Self-releasing reactive oxygen species based on metal-to-MOF charge transfer effect boosts electrochemiluminescence

Abstract

Traditional luminol-based electrochemiluminescence (ECL) systems rely on hydrogen peroxide as a co-reactant, but its limited solubility restricts luminescence efficiency and detection accuracy. Herein, a core-shell spherical zinc-based metal-organic framework (Zn-MOF) that leverages its metal-to-MOF charge transfer (MMCT) properties to autonomously generate reactive oxygen species (ROS). The zinc core serves as an electron reservoir, facilitating electron injection into the MOF shell via MMCT, enabling ROS generation without exogenous oxidants. This mechanism enhances ECL signal of luminol-derived carbon dots (L-CDs) through ROS-mediated pathways. Integrating L-CDs with Zn-MOF creates a unique reaction environment that shortens the reaction distance between L-CDs and ROS and stabilizes the intermediate active species of L-CDs, thereby improving ECL signal strength and stability in neutral environment. The system also incorporates the specific binding of ochratoxin A to its aptamer, releasing activated DNA to trigger CRISPR/Cas12a-mediated cleavage of single-stranded DNA (ssDNA) anchored to magnetic beads and dopamine (DA). After magnetic separation, DA-ssDNA is modified on the electrode surface to suppress the initial ECL response. This sensing platform offers a robust solution for detecting mycotoxins in complex matrices, with applications in food safety and environmental monitoring.