Amperometric Biosensor Based on Enzyme Immobilization with Post Process for Medical and Multiple Applications

Abstract

An amperometric biosensor with a laminar structure for various analytes was fabricated and tested. The biosensor was composed of two platinum thin-film electrodes and a hydrophilic polytetrafluoroethylene membrane. This structure has the advantage of enzyme immobilization for varying purposes in a post-process. The biosensor was fabricated using a simplified four-step coating process: polydimethylsiloxane was applied to the hydrophilic polytetrafluoroethylene membrane as an insulation coating, followed by platinum sputtering to form two thin-film electrodes. An adhesive coating was applied to form an inactive platinum surface and an enzyme immobilization region on the sensing region of the biosensor. The platinum electrodes were used for amperometric measurements. They were useful for the determination of 2.00 to 200 µmol/l of NADH with good precision. The applicability of the biosensor for immobilizing each enzyme: aldehyde dehydrogenase, formaldehyde dehydrogenase, and glucose oxidase in post process was investigated. The calibration ranges of the biosensors for acetaldehyde solution, formaldehyde vapor, and glucose solution were 1.00 to 200 µmol/l, 2.0 to 12 ppm, and 0.100 to 10.0 mmol/l, respectively. The results indicate that the structure and fabrication process of the amperometric biosensor is useful for multipurpose applications.