Oxygen Self‐Supplied Nanoplatform for Enhanced Photodynamic Therapy against Enterococcus Faecalis within Root Canals

Abstract The successful treatment of persistent and recurrent endodontic infections hinges upon the eradication of residual microorganisms within the root canal system, which urgently needs novel drugs to deliver potent yet gentle antimicrobial effects. Antibacterial photodynamic therapy (aPDT) is a promising tool for root canal infection management. Nevertheless, the hypoxic microenvironment within the root canal system significantly limits the efficacy of this treatment. Herein, a nanohybrid drug, Ce6/CaO 2 /ZIF‐8@polyethylenimine (PEI), is developed using a bottom‐up strategy to self‐supply oxygen for enhanced aPDT. PEI provides a positively charged surface, which enables precise targeting of bacteria. CaO 2 reacts with H 2 O to generate O 2 , which alleviates the hypoxia in the root canal and serves as a substrate for Ce6 under 660 nm laser irradiation, leading to the successful eradication of planktonic Enterococcus faecalis ( E. faecalis) and biofilm in vitro and, moreover, the effective elimination of mature E. faecalis biofilm in situ within the root canal system. This smart design offers a viable alternative for mitigating hypoxia within the root canal system to overcome the restricted efficacy of photosensitizers, providing an exciting prospect for the clinical management of persistent endodontic infection.