A fluorescence sensing array based on photonic crystals and RAA for sensitive and high-throughput detection of Salmonella in foods

Salmonella can cause serious foodborne diseases, which is a major concern for global public health. The sensitive and fast analysis of Salmonella is of importance for food safety. Herein, we developed a fluorescence sensing array based on photonic crystals (PCs) and recombinase-aided amplification (RAA) for high-throughput and high-sensitive analysis of Salmonella in foods. In this assay, RAA was employed for powerful amplification of the target DNA of Salmonella, and the generated dsDNA amplicon was embedded with nucleic acid dye SYBR Green I (SGI), emitting fluorescence. Furthermore, the fluorescence signal was physically enhanced by PCs array; meanwhile, the high-throughput and sensitive detection was realized by microplate reader. Because of the isothermal reaction and lyophilized regent of RAA, the proposed array possessed gentle operation and stable amplification performance. Besides, a small volume of loading samples with 2 μL was required on the PCs array for powerful fluorescence enhancement. Due to the synergistic signal amplification effect of RAA and photonic crystals, a low limit of detection (LOD) of 10 CFU/mL was achieved. Besides, the proposed array exhibited excellent performance with 100% accuracy in 20 spiked food samples. Therefore, the proposed method with the advantages of sensitivity and high throughput showed great application potential.