Identification of bacterial strains is critical for the theranostics of bacterial infections and the development of antibiotics. Many organic fluorescent probes have been developed to overcome the limitations of conventional detection methods. These probes can detect bacteria with “off-on” fluorescence change, which enables the real-time imaging and quantitative analysis of bacteria in vitro and in vivo. In this review, we outline recent advances in the development of fluorescence-based dyes capable of detecting bacteria. Detection strategies are described, including specific interactions with bacterial cell wall components, bacterial and intracellular enzyme reactions, and peptidoglycan synthesis reactions. These include theranostic probes that allow simultaneous bacterial detection and photodynamic antimicrobial effects. Some examples of other miscellaneous detections in bacteria have also been described. In addition, this review demonstrates the validation of these fluorescent probes using a variety of biological models such as gram-negative and -positive bacteria, antibiotic-resistant bacteria, infected cancer cells, tumor-bearing, and infected mice. Prospects for future research are outlined by presenting the importance of effective in vitro and in vivo detection of bacteria and development of antimicrobial agents.

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The rising emergence of multidrug-resistant bacteria is becoming an increasingly serious threat to human health, therefore the development of structurally novel drugs has been an important topic worldwide to overcome drug-resistant strains. In this work, a series of novel acylhydrazone-bridged quinazolinone imidazoles were designed, synthesized and characterized by 1 H NMR, 13 C NMR and HRMS spectra. Bioactive assays showed that some target compounds exhibited significant antimicrobial potency. Especially, octadecyl derivative 6h and 4-fluorobenzyl derivative 7i showed 2.5~3.3 folds stronger activities against bacteria S. dysenteriae and E. coli DH52 than chloramphenicol, and 28 as well as 8.4 times higher efficacies toward fungus A. flavus than clinical drug fluconazole. The DNA-targeting preliminary exploration of highly active compound 7i by UV-Vis spectroscopy revealed that imidazole derivative 7i could intercalate into calf thymus DNA to form 7i-DNA supramolecular complex and thus block DNA replication to exert powerful antibacterial activities. Molecular docking study displayed that the active molecule 7i could form hydrogen bond with DNA base. This class of compounds as new type of specific anti-A. flavus and antibacterial drugs were worthy of being deeply investigated.

Hydrogen sulfide (H2S) acts as a crucial biological and environmental component in a variety of processes. Abnormal levels of H2S endogenously generated in human body are associated with various diseases. Meanwhile, H2S gas leaked from various manufacturing environments has a fatal effect against the human body. For this reason, H2S has been considered as a potential biomarker for the diagnosis and treatment of various human diseases, and as a toxic gas that should be detected when leaked to the workplace for the safety of workers. In this study, we synthesized an azide‐containing naphthalimide derivative that can play as a fluorescence turn‐on probe for H2S.