Molecular imprinting film and turn-on fluorescence probe working in tandem for Salmonella Typhimurium detection

Salmonella is one of the most common pathogens that cause foodborne illnesses. Rapid qualitative and quantitative detection of Salmonella Typhimurium (S. Typhimurium) is important for human health. In this study, a Förster resonance energy transfer (FRET)-based platform was proposed to activate fluorescence sensing with a bacteria-imprinted film to facilitate S. Typhimurium detection. Imprinted films with surface cavity sites that match the surface cavity sites of S. Typhimurium was prepared. The modification of the films using 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS), weakened the hydrophobicity of the films, inhibiting the nonspecific adsorption of nontarget bacteria. Copper nanoclusters and gold nanoparticles, which are good fluorescent molecular donors and acceptors, respectively, can be used to prepare fluorescence quenching-recovery probes based on FRET. The competitive binding of the bacteria to the probes enabled the restoration of fluorescence, facilitating bacteria quantification based on the fluorescence intensity. The optimized fluorescent sensor showed a linear response to S. Typhimurium concentrations in the range of 10–107 CFU/mL with a detection limit of 17.38 CFU/mL. Thus, the proposed label-free fluorescent sensor is sensitive to S. Typhimurium, showing potential applications in the detection of this pathogen as well as other foodborne pathogens in food samples.