In vitro biological response to the oxide layer in pure titanium formed at different current densities by plasma electrolytic oxidation

Graphical abstract: - Highlights: • Crater-like pores, ∼2 μm in size, were found on the oxide layer formed at 100 mA/cm². • Current density of 100 mA/cm² allowed to form well-developed oxide nodules on a surface. • High surface roughness and volume fraction of anatase triggered the formation of apatite. • Attachment and viability of osteoblast cells were improved under 100 mA/cm² condition. - Abstract: This study examined the influence of the current density on the surface characteristics and biological response of titanium oxide layers produced by a plasma electrolytic oxidation process. For this purpose, the present processes were carried out under alternating current conditions in a phosphate electrolyte for 300 s at current densities of 100, 150, 200, and 250 mA/cm². The pore size decreased with decreasing the current density, whereas the mean surface roughness and amount of anatase phase increased. This tendency is considered suitable for the formation of biomimetic apatite and the proliferation of osteoblast cells. The in vitro examinations showed that the formation of biomimetic apatite and the proliferation of osteoblasts on the titanium oxide layer produced at 100 mA/cm² were highest among the samples evaluated