In vitro bioactivity study of TiCaPCO(N) and Ag-doped TiCaPCO(N) films in simulated body fluid.

Bioactivity of multicomponent TiCaPCO(N) and Ag-doped TiCaPCO(N) films was evaluated in vitro using simulated body fluid (SBF) and compared with that of bioactive glass Biogran. The first group of films was fabricated by magnetron sputtering of composite TiС0.5 -Ti3 POx -CaO target produced via the self-propagating high-temperature synthesis (SHS) method (TiCaPCON films), after which their surface was implanted with Ag+ ions to obtain Ag-doped TiCaPCON films. The second group of films was fabricated by pulsed electrospark deposition (PED) using SHS-produced composite TiС0.5 -Ti3 POx -CaO and TiС0.5 -Ti3 POx -CaO-Ag electrodes. After immersion in SBF, the structure and chemistry of surface were well characterized using a combination of various microanalytical techniques, such as scanning electron microscopy, X-ray diffractometry (both in conventional and grazing incidence mode), Fourier transform infrared spectroscopy, Raman spectroscopy, and glow discharge optical emission spectroscopy. The results showed that the surfaces of the TiCaPCO(N) and Ag-doped TiCaPCO(N) films were bioactive in vitro and induced the formation of an apatite layer during exposure in SBF. In the case of the magnetron-sputtered films, the apatite layer was formed over 14 days, while 28 days were needed to form CaP phase on the surface of PED-modified samples. Various factors (film structure, surface roughness, surface functional groups, surface charge, and composition, supersaturation, and near-surface local supersaturation of SBF) affecting the kinetics of bone-like apatite formation on a bioactive surface are discussed.