Molecularly imprinted polypyrrole films: Some key parameters for electrochemical picomolar detection of dopamine

Dopamine-imprinted polypyrrole films were electrochemically prepared on glassy carbon electrodes in aqueous solutions of pyrrole, dopamine (DA) and LiClO4 as supporting electrolyte. Cyclic voltammetry and chronoamperometry were compared as electropolymerization methods. The dopamine template molecule was successfully trapped in the polypyrrole (PPy) film where it created artificial recognition sites. After extraction of the template, the PPy film acted as a molecularly imprinted polymer (MIP) for the specific and selective recognition of dopamine whereas the non imprinted polymer (NIP) film did not exhibit any oxidation peak which demonstrates that the imprinted PPy fims are specific towards dopamine. The performance of the MIP films was optimized by selecting chronoamperometry rather than cyclic voltammetry as a method of MIP preparation, however for a short electropolymerization time of 15 s. The optimal thickness for the detection of dopamine was 100 nm. The dopamine-imprinted PPy films were found to selectively detect dopamine against the interferents ascorbic acid (AA), 2-phenyl ethylamine (PEA) and noradrenaline (NAD). The limit of detection (LOD), achieved via square wave voltammetry was as low as 5.7 pmol L−1. This work highlights the possibility to design, via a simple and rapid electrochemical fabrication procedure, molecularly imprinted polymer films for specific, selective and ultrasensitive electroanalysis of molecules.