Fluorescent Assay for Salmonella Detection Based on Triangle Multivalent Aptamer-Initiated Catalytic Hairpin Assembly

Salmonella poses a severe global threat to food safety and public health, necessitating rapid, sensitive, and reliable detection methods. Conventional techniques often suffer from complexity, time consumption, cost, or limited sensitivity. To address this, we developed a novel enzyme-free fluorescence detection platform, termed the MTAI-CHA system, integrating magnetic nanoparticle-based triangle multivalent aptamer-initiators (MTAI) with catalytic hairpin assembly (CHA) signal amplification. The triangular DNA nanostructure contained significantly enhanced binding affinity of multivalent aptamers, increasing the sensitivity compared to monovalent aptamers. The optimized MTAI-CHA system demonstrated exceptional performance: a low detection limit of 10 CFU/mL and excellent specificity against non-target pathogens. This sensitive, specific, and robust strategy, leveraging multivalent aptamer recognition and enzyme-free signal amplification, holds significant potential for rapid pathogen screening in food safety, clinical diagnostics, and environmental monitoring, with adaptability to other targets via aptamer substitution.