NIR-II-triggered plasmonic catalysis with tip-localized enhancement: a strategy for hypoxic biofilm eradication on orthopedic implants

The utilization of light as an external stimulus to promote the generation of hot electrons in plasmonic heterostructures and thus augment their catalytic efficacy presents significant potential for bacterial biofilm eradication. However, the inefficient harnessing of photoinduced hot electrons in conventional developed strategies greatly impede their therapeutic application in bone tissues. To overcome these challenges, we herein engineered a near-infrared II (NIR-II)-triggered plasmonic catalysis, which was fabricated through the integration of gold nanobipyramids (Au NBPs) with tip-deposited platinum nanoparticles (Pt NPs), for effective elimination of hypoxic bacterial biofilms on bone implants. The strategic deposition of Pt NPs at the tip of Au NBPs (ePt-Au NBPs) not only brought the redshift of the NIR absorption peak, but also accelerated charge separation and electromagnetic field localization, which endowed the ePt-Au NBPs plasmonic heterostructures with enhanced catalytic activity. Under NIR-II laser irradiation, the plasmonic catalysis with tip-localized enhancement enabled robust generation of hydroxyl radicals (•OH), thereby facilitating the cleavage of extracellular DNA (eDNA) within biofilms, disrupting biofilm integrity, and ultimately sensitizing bacteria to thermal ablation. These attributes collectively contribute to the effective elimination of hypoxic bacterial biofilms. Furthermore, surface functionalization with RGDC peptides conferred the implant with superior biocompatibility and osteogenic integration capabilities. This rationally designed plasmonic catalysis, combining the NIR-II-triggered simultaneous production of enhanced catalytic activity and localized hyperthermia, demonstrates significant potential for translational applications in light-responsive therapeutic strategies for implant-associated infections.