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

The chelation interaction between sodium lignosulfonate (SLS) and Cu²⁺ 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 Cu²⁺ 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 Cu²⁺, 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-Cu²⁺ coordination strategy offers a novel approach for optimizing Cu-based enzyme-free electrochemical creatinine sensors.