Fe3O4-modified thick film carbon-based amperometric oxidase-biosensor

Abstract

An amperometric biosensor was developed from screen printed carbon electrodes modified with magnetite as the transducer element and Nafion-entrapped glucose-oxidase as the bio-recognition layer, cast by drop-evaporation. In a flowing stream of phosphate buffer (pH 7.5/0.05M), at a working potential of-125mV vs. Ag/AgCl with an, injection volume of 100 ul, the biosensor has linear range of 7-150 mg l-1 glucose, a sensitivity of 3.8 nA mg-1 1 cm2, and a precision of 2% at 10 mg l-1. Uric acid, xanthine and hypoxanthine at 10 and 1000 mg l-1 do not cause significant error relative to 100 mg l-1 glucose. Ascorbic acid at 100 mg l-1 causes 10-14% deviations- Dilute blood samples showed average recovery rate of 95%. Thus this model biosensor is precise, fairly senstitive and accurate.