Glucose detection at bare and sputtered platinum electrodes coated with polypyrrole and glucose oxidase

Recently, a glucose sensor has been developed, which is easily prepared, has a good stability and high glucose response, and is interference free for ascorbic acid. The sensor was made by galvanostatic polymerization of 0.3 M pyrrole in a HEPES buffer pH 7.0 with 200 U ml−1 glucose oxidase (GOx) using a current of 1 μA. In this study, bare and sputtered platinum electrodes, coated with polypyrrole in the presence of GOx and/or flavine adenine dinucleotide (FAD), are compared. FAD in excess in the polymerization or sample solution did not increase the glucose response. The selectivity with respect to other mono and oligosaccharides was good. The mechanism of electron transfer was studied. From measurements at low potentials and at anaerobic conditions there is a strong indication that the glucose sensor is a combination of indirect and direct electrontransfer (first and third generation, respectively).