Colorimetric/fluorescent dual-mode biosensor for Staphylococcus aureus based on inner filter effect between AuNPs and Si/CsPbBr3 quantum dot materials.

Staphylococcus aureus (S. aureus), a prevalent foodborne pathogen, poses a serious threat to human health, highlighting the urgent need for reliable and sensitive detection methods. Given the limitations of single-mode sensors such as false positives/negatives, a colorimetric and fluorescent dual-mode biosensor based on quantum dot material was proposed for the evaluation of S. aureus in food. This sensor utilized CsPbBr3@SiO2 quantum dots as a stable fluorescent probe. The sensing mechanism relies on the inner filter effect, where gold nanoparticles effectively quench the fluorescence of CsPbBr3@SiO2, enabling rapid and highly sensitive biosensing. Under optimized conditions, the biosensor achieved a broad detection range of 1 to 106 colony-forming unit/mL (CFU/mL), with low detection limits of 103 CFU/mL for colorimetric mode and 0.54 CFU/mL for fluorescent mode. It also exhibited excellent selectivity and was successfully applied to analyze various food samples. This study demonstrates perovskite nanomaterials as a visual tool for detecting foodborne pathogens in complex matrices.