Gold nanosensor for the selective identification of Escherichia coli in foodstuff and its antibacterial ability

A promising gold nanorod sensor that demonstrated comparable antibacterial ability, selectively recognized Escherichia coli ( E. coli ), and used selenol as the recognition group was prepared and applied for foodstuff E.coli detection. We used a sulfhydryl compound linked with fluorescent dye by sulfamide bonds ( SH-NB ) to modify gold nanorods ( GNRs ) and fabricate GNRs-SH-NB that can selectively and sensitively detect selenol. Selenol group broke sulfamide bonds, causing the fluorescent dye to fall off from GNRs-SH-NB and exhibit red fluorescence, demonstrating that it can selectively identify E. coli with the unique selenoenzymes or selenoproteins in the bacterium. After the decomposition of GNRs-SH-NB , the obtained GNRs modified by N-heterocyclic sulfhydryl compounds and positively charged fluorescent dyes showed synergistic antibacterial properties. Furthermore, the photothermal effect of GNRs increased the temperature beyond the optimum temperature of E. coli and caused its maladjustment, leading to the death of the bacterium. Thus, GNRs-SH-NB exerted a considerable antibacterial effect against E. coli and accurately detected E. coli in milk, meat, and eggshell. With the low limit of detection, this novel antibacterial sensor GNRs-SH-NB provide a promising method to identify the E. coli and further utilized in food safety field initially.