Bionic nanocoating-mediated near-infrared persistent luminescence photodynamic system for the treatment of periprosthetic joint infection.

Periprosthetic joint infection (PJI) is a catastrophic complication of arthroplasty, notoriously difficult to treat due to bacterial biofilms and escalating antibiotic resistance. To address this, we designed a smart, biomimetic photodynamic coating (PL-PS@Ti) for titanium implants, utilizing near-infrared persistent luminescence nanoparticles (NLPLNPs) to achieve deep-tissue, on-demand antibacterial and osteogenic efficacy. We synthesized chromium/europium-doped zinc gallate NLPLNPs coated with dendritic mesoporous silica and conjugated with a silicon phthalocyanine photosensitizer (ZGO NP@DMSN-Si-Pc, or PL-PS). A copper-coordinated polyphenol network anchored these nanocomposites to titanium substrates. We evaluated the acid-responsive singlet oxygen (1O₂) generation and 808 nm-reactivable afterglow of the coating, followed by validation in cell cultures and a rat PJI model. The acidic PJI microenvironment triggered robust 1O₂ generation, which was sustained by periodic 808 nm excitation. In vitro, the coating was highly biocompatible and achieved a 99.5% bactericidal rate. In the rat PJI model, 808 nm activation effectively cleared periprosthetic bacteria and resolved local inflammation. The coating also promoted osseointegration, yielding a bone volume fraction (BV/TV) of 20.66% at the implant interface four weeks post-treatment. The PL-PS@Ti nanocoating provides a microenvironment-responsive, antibiotic-free strategy to manage implant infections. By utilizing reactivable persistent luminescence, it bypasses the thermal damage risks of continuous irradiation. This dual capacity for broad-spectrum bactericidal activity and bone regeneration offers a practical and translatable intervention for arthroplasty-associated infections.