A novel non-enzymatic creatinine sensor for detection in human urine via analyte-responsive one-step electrodeposition and electrochemical sensing (OS-EES)

Abstract

This study reports a proof-of-concept non-enzymatic electrochemical sensor for creatinine detection based on a novel analyte-responsive approach, termed one-step electrodeposition and electrochemical sensing (OS-EES). In this strategy, Pd–Cu bimetallic nanoparticles (NPs) are electrodeposited in simply processed real urine samples, allowing direct interaction between creatinine and highly active NPs during deposition. This drives in-situ formation of Pd–Cu–creatinine complexes, which alter the electrode's surface structure and electrochemical behavior, resulting in distinct oxidation currents. The sensor exhibits a wide, clinically relevant linear detection range of 0–452 mg/dL added creatinine in real urine, covering normal and elevated urinary creatinine levels, with RSD below 2.2% and a limit of detection (LOD) of 13.54 mg/dL, supporting reliable quantification in real urine samples of varying color and pH (5.3–6.4) with minimal sample preparation, including filtration and standardized dilution. Mechanistic insights show enhanced performance arises from early-stage interaction, synergistic Pd–Cu effects, preferential creatinine binding at Pd-rich sites, and amplification by residual Pd²⁺/Cu²⁺ ions. Importantly, OS-EES demonstrates feasibility in real urine, integrating fabrication and sensing into a single electrochemical run to provide a rapid, versatile, and reliable platform for creatinine monitoring via simplified sample handling. Beyond creatinine, this analyte-responsive approach may be extended to other analytes and metallic-based systems, opening new opportunities for next-generation electrochemical sensors in practical analytical applications.