A Dopamine Electrochemical Sensor Based on Molecularly Imprinted Poly(acrylamidophenylboronic acid) Film

Molecularly imprinted polymeric films were prepared on the surface of a gold electrode by reductive electrochemical co-polymerization of 3-acrylamidophenylboronic acid (AABA), acrylamide (as spacer monomer), and N,N-methylenebisacrylamide (as crosslinker monomer) in the presence of dopamine in water. The analytical determination of dopamine was investigated with this molecularly imprinted poly(AABA) film-modified gold electrode using cyclic voltammetry, electrochemical quartz crystal balance, and differential pulse voltammetry. The covalent nature of dopamine-boronic acid interaction as well as the negative charge on the molecularly imprinted polymeric film at physiological pH allowed excellent selectivity against ascorbic acid and other structurally similar interferents. The sensitivity of molecularly imprinted poly(AABA)-modified electrode was further improved by depositing a thin layer of multiwalled carbon nanotubes on the gold electrode surface prior to electropolymerization. The increased surface area due to the presence of carbon nanotubes improved the dopamine sensor's detection limit to approximate to 20nM as determined by differential pulse voltammetry. A linear dependence of peak current in the differential pulse voltammograms was obtained over the dopamine concentration range from 50nM to 2 mu M.