Reactive Oxygen Species Responsive Nitric Oxide Release for Enhanced Photodynamic Antibacterial Therapy of Scaffolds

Photodynamic therapy (PDT) presented tremendous potential for combating implant-related infections, but its antibacterial efficacy was constrained by rapid electron–hole pair recombination of photosensitizers and barrier action of a dense biofilm on reactive oxygen species (ROS). Herein, a cascade phototherapeutic AuKN-LA nanosystem was constructed by depositing Au nanoparticles and l -arginine (LA) on potassium niobate (KN) photosensitizer. In the nanosystem, Au nanoparticles with lower Fermi levels could capture photogenerated electrons and thus suppress electron–hole pair recombination to enhance ROS generation. Especifically, l -arginine could cascade trigger by the generated ROS to release nitric oxide (NO) to destroy the biofilm, thereby facilitating the entry of ROS. Furthermore, NO itself possessed antibacterial activity, which could form synergy with PDT. Then, the nanosystem was introduced into poly( l -lactic acid) scaffolds fabricated by laser additive manufacturing. Photoelectrochemical and ROS analysis proved that the electron–hole pair separation was improved, significantly increasing ROS generation. NO detection and crystal violet staining showed that the scaffolds could effectively remove the biofilm by sustainably releasing NO under light irradiation. As a consequence, the scaffolds exhibited excellent antibacterial rates of 98.7% and 99.2% against E. coli and S. aureus, respectively, by disrupting bacterial cell membranes and causing leakage of nucleic acid molecules and proteins.