Self-Powered Wireless Galvanic ECL Platform for On-Site Glutathione Detection

In the realm of electrochemical systems for electrochemiluminescence (ECL) analysis, reliance on an external power source, whether connected directly or through a wireless energy transfer circuit, can be limiting and inconvenient. This study reveals an innovative approach using homemade galvanized Cu foam (GCF) prepared by electrodeposition of Zinc (Zn) metal on a selected or unmasked area of Cu foam functioning as both the power source and electrode. Interestingly, simple immersion of GCF in the Luminol/H₂O₂ system showed approximately 1500 times higher ECL intensity than without its presence. The formation of intermediate products and generation of reactive oxygen species (ROS) during ECL are confirmed via NMR, in situ UV-vis, Raman, and EPR. The feasibility and robustness of the proposed platform were systematically validated through control experiments with noble metal-decorated Cu foam electrodes and different cathodic materials. As a proof-of-concept experiment, the prepared GCF based ECL platform is used for on-site detection of the stress biomarker reduced glutathione (GSH) in Parkinson's disease, where it shows rapid response times and unparalleled accuracy and covers an impressive range of GSH concentrations, from 0.5 × 10^-6 to 1.6 × 10^-4 M, with a limit of detection (LOD) at 1.8 × 10^-7 M. The sensing mechanism of the ROS-scavenging behavior of GSH, leading to thiol oxidation (conversion of GSH to GSSG (oxidised GSH)) and Cu-GSH complex formation, is confirmed by UV-Vis, FT-IR, and NMR studies. The platform showed excellent practical performance with 98-102% recovery in real human urine. Interference and time-dependent ECL profile studies on various GCF electrodes further confirm the sensor's good selectivity, stability, and reproducibility. With a self-powered design, these devices eliminate the necessity for external power supplies, intricate electrochemical setups, and photomultiplier tubes (PMT), transforming their size and cost while making them accessible for scaling and miniaturization for point-of-care applications. This self-powered ECL stands at the forefront of innovation, heralding a new era of visual and ECL imaging and biosensing applications.