Cu nanoparticles regulated by sodium lignosulfonate-Cu2+ chelation for highly sensitive non-enzymatic creatinine sensing

The chelation interaction between sodium lignosulfonate (SLS) and Cu 2+ is exploited to construct an enzyme-free creatinine sensing electrode (SLS-Cu/SPCE) via one-step electrodeposition on screen-printed carbon electrodes (SPCE). SLS chelation moderates Cu 2+ electro-reduction kinetics, resulting in finely structured Cu particles with a uniform and dense distribution. These Cu particles, with abundant unsaturated coordination sites, enhance creatinine adsorption and promote specific complexation with Cu 2+ , thereby increasing the oxidation current response for sensitive detection. The SLS-Cu/SPCE achieved a 0.12 µM detection limit, a 10–300 µM linear range, high reproducibility, and long-term stability over 28 days. Tests in human urine samples showed good agreement with enzymatic assays (relative error < 16%). The SLS-Cu 2+ coordination strategy offers a novel approach for optimizing Cu-based enzyme-free electrochemical creatinine sensors. Graphical A sodium lignosulfonate-Cu 2+ chelation strategy produces refined copper particles on SPCE with abundant unsaturated sites. These sites enhance creatinine adsorption and Cu 2+ complexation, enabling highly sensitive non-enzymatic detection (0.12 μM LOD, 10-300 μM range) with strong anti-interference and excellent stability.