Biosensors based on light-addressable potentiometric sensors for urea, penicillin and glucose

Abstract

Novel potentiometric biosensors based on light-addressable potentiometric sensors for detection of glucose, penicillin and urea as model compounds are described. n-type silicon substrates covered with SiO 2 and/or Al 2O 3 were applied as a pH sensor. The Al 2O 3 and SiO 2 films were pH-sensitive in the range pH 3–11. The pH-sensitive electrode was applied to produce biosensors for glucose, penicillin and urea by immobilizing glucose oxidase, penicillinase and urease, respectively, on the insulating films. For the glucose and urea sensors, a linear relationships between glucose and urea concentration and bias potential was obtained below 4 mM and 15 mM, respectively. The sensitivity of the glucose sensor was improved by the presence of hexacyanoferrate(III) as an alternative to O 2, which reacts with the coenzyme of glucose oxidase and produces two protons. Penicillin was measured in the range 5–25 mM.