Immobilization of Alcohol Dehydrogenase on Films Prepared by the Electrochemical Copolymerization of Pyrrole and 1-(2-Carboxyethyl)pyrrole for Ethanol Sensing

摘要

The electrochemical copolymerization of pyrrole and 1-(2-carboxyethyl)pyrrole (Py-COOH) was carried out, and a conducting polymer film with a Py-COOH content of 5% and a conductivity of 6.6 x 10(-4) S/cm was obtained. Alcohol dehydrogenase (ADH) was attached through amide linkage onto the surface of the conducting polymer film for the purpose of fabricating an ADH-immobilized electrode applicable to the amperometric sensing of ethanol. The quantity and activity of the immobilized ADH were determined to be 400 mu g/cm(2) and 0.6 U/mg, respectively. With the ADH-immobilized electrode, amperometric ethanol sensing was attempted in the presence of nicotinamide adenine dinucleotide (a cofactor of ADH) and Meldola's blue (an electron-transferring mediator). The ADH-immobilized electrode made the current response correspond to ethanol concentration, which reached 10 mu A/cm(2) at a concentration of 14 mM. The selectivity of the sensing was examined with alcohols other than ethanol. It was found that the ADH/copolymer electrode had a considerably larger current response to allyl alcohol. The selectivity was attributed to the specificity of native ADH with respect to the oxidation of alcohols.