DBD plasma-activated 2D hollowed leaf-structured ZIF-PDA-Fe for enhanced performance in dopamine electrochemical sensing

Given that dopamine (DA) is an essential neurotransmitter for regulating physiological functions, the accurate detection of its concentration is critical for diagnosing neurological disorders. With their tunable pore structures and ultrahigh specific surface area, MOFs are an ideal candidate for electrochemical DA sensing. However, their inherent poor electrical conductivity and insufficient structural stability remain the major bottlenecks hindering practical application. In this study, a two-dimensional hollow leaf-structured ZIF-PDA-Fe composite was successfully constructed through a synergistic strategy of polydopamine (PDA) modification and iron (Fe) doping. Subsequently, a short (10 min) dielectric barrier discharge (DBD) plasma treatment was applied to enhance its electrochemical DA sensing performance. Characterizations revealed that the DBD-treated ZIF-PDA-Fe-10 not only retained the original crystalline and morphological structure but also exhibited a significant increase in the content of surface Fe O and Zn O functional groups. Notably, a 55.7% reduction in charge transfer resistance (Rct) was achieved, indicating a marked acceleration of electron transfer kinetics. The preserved hollow porous framework, combined with the functionally modified surface, further facilitated DA mass transport-collectively contributing to a synergistic enhancement of the electrochemical response. The resulting sensor demonstrated a wide linear detection range for DA (1–400 μM) with a low detection limit of 0.93 μM. It also showed excellent selectivity against interfering substances (ascorbic acid and uric acid) and maintained 80% signal stability over 100 continuous cycles, outperforming conventional pyrolysis-derived counterparts. This work thus provides a novel strategy for the surface engineering of MOF-based electrochemical sensors.