beads. The activity and the yield of enzyme activity of the immobilized urease were 10.83 U/g carrier and 47.700, respectively. The optimum conditions of immobilization were 100 of glutaraldehyde volume fraction, 10 mg/g of urease/beads weight ratio, 24 h of the processing time and pH 6.5 of the reaction medium for immobilization. The properties of the immobilized urease were investigated and compared with those of the free enzyme. The optimum pH values were 6.5 and 7.0 for the immobilized and free urease, respectively. The optimum temperature was 60 ℃ for the free urease, while it shifted to 65 ℃ for the immobilized enzyme. The Michaelis constant Km was 9.1 mmol/L for the immobilized and 12.5 mmol/L for the free urease. The immobilized urease retained 4000 of its initial enzyme activity even after 10 repeated uses. The immobilized urease stored at 4 ℃ retained 4600 of its initial activity even after 35 d.

Culture of yeast cells immobilized by alginate-chitosan microcapsules in aqueous-organic solvent biphasic system

Immobilization biocatalysis is a potential technology to improve the activity and stability of biocatalysts in nonaqueous systems for efficient industrial production.Alginate-chitosan(AC)microcapsules were prepared as immobilization carriers by emulsifi cation-internal gelation and complexation reaction,and their contribution on facilitating the growth and metabolism of yeast cells were testifi ed successfully in culture medium-solvent biphasic systems.The cell growth in AC microcapsules is superior to that in alginate beads,and the cells in both immobilization carriers maintain much higher activity than free cells,which demonstrates AC microcapsules can confer yeast cells the ability to resist the adverse effect of solvent.Moreover,the performance of AC microcapsules in biphasic systems could be improved by adjusting the formation of outer polyelectrolyte complex(PEC)membrane to promote the cell growth and metabolic ability under the balance of resisting solvent toxicity and permitting substrate diffusion.Therefore,these findings are quite valuable for applying AC microcapsules as novel immobilization carriers to realize the biotransformation of value-added products in aqueous-solvent biphasic systems.

Chitosan-immobilized Palladium Complex: a Green and Highly Active Heterogeneous Catalyst for Heck Reaction

A green heterogeneous catalyst for Heck reaction-chitosan-immobilized palladium complex was prepared. The catalyst exhibits high activity and stereoselectivity under the moderate reaction conditions. The catalyst can be separated easily from the reaction mixture and reused after washing. Under the suitable reaction conditions, the cross-coupling of iodobenzene (ArI) with acrylic acid (AA) or acrylate can be achieved 93.3% or 99% yield of trans-cinnamic acid or trans-cinnamic ester.

PREPARATION OF SURFACE ION-IMPRINTED ATTAPULGITE-SUPPORTED POLYMER AND ITS ADSORPTION BEHAVIORS OF Sr(II)

The surface ion-imprinting concept and chitosan incorporated sol-gel process were applied to the preparation of a new attapulgite-supported organic-inorganic hybrid polymer for selective separation of Sr(II) from aqueous solution. The prepared polymer was characterized with SEM, IR and XRD. The results showed that as a sorbent, it had good configuration and binding sites. Its adsorption behaviors for Sr(II) was investigated by FAAS and ICP-AES. The effects on adsorption capacities, including pH, quiescent time, and adsorbent amount were discussed, and the adsorption isothermal curve was obtained. Then the Kd a parameter estimating relative adsorbability, was conducted to study the selectivity towards Sr(II) of the prepared polymer. Under the optimum conditions, the ion-imprinted polymer offered a fast kinetics for the adsorption of Sr(II) and the maximum capacity was 12.9mg/g. The Kd and K parameters estimating relative adsorbability towards target ion, suggested that selective recognition of the ion-imprinted polymer towards Sr(II) was much higher than that of the non-imprinted polymer and attapulgite. Furthermore, the ion-imprinted polymer is of great regeneration capacity. The prepared functional polymer was shown to be promising for selective preseparation and enrichment of trace Sr(II) in environmental samples.

Preparation and Properties of Urease Immobilized onto Glutaraldehyde Cross-linked Chitosan Beads

Urease was immobilized onto the glutaraldehyde cross-linked chitosan beads that were prepared under microwave irradiation. The activity and the yield of activity of immobilized urease was 10.83 U/g B and 47.7%, respectively. The conditions of urease immobilization were optimized. The properties of the immobilized urease were investigated and compared with that of the free enzyme.

Kinetic of Adsorption of Urea Nitrogen onto Chitosan Coated Dialdehyde Cellulose under Catalysis of Immobilized Urease

The adsorption of urea nitrogen onto chitosan coated dialdehyde cellulose (CDAC) under catalysis of immobilized urease in gelatin membrane (IE) was studied in batch system. The pseudo first-order and second-order kinetic models were used to describe the kinetic data, and the rate constants were evaluated. The experimental data fitted well to the second-order kinetic model.

Preparation and properties of pectinase immobilized on chitosan support

Pectinase was immobilized onto chitosan support itsing glutaraldehyde as a coupling agent to obtain high activity and stability of pectinase.x A maximum residual activity of 55% was obtained with 0.4 mg proteirdg chitosan （w/w）, 5% （v/v） g/utara/dehyde, and 4℃ for the crosslinking reaction. The optimal pH and temperature for pectinase activity changed from 3.0 and 40℃ to 3.5 and 50℃, respectively, after immobilization The immobilized enzyme exhibited higher stability under varying conditions of pH and temperature and better reusability than the free enzyme.

