An osmium-modified Prussian blue heterostructure for biofilm disruption and oxidative stress to combat methicillin-resistant Staphylococcus aureus infections.

One major contributor to the therapeutic recalcitrance of methicillin-resistant Staphylococcus aureus (MRSA) infections is its robust biofilm formation, which impedes therapeutics penetration, diminishes bacterial susceptibility to exogenous stimulus and exacerbates host inflammation, collectively leading to suboptimal therapeutic outcomes. To address these interrelated challenges, we developed an osmium-modified cobalt‑iron Prussian blue analogue (OsCoPBA) heterostructure with high-affinity binding to MRSA biofilm and exceptional photothermal conversion efficiency under near-infrared (NIR) irradiation, thereby enabling effective biofilm disruption. The OsCoPBA heterostructure was characterized by its redox property, imparting both pro-oxidant and anti-oxidant capabilities under different conditions. In acidic wounds, OsCoPBA exhibited a peroxidase (POD)-like activity, generating bactericidal reactive oxygen species (ROS) to induce oxidative stress within MRSA. Conversely, during the wound healing phase, OsCoPBA exhibited robust superoxide dismutase (SOD)-like activity (a peak ·O₂- scavenging efficiency of 95% at the optimal concentration of 250 μg mL-1) and enhanced catalase (CAT)-like activity, effectively scavenging excess ROS to suppress inflammation. This heterostructure achieved on-demand regulation of ROS for meeting the antibacterial and anti-inflammatory requirements, representing a rational design strategy for managing MRSA-infected wounds.