Electrochemically initiated co-polymerization of monomers of different oxidation potentials for molecular imprinting of electroactive analyte

Herein, we report an electrochemically initiated co-polymerization of two electroactive monomers of different oxidation potentials. The molar ratio of low oxidation potential monomer in the solution for electro-polymerization was optimized to find condition suitable for co-polymerization of high-oxidation potential monomer effectively at lower oxidation potential. The XPS analysis confirmed successful co-polymerization. This co-polymerization condition was further used in imprinting of melatonin, an electroactive compound. Entrapment of melatonin in the polymer matrix was confirmed by measuring electroactivity of melatonin in the 0.1 M KCl - HCl solution (pH 1.6). This MIP based electrochemical sensor determined melatonin in the linear dynamic concentration range 10-80 mu M. Delectability of proposed chemosensor was 0.14 mu M (S/N = 3). The mean RSD for the concentration range studied was similar to 20%. Selectivity of the chemosensor was satisfactory towards common structural analogues and biomolecules. Furthermore, the chemosensor was successfully used to determine melatonin in real samples. The sensitivity in the presence of matrix components and that for the KCl - HCl solution were quite similar. The results obtained indicate the suitability of the devised chemosensor for practical applications.