Papers by Keyword: Immobilisation

Abstract: Candida rugosa Lipase was immobilized on the activated nylon-6 membrane using 0.5% glutaraldehyde as cross-linking agent. The immobilized lipase had an improved temperature and pH stability and exhibited good reusability. The adsorption process followed pseudo-second order rate equation and the biosorption isotherms correlated well with the Langmuir isotherm model. Negative ΔG indicated the adsorption process was spontaneous and the positive of ΔH indicated that the adsorption was endothermic.

Abstract: Utilize of property evaluation method for an immobilizing procedure is very important. In this paper, an immobilizing procedure was used to stabilize heavy metals in tested soils. Tessier sequence extract procedure (SEP), toxicity leaching procedure (TCLP) and simple bioaccessibility extraction test (SBET) were used to evaluate the efficiency of the stabilization procedure. The leachability, bioaccessibility and speciation of As, Cu and Pb in the tested soils were analyzed using Tessier SEP, TCLP and SBET method separately. The results indicated that the most active part of the heavy metals could be extracted out by TCLP method and it could be used to evaluate the risk of the tested soils. Tessier method divided heavy metals in soils to different fractions. Monitoring the changes of different fractions during the immobilizing procedure could help fully understand the mechanism of stabilization. The SBET method simulated the human digest system and evaluated the risk changes to human during the immobilizing procedure. And it helped to reveal the potential risk of chemical stability. In our project, these three evaluation method should be utilized properly to help accessing the risk, electing suitable immobilizing method and evaluating the efficiency of stabilization.

Abstract: Variations of heavy metals in sludge during microwave pyrolysis and muffle pyrolysis were analyzed by means of scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectrometer (ICP-AES). Increased basicity of residues from the sludge is found. Leaching percentages of heavy metals ranging from 0.031% to 5.364% after microwave treatment are lower. Releases of cadmium, lead, zinc and copper from the residues obtained in microwave pyrolysis reduce by 92.68% compared with muffle pyrolysis. Alkaline intermediates formed in the pyrolysis residues bring about improved immobilization of heavy metals. Transformation in morphology of heavy metals and strong alkaline of the residues, lead to the immobilization of heavy metals during microwave pyrolysis.

Abstract: Coordinated chitosan-Cu²⁺ as a carrier, the laccase was immobilized on it by polymeric coordination method. In this study, the optimal conditions for immobilization and properties of laccase were investigated. The optimal conditions for immobilization were: CuSO₄ (0.05 mol/L), complex time (7 h), laccase concentration (250 U/mL), immobilization time (8 h). Under this condition, the activity of immobilized laccase can reach 820 U/g. In comparison with the free laccase, the optimum pH and temperature of immobilized laccase have a little change, while the heat resistance and pH stability were improved. After the immobilized laccase was stored in the refrigerator at 4 °C for 25 days, the activity of it remained 69.5 % of the original, it illustrates the immobilized laccase has a good storage stability. The laccase immobilized with chitosan-Cu²⁺ has high activity and has potential to use in industry as a biocatalyst.

Abstract: A method for preparing a high-density His-tagged protein array was developed. The method is based on specific binding between His-tags and Ni ions chelated with the carboxyl groups of L-cysteine applied to the substrate surface by electrodeposition. About 13 ng/mm² of His-tagged green fluorescent protein (His-GFP) could be immobilized on the substrate. The immobilized His-GFP could be subsequently released by washing with imidazole, suggesting that immobilization involves specific binding between the His-tag and the Ni ion complex.

