Green in situ reduction synthesis of Cu3(HHTP)2/APBA-rGO: a synergistic platform for dopamine electrochemical sensing.

Dopamine (DA) is a key neurotransmitter, and its abnormal levels are closely associated with several neurological disorders. Herein, an environmentally friendly in situ reduction strategy is proposed to fabricate a Cu3(HHTP)2/APBA-rGO composite for DA sensing with remarkable sensitivity and selectivity. In this strategy, Cu+ ions simultaneously reduce graphene oxide (GO) to reduced graphene oxide (rGO) without any external reductant and are oxidized to Cu2+, which then coordinates with 2,3,6,7,10,11-triphenylenehexol (HHTP) to form Cu3(HHTP)2 directly on the rGO surface. 3-Aminophenylboronic acid (APBA) is pre-grafted onto GO to achieve specific recognition of DA and to improve the dispersion of the composite. The resulting composite synergistically combines the high conductivity of rGO, the electrocatalytic capacity of Cu3(HHTP)2, and the specific DA recognition of APBA. The successful formation of the composite was confirmed by SEM, EDS, XRD, FTIR spectroscopy and Raman spectroscopy. Electrochemical measurements revealed that the Cu3(HHTP)2/APBA-rGO-modified electrode exhibited a broad linear range from 0.25 to 616.25 μM, a low limit of detection of 0.05 μM (S/N = 3), and an outstanding sensitivity reaching 627.57 μA·mM-1·cm-2. Moreover, the sensor exhibited satisfactory reproducibility, prominent interference resistance, and favorable storage stability. The present study provides an environmentally friendly and facile approach to construct MOF-based nanocomposites for reliable detection of DA.