Cellular Compatibility And Tribological Properties Of Surface-Nanostructural Titanium

In this work, we prepared a series of nano-tube/hole layers on Ti with six different inner diameters of-50nm,-100nm,170nm,250nm, and 400nm by anodic oxidation and microarc oxidation. Morphologies, the phase components, roughness, hydrophilicity, microhardness, and nanohardness of the specimen surfaces were analyzed by a scanning electron microscope, X-ray diffractometer, surface roughometer, goniometer, and hardness instrument. Cellular compatibility and tribological properties of surface-nanostructural Ti were evaluated.Preliminarily, MC3T3-E1 mouse osteoblastic cells were cultured on the specimen surfaces to study cellular compatibility of the TiO2 nano-tubes/holes and investigate the influence of the tube/hole inner diameters on osteoblastic adhesion, proliferation and differentiation. For anodized specimens whose nanotube diameters are less than 170nm, activity, proliferation, and differentiation abilities of the osteoblastic cells decreased as tube inner diameter increased. However, for specimens with nano-tube/hole diameters of-170nm,-250nm, and-400nm, these abilities of the cells increased as the diameters of nanoholes increased. Compared with amorphous-structural TiO2 nanotubes, the anatase-structural nanotubes showed better cellular compatibility.In order to further study the effects of the inner diameter sizes on cell behaviors, we chose the osteoblastic cells from Sprague Dawley rat and prepared nano-tubes/holes with three diameter sizes,-50nm,-170nm, and-400nm. We focused on the early responses such as cell adhesion, morphology, actin cytoskeleton, and proliferation of the cells on specimens and investigated subsequent cellular development of the osteoblastic differentiation, and mineralization. The results indicated that inner diameter of nano-tube/hole affected the various behaviors of osteoblasts. The specimen with nanotube diameter of-170nm after heat treatment (170nm-A-HT) has the best cellular compatibility. The cells on 170nm-A-HT had the best abilities of proliferation, differentiation, and ossification.The friction properties of it TiO2 nanotube layers has an important influence on its reliability and functionality in clinics. Fretting wear is one of the main wear forms of hard tissue implants. The fretting wear tests of anodized flat specimens, with nanohole inner diameters of-50nm,-100nm, and-170nm, were carried out against GCr15 steel ball and under the 40N tangential load in dry friction and lubrication conditions respectively. The wear mechanism of the nanotube layers involved abrasive wear, fatigue wear, adhesive wear and oxidative wear. Both in dry and lubrication conditions, the specimen with nanotube diameter of-170nm had the lowest friction coefficient. Under lubrication, wear depth of 170nm-A-HT was the least. Wear depth of specimens were mainly related with change of hardness fore-and-aft heat treatment and nanotube diameters of specimen surfaces.Ultrahigh molecular weigh tpolyethylene (UHMWPE) was usually used in artificial acetabulum. The fretting wear tests of the anodized specimens against UHMWPE ball were carried out under four kinds of normal load (40N,60N,80N, 100N) respectively in air atmosphere and lubrication conditions. Results suggested that in wear against UHMWPE, TiO2 nanotube layers had good properties of bearing, anti-stripping and wear-resistance. The wear mechanism of the friction pair involved abrasive wear and material loss on surface layer resulted from UHMWPE plastic deformation. Coefficients of friction decreased as normal load increased for the same friction pair. Frictional coefficients were mainly related with nanotube diameters of specimens, next with surface roughness and elastic modulus of specimens. The heat treated-50nm specimen showed the lowest frictional coefficient and wear degree of the. Under dry friction condition, nano-tubes/holes obviously reduced the wear of pure Ti and UHMWPE.