Cu-mediated tetrathiomolybdate framework for ultrasensitive non-enzymatic creatinine sensing in human serum

Creatinine (CRT) is a key biomarker for diagnosing, staging, and monitoring renal dysfunction, particularly in the early diagnosis of chronic kidney disease (CKD). Herein, we present the development of a novel non-enzymatic electrochemical biosensor for the CRT detection with high specificity and sensitivity. The synergistic incorporation of Cu within the thiomolybdate framework (MoS 4 2− ) yields a structurally stable material, Cu 2 MoS 4 (CMS), with enhanced electrocatalytic activity and high selectivity toward CRT. X-ray photoelectron spectroscopy (XPS) confirms the insertion of Cu in the MoS 4 2− framework, while transmission electron microscopy (TEM) reveals the nanosheet morphology of CMS. The electrocatalytic performance of the CMS/nafion-modified glassy carbon electrode (GCE) toward CRT detection was systematically evaluated through a range of electroanalytical techniques. The developed CRT biosensor exhibited a rapid response time (<50 s), excellent reproducibility with a relative standard deviation (RSD) of 1.40% ( n = 6) and exhibits strong selectivity against commonly encountered interferents such as uric acid, glutathione, dopamine, ascorbic acid, glucose, L-cysteine, thiourea, glycine, and urea. Linear analytical response of the sensor over expanded detection range of CRT concentration from 10.0 to 1000.0 nM was recorded, and a low limit of detection (LOD) of 4.16 nM (differential pulse voltammetry) and 0.8 nM (chronoamperometry) was achieved. The sensor exhibited robust storage stability with negligible signal degradation, along with excellent reproducibility. Finally, the sensor is deployed for the detection of CRT in human serum, thereby demonstrating a potential candidate for future point-of-care (POC) routine CRT monitoring.