Abstract / Summary
Percutaneous pins make external fixation clinically versatile but create a persistent conduit for pin-site infection (PSI), biofilm formation, and infection-associated loosening. Here, near-room-temperature thermoelectric Ag 2 Se was integrated onto 316L Kirschner wires by Ag sputtering and room-temperature selenization. The resulting Ag 2 Se coating was adherent, corrosion-resistant and responsive to the body-to-ambient thermal gradient across percutaneous pins. Without external power input, this thermal gradient generated a Seebeck potential across Ag 2 Se-316L, accompanied by a shift in bacterial surface potential. Consistently, respiratory redox activity and intracellular adenosine triphosphate (ATP) levels decreased, together with reactive oxygen species (ROS) accumulation, membrane damage, and protein leakage. Together, these responses reduced the survival of S. aureus and E. coli and suppressed biofilm formation, while the coating retained cytocompatibility. Under mixed S. aureus / E. coli challenge, thermoelectrically activated Ag 2 Se-316L preserved mitochondrial homeostasis in bone marrow mesenchymal stem cells (BMSCs), accompanied by Nrf2/HO-1 upregulation and reduced DRP1 Ser616 phosphorylation; it also supported osteogenic and angiogenic responses. In a rat model of infected external fixation, Ag 2 Se-316L pins achieved an 82.3% antibacterial rate, attenuated peri-pin inflammation, increased peri-pin bone formation and maximum pull-out force, and produced a local tissue response characterized by enhanced pro-angiogenic and osteogenic protein expression and reduced osteoclastogenic signaling. This study presents a potentially translatable coating strategy that uses the transcutaneous thermal environment to alter interfacial electrostatics, perturb bacterial bioenergetics, and preserve a regenerative peri-pin microenvironment.