Development of an amperometric biosensor based on a redox-mediator-doped polypyrrole film

Abstract

An amperometric biosensor was developed for the quantitative estimation of phenolic compounds in aqueous media. The enzyme tyrosinase [poly(phenol oxidase) (PPO)] was adsorbed onto a hexacyanoferrate(II)-iondoped conducting poiypyrrole (PPY) film deposited on an indium tin oxide (ITO) coated glass-plate support. The PPO activity in the PPO/Fe2--PPY/ITO film was assayed as a function of the concentration of phenolic compounds. Cyclic voltammetric studies were carried out on this enzyme electrode, and the surface morphology of the enzyme-immobilized polymer film was studied with scanning electron mi-croscopy. The results of the amperometric response of the PPO/Fe2+-PPY/ITO film showed sensitivities of 0.14, 0.21, and 0,36 A M-1cm-2 and linear response ranges of 9.9-84.7, 6.7-72.6, and 3.9-48.8 μM for phenol, catechol, and p-chlorophenol, respectively. The PPO/Fe2+-PPY/ITO electrode exhibited a response time of about 50 s and was stable for about 12 weeks at 4°C. © 2004 Wiley Periodicals, Inc.