Platinum single-atom enables synergistic enhancement in dopamine electrochemical sensing via Pt-N coordination and π-π stacking in hollow carbon nanospheres

Accurate detection of dopamine is critical for the diagnosis and monitoring of diverse neurological diseases, and electrochemical analysis, with its high sensitivity, rapid response, ease of operation, and excellent selectivity, serves as an effective approach for dopamine monitoring. In this study, a hierarchical hollow composite material, consisting of polyaniline-coated hollow carbon spheres and platinum single-atom catalysts (Pt/PANI@HCS), was developed for electrochemical dopamine sensing using a hard-template method. Firstly, silica spheres were used as templates, and hollow carbon spheres (HCS) were prepared by carbonization of phenolic resin and partial etching with alkaline solution. Then, polyaniline (PANI) was polymerized on the surface of HCS to form a conductive network. Finally, platinum single-atom catalysts (Pt SACs) were precisely loaded using a UV light-assisted reduction method. Synchrotron X-ray absorption fine structure (XAFS) analysis confirmed the formation of stable Pt-N coordination bonds in the material. Combined with Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) characterization, it revealed strong interactions between Pt and PANI. Thanks to the unique Pt-N coordination and the synergistic effect of π-π stacking, this composite material exhibited excellent electrochemical sensing performance for dopamine: a wide linear range (0.5 μM to 63 μM), low detection limit (LOD) (0.24 μM), and good anti-interference ability. Further, the recovery rates of serum sample tests ranged from 94.20% to 106.60%, confirming their application potential in actual biological sample detection. This strategy of tuning interfacial interactions opens a new avenue for designing new neurotransmitter sensors.