A Galvanostatic Strategy to Modulate ECL-RET in MnO₂-Polypyrrole-Polyluminol Nanohybrids for Signal-On Sensing of...

Glutathione (GSH) plays an important role in multiple metabolic systems due to its master antioxidant nature, and its depletion is closely associated with neurodegenerative disorders. In this study, we report a facile galvanostatic strategy to modulate a solid-state electrochemiluminescence resonance energy transfer (ECL-RET) system for ultrasensitive signal-on detection of GSH. The ECL-RET platform based on a MnO₂-covered polypyrrole-polyluminol nanohybrid (MnO₂/PPy-PL)-modified GCE surface was fabricated via a simple galvanostatic method, enabling uniform deposition and shortening the donor-acceptor distance. The copolymerized polypyrrole significantly amplified the ECL emission of polyluminol owing to its high conductivity and rapid electron-transfer kinetics. MnO₂ nanoparticles (MnO₂ NPs) play an essential role in serving as an efficient ECL acceptor and enabling the signal-on sensing of GSH detection. The galvanostatic development of the ECL-RET platform and specific dissolution of MnO₂ NPs by GSH incubation were confirmed using FESEM, XPS, Raman, UV-visible DRS, and fluorescence spectroscopy. The inhibited ECL emission of MnO₂ NPs/PPy-PL/GCE gradually recovered upon incubation with the linearly increased concentration of GSH from 5 nM to 5 μM, and the calculated LOD and LOQ were 0.12 nM and 0.36 nM, respectively. The proposed sensor displays an excellent anti-interference ability and successfully demonstrates the sensing of GSH in human serum samples, which shows a good recovery percentage from 102% to 104%. The superior sensing performance of the proposed signal-on solid-state ECL-RET sensor methodology provides a promising potential for clinical diagnostics.