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

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.