A PCR-enhanced UCNPs-WS2 fluorescence biosensor via dual quenching-dual recovery mechanism for rapid detection of Salmonella typhimurium

Foodborne illnesses caused by Salmonella rank first among bacterial foodborne diseases, representing a significant risk to public health and food safety, which necessitates the development of rapid and sensitive detection technologies. This study developed an upconversion‑tungsten disulfide PCR fluorescence sensor based on a “dual quenching-dual recovery” mechanism for the detection of Salmonella typhimurium ( S. typhimurium ). By utilizing the dual properties of tungsten disulfide, which include peroxidase-like activity and high fluorescence quenching efficiency, the sensor establishes a quantitative correlation between the upconversion fluorescence signal and S. typhimurium concentration, following target-specific signal amplification via PCR. The constructed method demonstrated good specificity and repeatability, with a detection limit as low as 22.5 CFU/mL. Furthermore, by reducing the number of PCR cycles by approximately 12 (from 34 to 22), the detection time was shortened by about 24 min while achieving a detection limit comparable to that of qPCR. The sensor performed excellently in real food matrices (chicken, eggs, fish), showing spike recovery rates of 92.0%–106.3% and relative standard deviations below 10%. In summary, the upconversion fluorescence biosensing strategy integrated with PCR amplification presented in this study provides a highly sensitive, rapid, and reliable solution for the pathogen detection, significantly enhancing the capacity for prevention and control of foodborne diseases.