Ti-Based Solid-State Imprinted-Cu2O/CuInSe2 Heterojunction Photoelectrochemical platform for Highly Selective Dopamine Monitoring

An innovative method is developed based on a surface functional photoactive monomer-directing assay for the design of an ultrasensitive and selective molecularly imprinted polymer (MIP) grown on a semiconductor heterojunction for photoelectrochemical dopamine recognition. A dopamine-imprinted poly-orto-phenylenediamine (P-o-PDA) coated on Ti foil electrode is modified with a new double photosystem type II heterojunction formed by coupling dendrite-like CuInSe2(CIS) with Cu2O nanoparticles. It was prepared by electropolymerization, which provided high capacity and fast kinetics to monitor dopamine as biomarker. o-PDA acts as a signal indicator and a functional monomer for MIP. In addition, Cu2O/CIS acts as photoelectric convertor and amplifier layer for PEC-sensing. Under visible light irradiation, the MIP-CIS/Cu2O-coated Ti foil exhibited admirable cathodic photocurrent response, owing to the p-type properties of CIS/Cu2O heterojunction, where signal quenching was obtained in the presence of dopamine due to hindrance effect. Influence of factors including pH, light wavelength and applied bias potential on the PEC response toward dopamine was optimized and the MIP-CIS/Cu2O-based PEC sensing system exhibited satisfying responses toward target dopamine within two working range from 0.1-5.5 μM and 5.5-150 μM at a low detection limit of 2.1 nM. The PEC sensor designed with high photo-electron conversion efficiency showed good stability, high reproducibility, repeatability and selectivity. Its feasibility for potential applications was also illustrated in the analysis of real samples, providing a novel way for the logical design of organic-inorganic heterojunction-based PEC sensors to detect biomarkers.