Surface imprinted conducting polymer patterns electrochemically grown from gold pinhole arrays on 2D inverse silica opals and their effective use in aspartame detection

This paper introduces a novel method to electrochemically grow surface imprinted poly(3-TAA-co-EDOT) patterns from a gold pinhole array inside an inverse silica opal monolayer for the detection of aspartame. Using colloidal lithography, the designed 2D silica opal photonic crystal acts as an insulating porous mask with exposed gold pinhole arrays to form molecularly imprinted conducting polymers (MICPs). As the number of cyclic voltammetry (CV) cycles is increased, the MICPs grew toward the silica inner wall retaining the imprinted pillar array formed on the gold pinholes. For all three types of MICP films investigated (i.e., CV1, CV3, and CV5), artificial recognition sites were successfully generated after aspartame extraction; aspartame adsorption was then investigated using quartz crystal microbalance measurements. In the case of MICP-CV5, all of its sensing properties such as sensing response (Δf), imprinting effect (If), and selectivity were found to be superior to those measured for the other polymers (i.e., MICP-CV1 and −CV3). Furthermore, the MICP-CV5 film demonstrated significantly enhanced sensing behavior relative to 2D inverse porous MICP (p-MICP) films with similar surface morphologies, which were grown electrochemically by conventional polystyrene colloidal lithography. Overall, the results presented herein clearly demonstrate that this novel lithographical method leads to an increased number of imprinting sites in MICP structures, which impart the resultant polymers with enhanced sensing properties.