Discovery of environment-sensitive fluorescent probes for detecting and inhibiting metallo-β-lactamase

Metallo-β-lactamases (MβLs) hydrolyze almost all β-lactam antibiotics, including last-resort carbapenems, and is emerging as a global antibiotic resistance threat. Discovering novel fluorescent molecules for visualizing MβLs has proved challenging. Herein, based on covalent and Zn(II)-binding scaffold of MβLs inhibitor, we designed and synthesized a novel series of environment-sensitive fluorescent probes ESA, DHA and DHS, to detect and inhibit the enzymatic activity of MβLs. Of these probes, ESA is a highly active NDM-1 inhibitor (IC₅₀ = 81 nM), which exhibited excellent turn-on fluorescent properties to effectively distinguish NDM-1 (B1), ImiS (B2) and L1 (B3) in vitro. Cell imaging indicated that ESA can label and track the distribution process of the intracellular protein NDM-1 in living cells. Molecular docking further elucidated the environment-sensitive fluorescent response nature of ESA to the NDM-1. Significantly, ESA showed excellent synergistic antibacterial effect, combined with meropenem, to overcome NDM-1-mediated drug-resistant pathogens.