An ultrasensitive fluorescence nano-biosensor based on RBP 41-quantum dot microspheres for rapid detection of Salmonella in the food matrices.

Swift screening of Salmonella-contaminated food is crucial for timely prevention and control of foodborne illness outbreaks. A novel phage receptor binding protein (RBP 41) was previously identified and characterized from phage T102. This study functionalized RBP 41 onto magnetic beads (MBs) and quantum dot microspheres (QDMs) to form magnetic separation and fluorescent probes, respectively. The bacteria were captured by RBP 41-MBs and labelled with RBP 41-QDMs to form MBs-RBP 41-bacteria-RBP 41-QDMs complexes, then the fluorescence intensity of complexes was detected for determination of Salmonella. This proposed biosensor was demonstrated to detect Salmonella as low as 0.1245 Log10 CFU/mL (∼2 CFU/mL) within ∼1.5 h. The recovery yield of Salmonella in the spiked food samples ranged from 87 % to 119 %, indicating that it could detect Salmonella in real samples. This novel magnetic fluorescence nano-biosensor has potential to detect the bacteria in the different sample to reduce the detection time and increase sensitivity.