Biofilm Homeostasis Interference Therapy via 1O2‐Sensitized Hyperthermia and Immune Microenvironment Re‐Rousing for Biofilm‐Associated Infections Elimination

Abstract The recurrence of biofilm‐associated infections (BAIs) remains high after implant‐associated surgery. Biofilms on the implant surface reportedly shelter bacteria from antibiotics and evade innate immune defenses. Moreover, little is currently known about eliminating residual bacteria that can induce biofilm reinfection. Herein, novel “interference‐regulation strategy” based on bovine serum albumin–iridium oxide nanoparticles (BIONPs) as biofilm homeostasis interrupter and immunomodulator via singlet oxygen ( 1 O 2 )‐sensitized mild hyperthermia for combating BAIs is reported. The catalase‐like BIONPs convert abundant H 2 O 2 inside the biofilm‐microenvironment (BME) to sufficient oxygen gas (O 2 ), which can efficiently enhance the generation of 1 O 2 under near‐infrared irradiation. The 1 O 2 ‐induced biofilm homeostasis disturbance (e.g., sigB, groEL, agr‐A, icaD, eDNA) can disrupt the sophisticated defense system of biofilm, further enhancing the sensitivity of biofilms to mild hyperthermia. Moreover, the mild hyperthermia‐induced bacterial membrane disintegration results in protein leakage and 1 O 2 penetration to kill bacteria inside the biofilm. Subsequently, BIONPs‐induced immunosuppressive microenvironment re‐rousing successfully re‐polarizes macrophages to pro‐inflammatory M1 phenotype in vivo to devour residual biofilm and prevent biofilm reconstruction. Collectively, this 1 O 2 ‐sensitized mild hyperthermia can yield great refractory BAIs treatment via biofilm homeostasis interference, mild‐hyperthermia, and immunotherapy, providing a novel and effective anti‐biofilm strategy.