Electrochemical nanosensors using MXene-carbon dot modified screen-printed carbon electrodes for creatinine detection in serum samples

Abstract

An innovative electrochemical (EC) nanosensor utilizing screen-printed carbon electrodes (SPCEs) functionalised with MXenes (Ti₃C₂T_X) and carbon dots (CDs) has been developed for the ultrasensitive sensing of creatinine in phosphate-buffered saline (PBS) and human serum samples. This novel SPCE@MXene@CDs configuration significantly enhanced redox signals, achieving excellent sensitivity with a 0.016 mg dL⁻¹ detection limit. The electrical conductivity of the SPCE@MXene@CDs sensor was enhanced by systematically optimizing four key parameters: scan rate, number of scan cycles, pH of the PBS buffer, and CD concentration during fabrication. The nanosensor demonstrated outstanding selectivity with no interference from common metabolites (e.g., glucose, urea, ascorbic acid, glutathione, bovine serum albumin, globulin, bilirubin, gentamicin, vancomycin, arginine, and histidine) and electrolytes (Ca²⁺, Mg²⁺, PO₄³⁻, and SO₄²⁻). Additionally, the nanosensor demonstrated a high correlation with the standard Jaffe method (R² = 0.99) for creatinine detection in ultra-low serum volumes of 5 µL (n = 89). The nanosensor exhibited remarkable stability, retaining 97.8% of its initial response after 15 days, along with excellent reproducibility confirmed by overlapping cyclic voltammetry cycles, underscoring its reliability for practical creatinine detection. Our research findings underscore the potential of this nanosensor for rapid, highly sensitive, and point-of-care creatinine monitoring in complex biological environments.