A mannose-functionalized carbon dot and boronic acid-graphene oxide nanocomposite fluorescent probe for Salmonella...

Current detection methods for S. typhimurium often suffer from lengthy procedures, significant technical limitations, high probe costs, and poor long-term storage stability. Herein, an "on-off-on" fluorescent probe is developed based on mannose-lectin recognition for the rapid and quantitative detection of S. typhimurium. The probe utilizes mannose-grafted carbon dots (g-CDs-M), which specifically recognize S. typhimurium through interaction with lectins on its surface. Fluorescence quenching between g-CDs-M and boronic acid-functionalized graphene oxide (GO-PBA) formed the S. typhimurium-sensing probe g-CDs-M/GO-PBA. Grafting of mannose reduced the dissociation constant between g-CDs-M and lectin Con A from 25.4 μM (g-CDs-Con A) to 0.665 μM. This sensor exhibits a linear dynamic range from 10² to 10⁷ CFU per mL with a LOD of 117 CFU per mL. Offering accuracy, simplicity, low cost, and excellent long-term storage stability, this fluorescent sensor demonstrates significant potential for applications in S. typhimurium detection.