The fabrication of structurally multiordered polyaniline films and their application in electrochemical sensing and biosensing

Structurally multiordered thin films composed of conducting polymer polyaniline (PANI) were fabricated on homemade screen-printed carbon electrodes (SPEs). Formation of monolayered sulfate- or amine-modified PS templates on bulk polyaniline was assisted by various polyelectrolytes - negatively charged poly(sodium 4-styrenesulfonate) (PSS) and positively charged poly(diallyldimethylammonium chloride) (PDDA). Additional layers of PANI with controlled thickness were electrodeposited on the templated PANI-SPEs. Different morphologies of the outermost PANI films were obtained including PS-PANI core-shell and PS-PANI composites. It is shown that the surface charge of PS templates determines different mechanisms of polymer growth, which results in the above structures. The fact that nanostructured PANI films are grown on bulk PANI significantly increases the surface area and enhances the catalytic properties of such films. Removal of template particles by dissolving in toluene resulted in PANI hollow spheres and dimpled, semi-porous PANI films, respectively. As-prepared electrodes were used for the electrocatalytic reduction of nitrite. Upon further modifications with horseradish peroxidase, a biosensor was developed which could be used for the amperometric determination of H2O2. In the case of both analytes, catalytic responses were obtained only on multiordered PANI films. Difference in responses have been explained in terms of different morphologies and the different thickness of the outermost layers of PANI. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.