Light-mediated activation of nitric oxide and antibacterial polymers for anti-biofilm applications

Bacterial biofilms remain a major challenge in treating persistent infections due to their dense extracellular matrix and inherent antibiotic resistance. Herein, we propose a light-responsive nanoparticle system (PNO@Ir) that integrates a nitric oxide (NO) donor polymer (PNO) with the photosensitizer fac-Ir(ppy)₃. Upon green light irradiation, NO release and activation of primary amine-containing antibacterial polymers are triggered via a dual mechanism involving triplet-triplet energy transfer (TTET) and photoinduced electron transfer (PeT). Under mildly acidic and hypoxic conditions, protonation of the exposed amines induces nanoparticle reorganization, leading to surface charge reversal and enhanced bacterial affinity. Both in vitro and in vivo studies, including a murine wound infection model, demonstrate that this cascade-activation strategy disrupts methicillin-resistant Staphylococcus aureus (MRSA) biofilms. This work presents a synergistic and spatiotemporally controllable platform for NO delivery and antibacterial polymer activation, offering significant potential for combating antibiotic-resistant bacterial infections.