Boosted anodic electrochemiluminescence from blue-emissive sulfur quantum dots and its bioanalysis of glutathione

Abstract

Herein, a facile top-down approach and a post-synthetic etching strategy were reported to prepare high-quality sulfur quantum dots (H-SQDs), which were first discovered with a boosted anodic electrochemiluminescence (ECL) emission in an aqueous solution. Elaborate investigations demonstrated that the significantly improved ECL properties of H-SQDs were attributed to the reduced size for inherent brightness, the highly passivated surface, and enhanced charge injection/transfer capacities after the post-synthetic hydrogen peroxide etching. The underlying anodic ECL mechanism and the redox nature of H-SQDs were studied in detail for the first time, indicating a direct oxidation ECL mechanism with tri-n-propylamine as the “oxidation-reduction” coreactant. Beyond that, the as-obtained H-SQDs also featured low cost, remarkable monodispersity, excellent water-solubility, and good biocompatibility, illustrating their great potential in ECL bioanalysis. As a proof-of-concept, H-SQDs, an emerging ECL emitter with high ECL efficiency, was utilized to construct an “off-on” ECL biosensor for sensitive glutathione (GSH) assay. This work not only promotes the exploration of novel ECL emitters, but also provides a new perspective for the application of SQDs-based ECL biosensor in clinical diagnosis.