Development of electroanalytical sensors based on electropolymeric films and molecular imprinting technology

Molecular imprinted polymers can be obtained by different methodologies, electropolymerization may be an efficient one due to its simple and fast synthesis and easy coupling with electrochemical techniques. Figure 1 shows the cyclic voltammograms (CVs) corresponding to the synthesis of molecular imprinted polymer (MIP) based on o-phenylenediamine (10.0 mmol/L) and pyrrole (5.0 mmol/L) monomers and ascorbic acid (10.0 mmol/L) as model template molecule in acetate buffer solution, pH 5. Non-imprinted polymer (NIP) was obtained in the same way, however, the template was not used. For both cases, the high oxidation currents suggest the formation of the polymeric film on the Glass Carbon (GC) electrode. Figure 2 shows the CVs corresponding to the electrochemical response of GC, GC-NIP and GC-MIP electrodes before and after extraction of the template, and after incubation in a template solution, using K3[Fe(CN)6] as electrochemical probe. Template extraction is performed by CV in NaOH 0.1 mol/L. Small currents are observed for GC-NIP and GC-MIP before template extraction because the film hinders the diffusion of the probe from solution to the electroactive surface of the electrode. For GC-MIP after template extraction, the current increases remarkably due to the channels left in polymeric matrix by template molecules. After incubation in a solution containing ascorbic acid (5 mmol/L and 10 mmol/L), the template molecule rebinds to the polymer, which is evidenced by the decreasing currents.