Abstract: The present study aimed to characterize the agricultural residues of sugarcane bagasse {SB} and pineapple core {PC} for the use in immobilization of Lactobacillus rhamnosus NRRL 442. Using Standard Official Methods, SB and PC were found to contain approximately equal amount of nutrition content. The nutrition contents found include: 2.7-2.8 % of protein, 9.8-10 % of crude fiber, and 0.3-0.5 % of fat. On the other hand, SB demonstrated relatively higher solution holding capacity of 9.42 ± 2.3 g/g dry size sample than that of 6.04 ± 2.1 g/g dry size sample in PC. Under screening electron microscope, the fiber of SB has a flat and even surface; in contrast, the fiber of PC has a rough and overlapping surface which may promote the attachment or cell holding capacity during the immobilization process. However, the viability tests after cells immobilization have shown that SB provided higher cell survivability of 93.6 % than that of 64.1% in PC. These result highlighted the greater role of solution holding capacity of cellulose in ensuring a better cell survivability after immobilization process. As conclusion, this study showed the near future potentiality of SB and PC as immobilization carriers for Lactobacillus rhamnosus NRRL 442. It may substitutes proportionally of raw materials and be functional feed for ruminant.

Abstract: The bioleaching of sulfide minerals by iron oxidizing bacteria are implemented by direct and indirect mechanisms. The direct dissolution of minerals is caused by the attack of sulfide ions by enzymatic system of bacteria. In the indirect mechanism the ferric ion from oxidation of ferrous iron serves as a leaching agent that reacts chemically with the minerals. The increase of ferrous ion oxidation contributes to the intensification of bioleaching process. On this purpose the immobilization of iron oxidizing bacteria on different organic and inorganic carriers (calcium alginate, carragiran, ceramic support, activated carbon, porous glass, etc.) has been implemented which allows to increase cell concentration. In the present work for the first time the native shungit, zeolit and their chemically modified forms have been used for immobilization of new isolated iron oxidizing bacteria of the genera Leptospirillum and Sulfobacillus. Efficient physico-chemical conditions for immobilization on the mentioned carriers have been developed. The ferrous ion oxidation by immobilized cells has been studied both in shake-flasks experiments and in the glass column using air-lift process. It has been shown that in both cases the rate of iron oxidation considerably enhances in comparison with free cells.

Abstract: Electrically conducting polymers (ECPs) are finding applications in various fields of science owing to their fascinating characteristic properties such as binding molecules, tuning their properties, direct communication to produce a range of analytical signals and new analytical applications. Polyaniline (PANI) is one such ECP that has been extensively used and investigated over the last decade for direct electron transfer leading towards fabrication of mediator-less biosensors. In this review article, significant attention has been paid to the various polymerization techniques of polyaniline as a transducer material, and their use in enzymes/biomolecules immobilization methods to study their bio-catalytic properties as a biosensor for potential biomedical applications.

Abstract: In this paper,tannase was immobilized by the method of the pre cross-linking,embedding and re cross-linking.The orthogonal design is carried out on the basis of single factor,by which the optimum conditions of the immobilized tannase was selected out ,the optimum pre cross-linking and re cross-linking concentration of glutaraldehyde is 0.3%(v/v )and 0.4%(v/v),respectively,the pre cross-linking temperature is 30°C and the re cross-linking time is 1.0h.in addition,the optimum catalytic temperature is 50°C and the optimum catalytic pH is 5.0,and compered with the free tannase ,the temperature and the pH stability of immobilized tannase improved markedly.

Abstract: Bisphenol A based epoxy acrylate (BABEA), a commercial ultraviolet (UV)-curiable material, was introduced as a new manufacturing material for facile fabrication of epoxy-functionalized films through UV-initiated copolymerization using glycidyl methacrylate (GMA) as the functional monomer. X-ray photoelectron spectroscope (XPS) results indicated the existence of epoxy groups on the surface of the poly (BABEA-co-GMA), which allowed for binding protein through an epoxy-amino group reaction. The contact angel results indicated the poly (BABEA-co-MMA) is hydrophilic, which avoided nonspecific adsorption of biological species. Bovine serum albumin (BSA) was successfully immobilized on the poly (BABEA-co-GMA) films by using the introduced epoxy groups effectively. This makes it possible to extend the application of such films in the fields of bio-separations and bio-recognitions.