A collaborative CeO2@metal-organic framework nanosystem to endow scaffolds with photodynamic antibacterial effect

Antibacterial photodynamic therapy had attracted considerable attention in implant-associated infections treatment due to its high selectivity and no resistance. Actually, bacteria readily formed protective biofilm to cover themselves and impede the permeation of photosensitizers , severely impairing the therapeutic effect. Herein, a collaborative nanosystem was constructed by in-situ growing cerium oxide (CeO 2 ) nanoparticles on porphyrinic metal-organic framework PCN-224, and then mixed with poly- l -lactic acid (PLLA) powder to fabricate CeO 2 @PCN-224/PLLA scaffold. In the nanosystem, CeO 2 was expected to disrupt the biofilm integrity by releasing Ce 4+ , exposing bacteria. Subsequently, PCN-224 could grab this opportunity to kill the bacteria by generating reactive oxygen species (ROS) under light irradiation, thereby achieving the desired antibacterial effect. Crystal violet staining and agarose gel electrophoresis results demonstrated that the bacterial biofilm was effectively eliminated by cleaving the extracellular DNA chains. Coomassie brilliant blue and acridine orange staining revealed that the generated ROS effectively killed bacteria by destroying their cell membrane , causing DNA hydrolysis and protein leakage. Furthermore, ROS could also weaken the antioxidant capacity of bacteria by consuming their glutathione, further accelerating bacterial death. As a consequence, the scaffolds presented a robust antibacterial rate of 97% against S . aureus . Collectively, this work provides a promising strategy for efficient implant-related infection treatment.