A Chalcone-based Fluorescent Responsive Probe for Selective Detection of Nitroreductase Activity in Bacteria

A new chalcone-based fluorescent turn-on probe (3c) responsive to nitroreductase (NTR) activity and its application toward the detection of bacteria are presented. The probe exhibits turn-on fluorescence at 535 nm in response to NTR activity and its optical changes are resulted from the NTR-mediated reduction of the aromatic nitro group to aniline, leading to fluorescence enhancement due to the push–pull effect of the structure. The detection capability and mechanism of the probe for NTR activity are thoroughly investigated. Probe 3c exhibited an excellent detection ability toward NTR activity with high selectivity and low background signal. Lastly, 3c was applicable for identifying infectious bacteria including the ESKAPE pathogens using a wash-free process owing to the turn-on fluorescent signal in response to bacterial NTR activity.