A superparamagnetic Fe3O4–TiO2 composite coating on titanium by micro-arc oxidation for percutaneous implants

Abstract

A micro-magnetic field can affect the cell response and the subsequent tissue integration of implants. To improve the weak skin integration of percutaneous Ti implants, herein, superparamagnetic TiO₂ coatings with Fe₃O₄ nanoparticles (NPs) were fabricated by micro-arc oxidization, and the magnetic field gradient induced by Fe₃O₄ was expected to enhance the fibroblast response in vitro and bio-sealing in vivo. Moreover, the surface properties of TiO₂ coatings with Fe₃O₄ in different amounts were investigated, and the fibroblast and Staphylococcus aureus response in vitro as well as skin integration in vivo were evaluated. The obtained results showed that with an increase in the amount of Fe₃O₄ NPs in the electrolyte, more Fe₃O₄ were incorporated into the TiO₂ coatings, and the Fe content could reach 4.41 wt%. The incorporation of Fe₃O₄ endowed TiO₂ with superparamagnetism without changing its surface properties including the phase composition, Ca²⁺ release, roughness and hydrophilicity. The Fe₃O₄ NPs with the size of about 10 nm were mainly distributed in the near-surface region of TiO₂. With an increase in the amount of Fe₃O₄ in TiO₂, the magnetic property of TiO₂ increased, and the fibroblast response, including proliferation, phenotype and extracellular collagen secretion, were improved. Compared to pure TiO₂, TiO₂ with 4.41 wt% Fe reduced bacterial reproduction to about 60% and efficiently prevented the recession and inflammatory reaction of soft tissue, showing good integration with skin tissues. Thus, herein, we provide a potential coating that can be applied on percutaneous Ti implants.