Cascade catalytic self-supply of •OH coreactants enabled by GOx/Mn/Co-MOF hybrids for enhanced electrochemiluminescence sensing of miRNA-222.

In conventional electrochemiluminescence (ECL) sensing systems, the use of H2O2 as a coreactant often suffers from poor stability, susceptibility to decomposition, and weak reproducibility. Accordingly, constructing cascade autocatalytic reactions to in-situ generate hydroxyl radicals (•OH) is of great significance. Here, we developed a strategy based on the cascade catalytic self-supply of a •OH coreactant to enhance ECL sensing for miRNA-222, achieved via a cascaded self-feedback circuit and catalytic hairpin assembly (CHA). Specifically, a ternary hybrid nanozyme comprising highly dispersed manganese species and glucose oxidase (GOx) anchored on a hollow-structured cobalt metal-organic framework (GOx/Mn/Co-MOF) was constructed to catalyze glucose for the generation of •OH. The resulting •OH reacted with luminol-functionalized gold nanoparticles (L-Au NPs) to yield amplified ECL emission. Impressively, the integration of the cascaded self-feedback circuit and CHA enabled an efficient DNA cascade reaction, realizing remarkable tandem signal amplification and further enhancing the detection sensitivity for miRNA-222. As a result, the constructed biosensor achieved the detection of miRNA-222 over a wide linear range from 100 aM to 100 pM, with a detection limit down to 30 aM. More importantly, this method realized the accurate analysis of miRNA-222 in serum samples, offering a reliable analytical platform for early disease screening and clinical diagnosis.