Photoelectrons Sequentially Regulate Antibacterial Activity and Osseointegration of Titanium Implants.

Titanium implants are widely used in the biological field, however, implantation occasionally fails due to infection from the microbes during the surgery or poor osseointegration after the surgery. To solve the problem, we have designed an intelligent functional surface on the titanium implant that can sequentially eradicate bacteria biofilm at the initial period of post-surgery time and promote osseointegration at the late period of post-surgery time. Such surface can be excited by near infrared light (NIR), with rare earth nanoparticles (RE NPs) to upconvert the NIR light to visible range and adsorbed by Au nanoparticles (Au NPs), supported by TiO 2 porous film grown tightly on titanium implants. Under NIR irradiation, the implant converts the energy of phonon to hot electrons and lattice vibrations at the surface, where the former flows directly to the contact substance or partially reacts with the surrounding to generate reactive oxygen species, and the latter leads to the increase of local temperature. The in vitro and in vivo experiments have suggested that the biofilm or microbes on the implant surface could be eradicated by NIR treatment. In addition, the surface exhibits superior biocompatibility for cell survival, adhesion, proliferation, and osteogenic differentiation, which provides the foundation for osseointegration. In-vivo implantation experiments (micro-computed tomography (micro-CT), histological analysis, etc.) demonstrate that osseointegration is promoted, which could be attributed to the photoelectron-induced manipulation of the osteogenesis-related cells, surface topography, and bioactivity of functional nanoparticles. Our work thus has demonstrated that NIR-generated electrons by upconversion can sequentially eradicate biofilms and regulate the osteogenic process, which provides a new direction to fabricate an efficient implant surface. This article is protected by copyright. All rights reserved.