Boronate affinity-based molecularly imprinted organic electrochemical transistor sensor for the selective detection of dopamine

Organic electrochemical transistors (OECTs) have gained wide application in the detection of small redox-active molecules like dopamine (DA) due to their low operating voltage, high transconductance, and excellent compatibility in aqueous environments. However, achieving selective detection of DA remains challenging, as the sensing mechanism is dependent on the gate voltage shift, which is influenced by redox reactions at the gate electrode. To enhance selectivity in DA detection, a molecularly imprinted polymer (MIP) made of polyaniline-phenyl boronic acid (PANI-PBAc) and reduced graphene oxide (rGO) was used as the gate electrode. MIP@PANI-PBAc/rGO composite allows for selective recognition of DA molecules, generating a sensing signal through the voltage drop caused by DA redox reactions. The sensor benefits from the boronate affinity binding in the MIP and oxidation processes at the electrode, ensuring high recyclability. The OECT sensor with a MIP@PANI-PBAc/rGO gate demonstrated a low detection limit (1 nM) and good linearity (up to 353 μM), making it suitable for detecting DA in biological fluids. Furthermore, the sensor's response to potential interferents like ascorbic acid and uric acid was significantly lower compared to DA, highlighting its selectivity. This sensor was also tested on real samples and delivered satisfactory results for DA detection.