Polypyrrole–glucose oxidase biosensor. Effect of enzyme encapsulation in multilamellar vesicles on film growth and morphology

We describe the making of a polypyrrole (PPy)/glucose oxidase (GOx) film using onion-type multilamellar vesicles (MLV) to transport and incorporate the enzyme in the polymer film. The morphology of the film is studied as a function of the synthesis charge by fluorescence microscopy and atomic force microscopy (AFM). Electrochemical analysis shows that encapsulating the enzyme removes the negative influence of GOx on the film growth rate. On the contrary, GOx-containing MLV are shown to act as dopant for the PPy synthesis, drastically increasing the film synthesis rate. Another advantage using MLV for GOx insertion into PPy film is to induce reproducible growth kinetics, while unpredictable kinetics are found with free GOx. Such result is explained by different nucleation mechanisms.