Urchin-like Fe 3 O 4 @Bi 2 S 3 Nanospheres Enable the Destruction of Biofilm and Efficiently Antibacterial Activities.

Biofilm-associated infections (BAIs) have been considered a major threat to public health, which induce persistent infections and serious complications. The poor penetration of antibacterial agents in biofilm significantly limits the efficiency of combating BAIs. Magnetic urchin-like core-shell nanospheres of Fe 3 O 4 @Bi 2 S 3 were developed for physically destructing biofilm and inducing bacterial eradication via reactive oxygen species (ROS) generation and innate immunity regulation. The urchin-like magnetic nanospheres with sharp edges of Fe 3 O 4 @Bi 2 S 3 exhibited propeller-like rotation to physically destroy biofilm under a rotating magnetic field (RMF). The mild magnetic hyperthermia improved the generation of ROS and enhanced bacterial eradication. Significantly, the urchin-like nanostructure and generated ROS could stimulate macrophage polarization toward the M1 phenotype, which could eradicate the persistent bacteria with a metabolic inactivity state through phagocytosis, thereby promoting the recovery of implant infection and inhibiting recurrence. Thus, the design of magnetic-driven sharp-shaped nanostructures of Fe 3 O 4 @Bi 2 S 3 provided enormous potential in combating biofilm infections.