Direct glucose determination in blood using a reagentless optical biosensor

This paper demonstrates that glucose determination in blood can be done directly (without sample pretreatment) using a reagentless reversible biosensor based on the intrinsic spectroscopic properties of peroxidase (HRP). The biosensor, prepared by HRP and glucose oxidase entrapment in a polyacrylamide gel matrix, works in continuous mode, presents a linear response range from 1.5 × 10−6 up to 5.5 × 10−5 M and can be used for at least 750 measurements; in the best conditions (0.1 M pH 6 phosphate buffer, HRP and GOx amounts in the polymersation mixture for the sensor film preparation 0.0165 and 0.0010 g, respectively) the minimum samples rate is 30 h−1. For glucose determination, blood is simply diluted in water (until haemolysis is completed) and fed into the sensor without a cleaning step between samples; the blood absorption is corrected in a simple way by working at a proper reference wavelength. The biosensor signals have been mathematically modeled in order to facilitate the design of sensors based on the same idea for other biochemical compounds.