DEVELOPMENT OF A DIAMINE BIOSENSOR

An amperometric diamine sensor is developed for clinical applications in diagnosis of bacterial vaginosis (BV). The sensor is based on cross linked putrescine oxidase (PUO) which catalyzes the conversion of diam ines (mainly putrescine and cadaverine) to products including hydrogen peroxide. The hydrogen peroxide is detected anodically at platinum el ectrode polarized at 0.5 V versus Ag/AgCl. Platinum-plated gold electr odes used as a substrate for the sensor construction, are batch-fabric ated on a flexible polyimide foil (Kapton(R), DuPont). A three-electro de cell configuration is used in all amperometric measurements. The se nsor construction is based on three layers: an inner layer to reject t he interference effect of oxidizable molecules, an outer diffusion con trolling layer, and in addition, an enzyme middle layer. The enzyme la yer was immobilized by crosslinking PUO with bovine serum albumin (BSA ) using glutaraldehyde (GA). An optimization study of the enzyme solut ion composition was carried out. With the optimized enzyme layer, the biosensor showed a very high sensitivity and fast response time of ca. 20 s. The sensor has a linear dynamic range from (0.5-300 mu M) for p utrescine that covers the expected biological levels of the analyte. D etails on sensor fabrication and characterization are given in the pre sent work. (C) 1997 Elsevier Science B.V.