Preparation of the Cf-GQDs-Escherichia coli O157: H7 Bioprobe and Its Application in Optical Imaging and Sensing of Escherichia coli O157: H7

The food-borne diseases triggered by Escherichia coli O157: H7 ( E. coli O157: H7) have become a life-threatening problem for tens of thousands of people around the world in the past few decades. Therefore, a rapid, simple, and user-friendly biosensing label to monitor E. coli O157: H7 has become necessary and important. In this work, carboxyl functionalized graphene quantum dots (cf-GQDs) as fluorescent labels for optical imaging and sensing in E. coli O157: H7 have been firstly proposed and evaluated. E. coli O157: H7 antibody is successfully covalently conjugated to water-soluble cf-GQDs via a cross-linking reaction, and then cf-GQDs immunofluorescence probe is achieved. The probe can effectively recognize E. coli O157: H7 and generate strong fluorescent signal. The experimental result shows that the blocking agent can obviously improve the specificity of the bioprobe for E. coli O157: H7 with the minimum detection limit of 100 cfu/mL. This novel detection method could be as a useful tool to detect E. coli O157: H7 in food, water, and environment.