A Convenient Ratiometric Fluorescent Probe Based on Gold Nanoclusters and Carbon Dots for Escherichia coli Determination

Escherichia coli, as a prevalent foodborne pathogen, can harm people health seriously. Hence, developing the effective methods for E. coli determination is vital. In the paper, a convenient hybridization ratiometric fluorescent probe was constructed for the prompt determination of E. coli based on red emissive gold nanoclusters (AuNCs) and blue carbon dots (bCDs). The relevant experimental conditions were systematically optimized including copper concentration, incubation temperature, and time, in order to obtain the optimal results. There existed a strong linear relationship between the fluorescence intensity ratios (I₆₃₀/I₄₅₀) and the concentrations of E. coli for both AuNCs and bCDs. Based on the determination, it was found that the linear concentration range spanned from 10³ to 10⁷ CFU mL⁻¹, with a low limit of detection (LOD) of 120 CFU mL⁻¹. This method based on the mechanism of copper cocatalysis presents a sensitive and convenient strategy for E. coli determination, and has a promising future in the field of food safety.