On-Site Generation of Coreactant on a Solid-State Electrochemiluminescence Electrode for Label-Free Detection of Enterohemorrhagic <i>Escherichia coli</i> in Raw Meat Samples

Rapid and accurate detection of trace microbial pathogens is essential for human health, environmental monitoring, and food safety. Here, we report the development of a solid-state electrochemiluminescence (ECL) bacterial sensor based on a β-glycosidase (β-Gal)-triggered coreactant generation strategy. Leveraging a three-dimensional TiO₂ nanotube array integrated with peroxidase-like MIL-53(Fe), glucose oxidase-like Au nanoparticles, and luminol, this sensor efficiently generates coreactants on-site, enabling sensitive glucose detection. As glucose is the primary product of β-Gal-catalyzed lactose hydrolysis, its concentration directly correlates with β-Gal enzymatic activity, thus allowing for the quantification of β-Gal via ECL signal intensity. Using enterohemorrhagic <i>Escherichia coli</i> (<i>EHEC</i>) as a model of food-borne pathogens, the sensor demonstrates rapid detection (30 min) with an ultralow LOD (0.8 CFU mL^-1), representing the most sensitive label-free bacterial ECL sensor reported to date. Furthermore, the ECL electrode was applied for the detection of <i>EHEC</i> on raw salmon slices, underscoring its potential for food safety monitoring.