Coordination-Driven Electrodeposition of Chitosan-Cu2+/SWCNT Hydrogel for Enhanced Non-Enzymatic Glucose Sensing

A non-enzymatic glucose sensor was fabricated via a straightforward, single-step, coordination-driven in situ electrodeposition of a chitosan–Cu2+ hydrogel. This method utilizes electrochemically generated Cu2+ ions, which directly coordinate with the amine (–NH2) and hydroxyl (–OH) functional groups of chitosan chains to form a uniform, catalytically active matrix. Electrochemical analysis using the Lingane equation quantified the coordination environment, yielding a high stability constant (Ks = 7.04 × 104) and a fractional coordination number (j = 0.67). Atomic force microscopy (AFM) revealed that the hydrogel porosity varied with chitosan concentration, while Fourier-transform infrared spectroscopy (FT-IR) confirmed strong Cu2+ coordination with chitosan’s functional groups. The resulting hydrogel acts as a robust scaffold, effectively immobilizing the Cu2+/Cu3+ redox couple, which serves as the active center for glucose electrooxidation. An optimized sensor, integrated with single-walled carbon nanotubes (SWCNTs) to enhance charge transport, demonstrated excellent analytical performance, achieving a low detection limit of 11.9 μM and high selectivity. This work presents a simple, cost-effective, and stable electrochemical sensing platform with significant potential for non-enzymatic diagnostics.