Conducting polymers in modelling transient potential of biological membranes

The possibility of using conducting polymer (CP) films doped with biological ligands as artificial biological membranes to study potential formation mechanisms is presented. Calcium and magnesium ion-binding anionic sites--asparagine, glutamine, adenosinotriphosphate and heparin are incorporated into the poly(pyrrole) film during electrochemical polymerization. This approach allows the competitive calcium-magnesium ion-exchange to be inspected by open circuit measurements. After a close-to-Nernstian sensitivity of the CP membranes was induced by soaking in alkaline solutions of calcium or magnesium, dynamic experiments were performed by a change in the bulk concentration of magnesium or calcium ions. A characteristic transitory potential response, though distinctively different for the calcium and magnesium ions, was observed and explained using the diffusion layer model (DML).