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Abstract
Nanostructured tin oxide (ns-SnO2) was synthesized, characterized, and evaluated for chemical sensing. Carbon paste electrode (CPE), modified with ns-SnO2, was investigated for amperometric determination of hydrogen peroxide. With an operating potential of 1.14 V (vs Ag/AgCl), H2O₂ produces catalytic oxidation current, which can be exploited for quantitative determinations. The amperometric signals are linearly proportional to H2O₂ concentration in the range of 0.035 to 0.35 mmol/L. With glucose oxidase (GOx) as an enzyme model, amperometric glucose biosensor is constructed by bulk modification of the carbon paste electrode with GOx as a biocomponent and ns-SnO₂ as a mediator. The biosensor was evaluated as an amperometric glucose detector at phosphate buffer solution with a pH 7.4 at the same operating potential of 1.14V. The biosensor is characterized by a well-reproducible amperometric response, linear signal-to-glucose concentration range up to 22 mmol/L and a detection limit of 2.67 mmol/L. The biosensor based on ns-SnO₂/GOx exhibited considerable good reproducibility and stability.