Penicillin G acylase-responsive near-infrared fluorescent probe: Unravelling biofilm regulation and combating bacterial infections

Antibiotic resistance poses a critical threat to human healthcare, largely driven by bacterial biofilms. These biofilms resist the immune system and antibiotics, rendering enclosed microbial cells 10–1000 times more antibiotic-resistant than planktonic cells, leading to severe infections. Therefore, there is an urgent need to develop innovative tools for investigating biofilm regulators and devising novel antibacterial strategies. In this study, we developed Cy-NEO-PA, a near-infrared (NIR) fluorescent probe responsive to penicillin G acylase (PGA), with bacteria-targeting ability. This probe was designed to visualize the influence of environmental factors on biofilm formation in Acinetobacter baumannii (A. baumannii). Our findings demonstrated that glucose suppressed PGA production, leading to enhanced biofilm formation, whereas phenylacetic acid (PAA) stimulated PGA production and inhibited biofilm formation in A. baumannii. These observations highlight the remarkable capability of Cy-NEO-PA to accurately measure PGA dynamics, shedding light on the critical role of PGA in biofilm development. Additionally, Cy-NEO-PA exhibited excellent biocompatibility, potent reactive oxygen species (ROS) generation, efficient photothermal conversion, and bacteria-targeting abilities, making it a promising agent for combating bacterial infections and promoting wound healing through photothermal (PTT)/photodynamic (PDT) therapy. These discoveries emphasize the significant role of PGA in antibacterial therapy and offer valuable insights for the design of effective strategies targeting PGA to combat biofilm-associated infections.