The commercial antibiotics with inherent AIE feature: In situ visualization of antibiotic metabolism and specifically differentiation of bacterial species and broad-spectrum therapy

The research on pharmacology usually focuses on the structure-activity relationships of drugs, such as antibiotics, to enhance their activity, but often ignores their optical properties. However, investigating the photophysical properties of drugs is of great significance because they could be used to in situ visualize their positions and help us to understand their working metabolism. In this work, we identified a class of commercialized antibiotics, such as levofloxacin, norfloxacin, and moxifloxacin (MXF) hydrochloride, featuring the unique aggregation-induced emission (AIE) characteristics. By taking advantage of their AIE feature, antibiotic metabolism in cells could be in situ visualized, which clearly shows that the luminescent aggregates accumulate in the lysosomes. Moreover, after a structure-activity relationship study, we found an ideal site of MXF to be modified with a triphenylphosphonium and an antibiotic derivative MXF-P was prepared, which is able to specifically differentiate bacterial species after only 10 min of treatment. Moreover, MXF-P shows highly effective broad-spectrum antibacterial activity, excellent therapeutic effects and biosafety for S. aureus-infected wound recovery. Thus, this work not only discovers the multifunctionalities of the antibiotics but also provides a feasible strategy to make the commercialized drugs more powerful.