QCM sensing of melphalan via electropolymerized molecularly imprinted polythiophene films

A sensor for the determination of melphalan (mel) using 3-thiophene acetic acid (3-TAA) as functional monomer was fabricated by electropolymerization on gold surface. The polymeric film was formed on the surface of gold electrode as well as on gold-coated electrochemical quartz crystal microbalance (EQCM) electrode by electropolymerization of 3-TAA in presence of mel template by cyclic voltammetry (CV). Various parameters were optimized for controlling the performance of molecularly imprinted polymer (MIP) modified sensor such as ratio of monomer and template ratio, number of electropolymerization cycles, mass deposited in each cycle, pH, etc. The prepared MIP sensor was highly specific towards mel and the recognition was analyzed by both differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) to verify the changes in currents. In the optimal condition, response of MIP sensor to mel was linearly proportional to its concentration with limit of detection (LOD) as 5.40 ng mL−1. Hence, a highly sensitive and selective piezoelectric sensor for mel has been reported here via imprinting approach for the first time.