On–Off–On Gold Nanocluster-Based Fluorescent Probe for Rapid Escherichia coli Differentiation, Detection and Bactericide Screening

The bacterial differentiation, detection and bactericide screening are critical for environmental monitoring and human health maintenance. In this work, we present a novel strategy for rapid Escherichia coli (E. coli) differentiation, detection and bactericide screening, by employing an on–off–on gold nanocluster (AuNC)-based fluorescent probe. We demonstrate that by hijacking their copper-binding and redox pathways to capture and reduce Cu2+, E. coli bacteria can selectively and efficiently recover the fluorescence of AuNC from Cu2+-caused quenching. Based on this on–off–on AuNC-based fluorescent probe, rapid differentiation and detection of E. coli bacteria in artificial contaminated water sample with trace concentration of bacteria (around 100 CFU/mL) is successfully realized within 0.5 h, showing great potential for rapid point-of-care detection of pathogenic E. coli bacteria in environmental monitoring and clinical bedside diagnosis. Furthermore, this on–off–on AuNC-based fluorescent probe can enable rapid and accurate bactericide screening test for multidrug-resistant E. coli in sepsis blood sample, which is greatly helpful to accelerate the pace of treatment and reduce the mortality of infectious diseases.