Low-Potential Electrochemiluminescence Imaging Mediated by Oxygen Vacancy for Sensitive Analysis of Diazinon

With the prevalence of electrochemiluminescence (ECL) in bioanalysis and clinical diagnostics, the development of efficient low-potential ECL systems has emerged as a research focus. Herein, a novel coreactant acceleration approach was reported based on FeNi layered double hydroxide enriched with oxygen vacancies (FeNi-LDH-VO). The system produced notably strong ECL signals at −0.8 V when integrated with a Zr-porphyrin metal–organic framework (Zr-MOF). Mechanistic investigations revealed that the VO in the FeNi-LDH provided abundant active sites that facilitated peroxydisulfate (S2O82–) adsorption and activation, which triggers the generation of highly reactive sulfate (SO4•–) and hydroxyl (•OH) radicals. Efficient radical production played a key role in enhancing ECL output. Based on this mechanism, an ECL imaging biosensor was designed for visually detecting diazinon (DZN). In the presence of Mg2+, the DNAzyme catalyzed the site-specific cleavage of the ferrocene (Fc)-labeled strand, resulting in the release of Fc quenchers from the electrode surface and an ECL signal that is enhanced in a concentration-dependent manner. The biosensor exhibited a wide linear range (0.1 to 5.0 × 103 nM), a low detection limit (7.6 pM), and excellent specificity and repeatability, showing potential for food marker detection.