Biomimetic Engineering of Robust Gradient Antibacterial Coatings using Hollow Nanoframes of Prussian Blue Analogues

Photothermal therapy for bacterial infections poses a significant challenge due to the high temperatures required for effective bacterial eradication, which can also harm surrounding healthy tissues. Determining the minimal effective temperature for bacterial destruction is therefore critical. In this study, artificial reef-like manganese-doped Prussian blue (PBMn) nanoframes are developed as photothermal agents and physical cross-linkers to reinforce a phytic acid and cationic polymer network coating. This innovative deposition approach facilitates the creation of a gradient PBMn-enhanced phytic acid-cationic polymer (PC-PBM) coating, achieving a balance between effective photothermal antibacterial activity and reduced heat-induced collateral damage. When applied to a polyurethane (PU) substrate, the gradient PC-PBM coating exhibits excellent photothermal efficiency, biocompatibility, and tunable antibacterial activity. Gene transcriptomics analysis demonstrates significant downregulation of virulence genes and biofilm-forming genes in pathogens following PC-PBM treatment, confirming the antibacterial efficacy of the coating. Both in vitro and in vivo evaluations, including studies in an infected hernia model, underscore the coating's excellent anti-infection performance. This work introduces a robust and biomimetic strategy for constructing gradient coating, advancing photothermal therapy by achieving effective bacterial eradication with reducing collateral damage to healthy tissues.