Molecularly imprinted polypyrrole-based electrochemical melamine sensors

This study describes the development of a molecularly imprinted polymer (MIP) polypyrrole-based (Ppy-based) electrochemical melamine sensor. Two different modifications of polymeric layers in the design of MIP-based melamine sensor systems were assessed. The addition of gold nanoparticles (AuNPs) or gold(I) complexes in the polymerization solution containing pyrrole was studied. The characteristics of all polypyrrole layers were evaluated indirectly using a [Fe(CN)6]3–/[Fe(CN)6]4– as a redox probe by application of differential pulse voltammetry (DPV). The most optimal results were obtained when the MIP polymerization was prepared from a solution containing 50 mM pyrrole, 5 mM melamine, and 0.05 nM 3.5 nm diameter AuNPs. Under these conditions, the observed response of MIP to melamine was 6.61 times greater than that of non-imprinted polymer (NIP). To further characterize the detection of melamine, overoxidized forms of both MIP and NIP were employed. The utilization of MIP resulted in a linear correlation within the concentration range from 50 nM to 5 µM melamine, with an estimated limit of detection (LOD) of 0.83 nM melamine.