Oxygen-independent poly(dimethylsiloxane)-based carbon-paste glucose biosensors

Several silicone oils have been assessed and compared as an internal source of oxygen in connection to their use as binders for carbon-paste glucose biosensors. All four poly(dimethylsiloxane) (PDMS) oils tested a dramatic increase in the oxygen capacity of carbon-paste enzyme electrodes to allow convenient biosensing under severe oxygen-deficit conditions. The resulting oxygen independence is better than that exerted by perfluorocarbon binders or that displayed by mediator-based bioelectrodes. The resistance to oxygen effects is indicated from the identical response (observed in the presence and absence of oxygen) up to 2 x 10(-2) M glucose and the slight (12%) sensitivity loss at 4 x 10(-2) M. The influence of the viscosity of the PDMS binder upon the internal oxygen supply is examined. The PDMS carbon-paste enzyme electrode displays a stable glucose response over prolonged (15 h) operation in an oxygen-free solution. On-line continuous testing indicates favorable dynamic properties with no carry-over effects over the physiological and pathophysiological range (3-12 mM glucose).