Highly Sensitive Phase-Engineered Copper Sulfide Interfaces for Nonenzymatic Electrochemical Creatinine Sensing in
Srishti Verma1,2, Gorachand Dutta1
1NanoBiosensors and Biodevices Lab, School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
None:
Herein, we report for the first time the exploration of PVP-modulated copper sulfide for a high-performance electrochemical nonenzymatic sensor for noninvasive creatinine sensing. A controlled coprecipitation route in the presence of polyvinylpyrrolidone (PVP) yields phase-pure Cu7S4, while synthesis without PVP results in a heterogeneous mixture of Cu6S6, Cu7S4, and secondary phases (CuxS). Electrochemical evaluation by cyclic voltammetry demonstrates that the phase-engineered PVP-modulated Cu7S4 sensor exhibits a stable, well-defined cathodic complexation response, in contrast to CuxS-based sensor. Mechanistic understanding was further advanced through high-resolution XPS at potentials associated with redox transitions and Copper-Creatinine complexation, confirming the role of surface Cu2+ species and the C═N group of creatinine in facilitating electron transfer. The sensor demonstrated exceptional analytical figures of merit, including a wide linear range of 0-300 μM, encompassing the entire physiological and pathological range, a low detection limit of 1.196 μM, and a high sensitivity of 541.83 μA mM-1 cm-2. Furthermore, the sensor exhibited splendid specificity, effectively mitigating uric acid interference through simple 100-fold dilution, and maintained remarkable stability with a 96.68% signal retention over 26 days. Crucially, validation using clinical human urine samples showed excellent agreement with the gold standard test (P > 0.05). The PXRD, FTIR, Raman spectroscopy, UV-visible, FESEM, HR-TEM, Zeta potential, and XPS were performed for comprehensive material characterization, which revealed crucial phase engineering and functionalization influencing electrocatalytic activity. This study establishes phase-engineered PVP-modulated Cu7S4 as a robust and reproducible nonenzymatic sensing material offering mechanistic insights that can guide the design of next-generation point-of-care creatinine sensors.
