Date of Award
Master of Science
Ti/TiO2 based electrochemical impedance spectroscopy (EIS) biosensor can detect the peanut protein Ara h1, an allergenic food protein using a mouse monoclonal IgG1 antibody immobilized onto the electrode surface. Because of the biocompatibility of Ti, and the self-limiting thickness of TiO2, Ti/TiO2 is an attractive alternative electrode material for impedance biosensors to improve the stability and reproducibility of protein immobilization. Three different pretreatment methods for optimizing Ti/TiO2 substrate properties were studied. The best electrode preparation is first to apply a cathodic potential to remove the Ti native oxide from the sputtered Ti films, and then galvanostatically anodize Ti to grow ~10 nm oxide layer in 1.0 M H2SO4. Nitrogen doping is accomplished by annealing for one hour at 600°C in NH3/N2 in a tube furnace after anodization. The carboxylate functional reagent was attached on the surface through a phosphonate group. This reagent is used to attach mouse monoclonal antibodies to the TiO2 electrode through amide bond formation using EDC/NHSS. Peanut protein Ara h1 can then be detected at the Ti/TiO2 sensor electrodes. The charge-transfer resistance (Rct) as a function of Ara h1 concentration follows the Langmuir adsorption isotherm. Cathodic DC potential applied during EIS measurement and plasma nitriding to further improve TiO2 electrocatalytic activity were studied.
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