Mesoporous silica-encapsulated Co-doped ceria nanodots with enhanced peroxidase-like activity enable intensive and long-lasting chemiluminescence for glutathione detection

Chemiluminescence (CL) assay has been considered as a sensitive method for quantitative detection of glutathione (GSH), a significant regulatory metabolite in cells. However, most reported CL assays present flash-type CL emission with limited detection accuracy and repeatability. Herein, an intensive and long-lasting glow-type CL system was proposed based on a novel bimetallic Co-doped ceria mesoporous nanocomposite (Co-ceria@MSN), which was prepared by in-situ growth of sub-3 nm ultrasmall Co-ceria nanodots within the pore channels of mesoporous silica nanospheres (MSN). Attributing to the confinement effect of MSN and the superior peroxidase-like catalytic activity of Co-ceria nanodots, this nanocomposite could function as a nanozyme to catalyze luminol/H2O2 CL reaction, producing a robust and long-lasting CL emission with a long plateau for over 1.2 h at physiological pH. Surprisingly, both the CL intensity and duration time were found to exist a strong dependence on GSH concentration. Accordingly, the proposed glow-type CL platform was further applied for GSH determination with a limit of detection down to 10 nM. This strategy was successfully utilized for quantitative evaluation of cellular GSH levels, indicating its broad prospects in clinical diagnosis.