Ultraviolet photofunctionalization of nanostructured titanium surfaces enhances thrombogenicity and platelet response

The purpose of this study was to evaluate blood and platelet response to nanostructured TiO₂ coatings and to investigate the effect of Ultraviolet (UV) light treatment on blood clotting ability, platelet activation and protein adhesion. Ti-6Al-4V titanium alloy plates (n = 138) were divided into three groups; a sol-gel derived MetAlive^TM coating (MA); hydrothermal coating (HT); and a non-coated group (NC). Sixty nine titanium substrates were further treated with UV light for 1 h. The thrombogenicity of the titanium substrates was assessed using fresh human blood with a whole blood kinetic clotting time method. The platelet adhesion test was conducted to evaluate the morphology and adhesion behavior of the platelets on the titanium substrates. Human diluted plasma and bovine fibronectin were used to evaluate protein adsorption. Total clotting time for the UV treated HT, MA and NC titanium substrates was almost 40 min compared to 60 min for non-UV substrates, the total clotting time for the UV treated groups were significantly lower than that of the non UV NC group (p < 0.05). UV light treatment had significantly enhanced coagulation rates. The HT and MA substrates presented more platelet aggregation, spreading and pseudopod formation in comparison with the NC substrates. UV treatment did not affect the platelet activation and protein adsorption. This in vitro study concluded that nanostructured titanium dioxide implant surfaces obtained by sol-gel and hydrothermal coating methods increased coagulation rates and enhanced platelet response when compared with non-coated surfaces. UV light treatment clearly improved thrombogenicity of all examined Ti-6Al-4V surfaces.