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

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 SiO2 and/or Al2O3 were applied as a pH sensor. The Al2O3 and SiO2 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 O2, which reacts with the coenzyme of glucose oxidase and produces two protons. Penicillin was measured in the range 5–25 mM.