Ultrasensitive detection of glutathione using CNs@Cr/g-C3N4 nanocomposite electrochemiluminescence in the presence of Cu2+

Background Glutathione (GSH) serves as a pivotal antioxidant within biological systems. Dysregulated GSH levels are associated with a spectrum of pathologies, including carcinogenesis, hepatic dysfunction, and neurodegenerative disorders. Developing robust GSH detection methodologies is essential for assessing cellular health, facilitating early diagnosis of disease states, and tracking therapeutic efficacy. Electrochemiluminescence (ECL), which integrates electrochemical reactions with luminescent output, offers low background noise, making it highly suitable for biomolecule analysis. ECL-based GSH assays employing advanced nanomaterials are anticipated to amplify signals at low GSH concentrations, thereby playing a critical role in clinical diagnostics and biochemical research. Results This study presents a novel ECL sensor for the ultrasensitive detection of GSH, utilizing chromium/g–C 3 N 4 –loaded carbon nanospheres (CNs@Cr/g-C 3 N 4 ) composites. Carbon spheres (CNs) and chromium (Cr) can improve the ECL properties of g-C 3 N 4 . However, the ECL signal of CNs@Cr/g-C 3 N 4 is quenched (off-state) due to complex formation with Cu 2+ . Upon GSH addition, the higher coordination affinity between GSH and Cu 2+ partially restores the ECL signal of g-C 3 N 4 (on-state), allowing for quantitative GSH detection. Under optimized conditions, the linear detection range for GSH extends from 5.0 × 10 −9 to 1.0 × 10 −4  M with a limit of detection (LOD) of 3.3 × 10 −10  M (S/N = 3), alongside high selectivity, stability, and reproducibility. More notably, the as-proposed ECL sensor was successfully applied to the quantification of GSH in real drug samples with excellent recovery rates. Signifiance In contrast to traditional techniques for GSH detection, our approach involves a one-time chemical modification of the electrode, eliminating the need for complex probe immobilization steps and streamlining the detection process. Besides, this “off-on” ECL sensing strategy, leveraging Cu 2+ and CNs@Cr/g-C 3 N 4 , offers an innovative approach for developing advanced sensing systems. And this method is user-friendly, cost-effective, holding significant potential for applications in clinical diagnostics and pharmaceutical analysis.