Building biointegration of Fe2O3-FeOOH coated titanium implant by regulating NIR irradiation in an infected model

Killing bacteria, eliminating biofilm and building soft tissue integration are very important for percutaneous implants which service in a complicated environment. In order to endow Ti implants with above abilities, multifunctional coatings consisted of Fe2O3-FeOOH nanograins as an outer layer and Zn doped microporous TiO2 as an inner layer were fabricated by micro-arc oxidation, hydrothermal treatment and annealing treatment. The microstructures, physicochemical properties and photothermal response of the coatings were observed; their antibacterial efficiencies and cell response in vitro as well as biofilm elimination and soft tissue integration in vivo were evaluated. The results show that with the increased annealing temperature, coating morphologies didn't change obviously, but lattices of beta-FeOOH gradually disorganized into amorphous state and rearranged to form Fe2O3. The coating annealed at 450 degrees C (MA450) had nanocrystallized Fe2O3 and beta-FeOOH. With a proper NIR irradiation strategy, MA450 killed adhered bacteria efficiently and increased fibroblast behaviors via upregulating fibrogenic-related genes in vitro; in an infected model, MA450 eliminated biofilm, reduced inflammatory response and improved biointegration with soft tissue. The good performance of MA450 was due to a synergic effect of photothermal response and released ions (Zn2+ and Fe3+).

Automated summary

A dual-layer coating, consisting of Fe2O3-FeOOH nanograins as the outer layer and Zn-doped microporous TiO2 as the inner layer, was fabricated using micro-arc oxidation, hydrothermal treatment, and annealing treatment. The coating showed excellent performance in killing bacteria, eliminating biofilm, and promoting soft tissue integration, which was attributed to the synergistic effect of photothermal response and released ions.