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

Download

index.pdf

Date

2009

Author

Eker, Zeynep

Metadata

Show full item record

Item Usage Stats

195
views

57
downloads

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.

Subject Keywords

Nanotechnology., Biotechnology.

URI

http://etd.lib.metu.edu.tr/upload/3/12611022/index.pdf
https://hdl.handle.net/11511/19041

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Determination of metabolic bottlenecks using reaction engineering principles in serine alkaline protease production by recombinant bacillus sp. Telli, İlkin Ece; Çalık, Pınar; Department of Chemical Engineering (2004) In this study, firstly, bioprocess characteristics for Serine Alkaline Protease (SAP) production, using recombinant Bacillus subtilis carrying pHV1431::subC, were examined. The cell concentration, substrate concentration, SAP activity and SAP synthesis rate profiles demonstrated that the system reaches to a steady state in terms of cell growth and SAP synthesis between t=15-25 h, therefore, this time interval is appropriate to employ both metabolic flux analysis and metabolic control analysis, which apply s...
Isolation of antimicrobial molecules from agricultural biomass and utilization in xylan-based biodegradable films Çekmez, Umut; Bakır, Ufuk; Department of Biotechnology (2010) Cotton stalk lignin extractions were performed via alkaline methods at different conditions. Crude and post treated cotton stalk lignins, olive mill wastewater and garlic stalk juice were examined in terms of antimicrobial activity. Antimicrobial lignin was isolated depending on alkaline extraction conditions. Lignin extracted at 60°C exhibited significant antimicrobial effect towards both Escherichia coli and Bacillus pumilus. However different post treatments such as ultrasonication and TiO2-assisted phot...
MODEL FOR TRANSIENT MOISTURE PROFILES OF A DRYING APPLE SLAB USING THE DATA OBTAINED WITH MAGNETIC-RESONANCE-IMAGING MCCARTHY, MJ; PEREZ, E; OZILGEN, M (Wiley, 1991-11-01) The use of magnetic resonance imaging (MRI) spectroscopy as a real time probe to noninvasively obtain transient moisture profiles during food dehydration is demonstrated. A laboratory-scale wind tunnel drier was constructed. A 2 x 5 x 5 cm3 apple slab was inserted in the probative zone and one-dimensional drying was effected at quasiisothermal conditions. Spatial resolution of 0.60 mm was obtained. The transient moisture profiles were simulated with a simple mass transfer model. Effective diffusivity of wat...
Determination and metabolic engineering of rate limiting reactions in aromatic amino acid pathway in Bacillus subtilis for L-phenylaianine production Guzide, Calik; Yasemin, Demirci; Pinar, Calik; Ozdamar, Tuncer H. (2007-09-01) Rate limiting reactions in the aromatic-group amino acid pathway (AAAP) in Bacillus subtilis for l-phenylalanine (Phe) production were determined as reported elsewhere (Özçelik-Şenver et al., 2004). The biochemical reactions in the AAAP start with the reaction using phosphoenolpyruvate (PEP) and erythrose 4-phosphate (E4P) synthesised in the glycolysis pathway and the PPP, respectively, leading to the formation of Phe via chorismate by branching at prephenate. The branch-point metabolites E4P supplied in vi...
Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus Sevinç, Pelin; Gündüz, Ufuk; Department of Biotechnology (2010) Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 – 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth...

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.