Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 The effect of Cu/Fe substitution on the crys tallization behav ior and mag netic properties of ferrimagnetic glass ceramic rich with magnetite S. A. M. Abdel-Hamed0T 1 and M. A. Marzouk 1 * 1 Glass Research Department, National Research Center, Dokki, Cairo, Egypt Abstract-Ferrimagnetic glass-ceramic with high quantity of magnetite (~60%) were synthesized from the system Fe 2 O 3 .CaO.ZnO.SiO 2 . The influences of adding different amount of CuO and melting temperature on the crystallization of magnetite were studied. The X-ray diffraction patterns show the presence of nanometric magnetite crystals in a glassy matrix after cooling from melting temperature. The crystallization of magnetite was increased by increasing amounts of CuO added and melting temperatures. TEM were used t o study the microstructure. Magnetic hysteresis cycles were analyzed using a vibrating sample magnetometer with a maximum applied field of 10 kOe, at room temperature, in quasi-static conditions. From the obtained hysteresis loops, the saturation magnetization (Ms), remanance magnetization (Mr) and coercivity (Hc) where determined. 6th Nanoscience and Nanotechnology Conference, zmir, 2010 292
Poster Session, Tuesday, June 15 Theme A1 - B702 Immobilization and Characterization of Thermophilic Recombinant Esterase on Chitosan Nanoparticles 1 ,Taylan Turan 1 and 1 * zmir Institute of Technology, Faculty of Science, Department of Chemistry, Gülbahce Köyü Kampüsü, Urla, Izmir, 35430, Turkey 1 Abstract— Immobilization of biologically important molecules on myriad nano-sized materials has attracted great attention. Through this study, homemade esterase enzyme was obtained using recombinant DNA technology. Enzyme over expression in Escherichia coli and purification were carried out successfully. At the next step, chitosan was synthesized from chitin by deacetylation process and degree of deacetylation was calculated as 89% by elemental analysis. Characterization of chitosan was studied by applying FT-IR (Fourier Transform Infrared Spectroscopy). After preparation of chitosan and chitosan/esterase enzyme nano-particles, their surface morphologies and structures were examined by AFM (Atomic Force Microscopy) and SEM (Scanning Electron Microscopy). In order to investigate the characterization of esterase enzyme immobilized on chitosan nano-particles, the experimental studies in terms of activity, substrate specificity, the effect of temperature and pH on the activity, optimum temperature and pH values, the effect of variety of metals, inhibitors and detergents on activity and thermal stability are being under examination. The characterization data of enzyme immobilized chitosan nano-particles will be compared with free enzyme for their potential uses as biocatalysts in variety of biotechnological applications. Recently the majority of industrial enzymes produced by micro-organisms are being utilized widely and their utilization on very diverse area of industry is increasing rapidly in the world day by day. Especially, enzymes from thermophiles have many advantages for industrial applications because they are very thermo stabile and thermo active under high temperatures. In that study, we have used recombinant thermophilic esterase enzyme from Balçova Geothermal region [1]. Esterase enzymes are special interest in a variety of biotechnological applications because of their many useful properties. Immobilization of enzymes is very important not only for reuse of them but also for use them more efficient. As compared to free enzymes in solution immobilized enzymes are more robust and more resistant to environmental changes. Therefore, many kinds of immobilization techniques have been improved for many years on various supports and by different methods. One of the most used biopolymer as immobilization carriers, chitosan offer a unique set of characteristics: biocompatibility, biodegradability to harmless products, nontoxicity, physiological inertness, antibacterial properties, heavy metal ions chelation, gel forming properties and hydrophilicity, and remarkab le affin ity to proteins [2]. Recently, researchers have indicated that nano-sized materials can be used for immobilization of enzymes. To the best of our knowledge, studies of enzyme immobilization on Chitosan nano-particles have been rarely reported. In this study, chitosan nano-particles were prepared by ionic gelation methodology. Thermophilic recombinant esterase was initially over-expressed in E.coli and then purified by one-step affinity chromatography with high yield and good purity. Thermophilic recombinant esterase was immobilized on chitosan nano-particles and conditions for the immobilization and characterization of the immobilized enzyme were studied systematically. Figure 1 shows AFM images of Chitosan/Recombinant-Esterase Nano-particles. Figure 2 shows SEM images of chitosan nano-particles and chitosan/Recombinant-Esterase nano-particles. a) b) Figure 2. SEM images of a) Chitosan nano-particles, b) Chiosan/Esterase nano-particles. As a result of our studies, it is expected that the immobilized enzy me will exh ibit remarkab ly improved stability properties to various parameters, such as temperature, reuse and storage time. Thus nano-particles will be suitable for an immobilized enzyme carrier. *Corresponding author: gulsahsanli@iyte.edu.tr [1] Tekedar, H., 2009. Molecular Cloning, Overexpression and Characterization of Thermostable Esterase and Lipase from Thermophilic Bacillus sp., Master’s Thesis, IYTE. [2] Krajewska, B., 2004. Application of chitin- and chitosan-based materials for enzyme immobilizations: a review, Enzyme and Microbial Technology, 35: 126-139. [3] Tang, Z. X., Qian, J. Q., Shi, L. E., 2007. Preparation of Chitosan Nanop articles as carrier for immobilzed enzyme, Appl. Biochem. and Biotech., 136: 77-96. Figure 1. AFM images of Chitosan /Recombinant-Esterase Nanoparticles 6th Nanoscience and Nanotechnology Conference, zmir, 2010 293
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