用CHITOSAN固定化青霉素酰化酶

本文报道以Chitosan为载体制备固定化青霉素酰化酶的研究结果。1.4％ Chitosan醋酸溶液先用12.5％戊二醛交联,洗涤,研磨,得颗粒。再用1.5％pH5.5和1.5％pH8.5多聚磷酸处理,得机械强度良好的载体。此载体先后经0.5％戊二醛和对甲苯磺酰氯双活化后,再与青霉素酰化酶偶联。所得固定化酶的活力达20.8u/g。固定化青霉素酰化酶的反应最适温度略高于游离酶,最适pH略低于游离酶;其Km值基本接近游离酶。固定化酶经反复使用,活力基本不变。

PREPARATION OF CHITOSAN COATED METAL AFFINITY CHROMATOGRAPHY ADSORBENT

A new and an inexpensive adsorbent of chitosan coated silica for immobilized metal affinity chromatography (IMIC) was studied. After a double coating, the chitosan coated on silica beads could be up to 53. 4 mg/g silica beads.When pH＞3. 8, the metal ligand Cu2+ was chelated on the coated chitosan witha bound capacity of 14. 6 mg/g chitosan without introducing iminodiacetic acid(IDA).

β-半乳糖苷酶的固定化及其合成低聚半乳糖研究

选用壳聚糖、海藻酸钠、海藻酸钠/明胶、海藻酸钠/羧甲基纤维素为固定化载体材料,探究β-半乳糖苷酶的固定化方法,并将获得的适宜固定化酶应用于合成低聚半乳糖(galacto-oligosaccharide,GOS)。结果表明,较优固定化载体为壳聚糖,β-半乳糖苷酶的优化固定化条件为壳聚糖质量浓度0.03 g/mL,静置时间2 h,戊二醛体积分数2%,交联时间3 h,吸附时间12 h,固定化温度60℃,加酶量0.4 mg/g(以壳聚糖微球质量计)。与游离酶相比,固定化酶的耐酸、碱、热的稳定性显著提升。进一步利用壳聚糖固定化β-半乳糖苷酶合成GOS,确定了优化反应条件:加酶量为2 U/mL,pH值为6.0,反应温度为50℃,初始乳糖质量浓度为500 g/L,反应时间为14 h。此条件下GOS产率可达到52.61%,高于已报道的GOS产率(25.1%~46.0%),且产物中聚合度大于等于3的GOS含量为37.07%。固定化酶重复使用5次后,产GOS活性仍保留了97.21%,研究获得的壳聚糖固定化β-半乳糖苷酶在GOS合成领域具有良好的应用前景。

一种高耐热乳糖酶的异源表达、固定化及酶学性质研究

乳糖酶在乳制品生产中具有重要作用,但是目前商用的乳糖酶耐热性低,可重复利用率差。为了解决以上问题,该实验用枯草芽孢杆菌WB800异源表达了激烈热球菌(Pyrococcus furiosus)来源的β-半乳糖苷酶(β-galactosidase,BgaS)。该酶最适温度为90℃,最适pH值为7,具有良好的应用潜力。为了提高该乳糖酶的重复利用率,该实验用壳聚糖微球为载体,采用交联法实现了BgaS的固定化并对交联条件进行优化,确定最适交联条件为:戊二醛26.50 g/L,交联温度35℃,交联时间2.5 h,酶添加量5.94 U/mL,优化后酶活力回收率达55.11%。固定化酶相较游离酶,最适pH与最适温度相同,且在非最适pH条件下,固定化酶的相对酶活力较游离酶普遍提升了18.23%以上,并且固定化酶在95℃条件下孵育90 min仍保有80%以上的相对活性,较游离酶提升了11.31%。并且固定化酶回收利用率高,操作稳定性好,最适条件下处理3 h即可使牛乳中乳糖含量降低至0.5%以下,达到无乳糖水平,为工业化应用提供了技术支撑。

壳聚糖-凹凸棒石复合材料的制备及其对不同污染物的吸附研究进展

作为新型的吸附材料,凹凸棒石有可再生和低能耗的优良特性,被广泛应用于污水处理方面;壳聚糖由于其可生物降解、抗菌、亲水、可再生、生物相容性和环保等优势被广泛应用于重金属离子、含酚类废水、印染废水等废水处理领域中。而将两种材料复合,则对重金属离子以及难降解有机污染物展现出更加优异的吸附能力。通过综述该复合材料的研究进展,了解到该复合材料对重金属离子以及难降解有机废水的吸附性能对比单一材料都有所提升。最后分析了该复合材料目前研究的局限性并对将来的研究方向进行了展望。

壳聚糖固定化石油烃降解菌的降解性能研究

本研究以筛选获得的一株石油烃降解菌HYHG-06为研究对象,选择壳聚糖为固定化载体材料,戊二醛为交联剂,通过交联反应固定化制备壳聚糖固定化石油烃降解菌;通过改变降解环境的温度、初始pH、盐度及石油烃浓度,探究4个因素对石油烃降解菌降解性能的影响。结果表明,固定化菌的降解性能优于游离菌,在温度30℃、初始pH8.0、盐度3.5%、石油烃浓度1.5%的环境条件下,固定化菌的石油烃降解率高达86.62%,可开发高效消油产品,为海上石油污染提供了一种高效可行的生化处理方法。