Preparation and characterization of titania-silica-gold thin films over ito substrates for laccase immobilization

Eker, Zeynep
The aim of this study was to immobilize the redox enzyme laccase over TiO2-SiO2-Au thin film coated ITO glass substrates in order to prepare electrochemically active surfaces for biosensor applications. Colloidal TiO2-SiO2-Au solution was synthesized by sol-gel route and thin film was deposited onto the substrates by dipcoating method. The cysteamine was utilized as a linker for immobilization of enzyme covalently through gold active sites. Preliminary studies were conducted by using invertase as model enzyme and Pyrex glasses as substrates. The effect of immobilization parameters such as immobilization temperature, concentration of enzyme deposition solution, immobilization time for laccase were examined. Leakage studies were conducted and storage stability of immobilized laccase was determined. Highest laccase activity was achieved when immobilization was performed with 50 µg/ml solution at 4°C for 2 hours. Laccase activity decreased after 4 hours of impregnation in enzyme solution. Laccase leakage was observed in the first usage of substrates and 55% activity decrease was determined in the subsequent use which might be attributed to the presence of uncovalently adsorbed enzyme on the fresh samples. In air and in buffer storage stabilities were also tested. It was found that the activity of samples almost vanished after 6 days regardless of storage conditions. Both enzymes had more activity on ITO substrate.


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Çınar, Merve; Bakır, Ufuk; Department of Chemical Engineering (2009)
The aim of this study was to investigate the viability of patterning by immobilization, photocatalytic removal, and re-immobilization steps of the enzyme on photocatalytically active thin films for biosensor fabrication purposes. For this aim, TiO2-SiO2-Au sol-gel colloids were synthesized and deposited on glass substrates as thin films by dip coating. Cysteamine linker was assembled on gold nanoparticles to functionalize thin films with amine groups for immobilization of model enzyme invertase. Effect of i...
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Preparation of Chitosan-Coated Magnetite Nanoparticles and Application for Immobilization of Laccase
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In this study, immobilization of laccase (L) enzyme on magnetite (Fe(3)O(4)) nanoparticles was achieved, so that the immobilized enzyme could be used repeatedly. For this purpose, Fe(3)O(4) nanoparticles were coated and functionalized with chitosan (CS) and laccase from Trametes versicolor was immobilized onto chitosan-coated magnetic nanoparticles (Fe(3)O(4)-CS) by adsorption or covalent binding after activating the hydroxyl groups of chitosan with carbodiimide (EDAC) or cyanuric chloride (CC). For chitosa...
Citation Formats
Z. Eker, “Preparation and characterization of titania-silica-gold thin films over ito substrates for laccase immobilization,” M.S. - Master of Science, Middle East Technical University, 2009.