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

Abstract

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.