Field-ready wireless scopoletin sensing using a nanohybrid of graphdiyne quantum dots and N-doped graphene

Scopoletin, a bioactive compound with important physiological and pharmacological effects, lacks a simple and rapid method for real-world detection. In this paper, graphdiyne quantum dots (GDYQDs) were prepared via a one-step ultrasonication method and subsequently combined with N-doped graphene (NGR). The GDYQDs/NGR composite was drop-coated onto a screen-printed electrode (SPE) to fabricate GDYQDs/NGR-modified SPEs, integrated with a portable electrochemical workstation and Bluetooth-enabled smartphone for real-time, wireless detection of scopoletin. Beyond experimental performance, density functional theory (DFT) calculations and partial density of states (PDOS) analyses were conducted for three model substrates (I: GDYQDs, II: NGR, III: GDYQDs/NGR) and three adsorption configurations (1: O–H adsorption, 2: carbonyl O toward substrate, 3: parallel π-adsorption). Adsorption energies indicate the π-adsorption configuration as the most stable across all substrates. PDOS analysis shows a pronounced downshift of the molecular p-state upon adsorption, most notably on the GDYQDs/NGR substrate, indicating stronger electronic coupling and stabilization of adsorption complexes. Collectively, these results demonstrate a cooperative GDYQDs–NGR effect that enhances scopoletin adsorption via π–π interactions and electronic coupling, providing molecular-level guidance for designing high-performance GDYQDs/NGR-based on-site electrochemical sensors.