Biocompatibility of Nanoscale Hydroxyapatite Coating on TiO2 Nanotubes

In this study, a highly-ordered TiO2 nanotube array was successfully fabricated on the surface of a pure titanium foil using the anodization method, and a hydroxyapatite (HA) layer was electrochemically deposited on the vertically aligned titania (TiO2) nanotube array. The TiO2 nanotubes exhibited an inner diameter ranging from 44.5 to 136.8 nm, a wall thickness of 9.8 to 20 nm and a length of 1.25 to 3.94 µm, depending on the applied potential, and the anodization time and temperature. The TiO2 nanotubes provided a high number of nucleation sites for the HA precipitation during electrochemical deposition, resulting in the formation of a nanoscale HA layer with a particle size of about 50 nm. The bond strength between the HA coating and the nanotubular layer with an inner diameter of 136.8 nm was over 28.7 MPa, and the interlocking between the nanoscale HA and the TiO2 nanotubes may have been responsible for the high bond strength. The biocompatibility assessment was conducted on Ti foil with a composite coat of nanoscale HA and the TiO2 nanotube array by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) array with mesenchymal stem cells (MSCs). The mesenchymal stem cells adhered to and spread onto the nanoscale HA layer with plenty of extending filopodia, indicating excellent biocompatibility of the HA coat, the composite coat of nanoscale HA and the TiO2 nanotube array. The findings suggest that the nanoscale HA coating on the TiO2 nanotube array might be a promising way to improve the bond strength and the compatibility of the HA layer.</jats:p

Effect of Rolling Treatment on Microstructure, Mechanical Properties, and Corrosion Properties of WE43 Alloy

Magnesium alloys show broad application prospects as biodegradable implanting materials due to their good biocompatibility, mechanical compatibility, and degradability. However, the influence mechanism of microstructure evolution during forming on the mechanical properties and corrosion resistance of the magnesium alloy process is not clear. Here, the effects of rolling deformation, such as cold rolling, warm rolling, and hot rolling, on the microstructure, mechanical properties, and corrosion resistance of the WE43 magnesium alloy were systematically studied. After rolling treatment, the grains of the alloy were significantly refined. Moreover, the crystal plane texture strength and basal plane density decreased first and then increased with the increase in rolling temperature. Compared with the as-cast alloy, the strength of the alloy after rolling was significantly improved. Among them, the warm-rolled alloy exhibited the best mechanical properties, with a tensile strength of 346.7 MPa and an elongation of 8.9%. The electrochemical experiments and immersion test showed that the hot working process can greatly improve the corrosion resistance of the WE43 alloy. The hot-rolled alloy had the best corrosion resistance, and its corrosion resistance rate was 0.1556 ± 0.18 mm/year

Effect of Rolling Treatment on Microstructure, Mechanical Properties, and Corrosion Properties of WE43 Alloy

Magnesium alloys show broad application prospects as biodegradable implanting materials due to their good biocompatibility, mechanical compatibility, and degradability. However, the influence mechanism of microstructure evolution during forming on the mechanical properties and corrosion resistance of the magnesium alloy process is not clear. Here, the effects of rolling deformation, such as cold rolling, warm rolling, and hot rolling, on the microstructure, mechanical properties, and corrosion resistance of the WE43 magnesium alloy were systematically studied. After rolling treatment, the grains of the alloy were significantly refined. Moreover, the crystal plane texture strength and basal plane density decreased first and then increased with the increase in rolling temperature. Compared with the as-cast alloy, the strength of the alloy after rolling was significantly improved. Among them, the warm-rolled alloy exhibited the best mechanical properties, with a tensile strength of 346.7 MPa and an elongation of 8.9%. The electrochemical experiments and immersion test showed that the hot working process can greatly improve the corrosion resistance of the WE43 alloy. The hot-rolled alloy had the best corrosion resistance, and its corrosion resistance rate was 0.1556 ± 0.18 mm/year.</jats:p