Using multilamellar vesicles to incorporate glucose oxidase into a polypyrrole film

We report the immobilization of glucose oxidase into a polypyrrole layer owing to multilamellar vesicles. Multilamellar vesicles consist of a mixture of lipids and surfactants and are used to encapsulate glucose oxidase and vectorize it towards an electrode where polypyrrole is electrosynthesized. We show by cyclic voltammetry experiments performed on vesicles free of glucose oxidase that they are likely to interact with pyrrole oligomers during synthesis, leading to their incorporation into the film. Their engulfment into the film is evidenced by scanning electron microscopy and Auger analysis. Vesicles in which glucose oxidase is encapsulated do not seem to be destroyed during film synthesis since the enzymatic activity of the mixed film can be triggered by adding a surfactant able to dissolve the vesicles. The advantage of using vesicles for inserting an enzyme into a polymer film is demonstrated in the special case where a pulsed field is applied for film synthesis. We indeed measure a higher enzymatic activity when glucose oxidase is incorporated in the polypyrrole film using multilamellar vesicles.