Feasibility study on Ti-15Mo-7Cu with low elastic modulus and high antibacterial property.

Titanium and titanium alloy with low density, high specific strength, good biological, excellent mechanical compatibility and easy to process have been widely used in the medical materials, but their application in orthopedics and dentistry often face bacterial infection, corrosion failure and stress shielding. In this paper, Ti-15Mo-7Cu (TM-7Cu) alloy was prepared by high vacuum non-consumable electric arc melting furnace and then treated by solution and aging treatment. The microstructure, mechanical properties, antibacterial properties and cytocompatibility were studied by X-ray diffraction, microhardness tester, electrochemical working station, antibacterial test and Live/Dead staining technology. The results have shown that the heat treatment significantly influenced the phase transformation, the precipitation of Ti2Cu phase, the elastic modulus and the antibacterial ability. With the extension of the aging time, the elastic modulus slightly increased and the antibacterial rate obviously increased. TM-7Cu alloy with a low elastic modulus of 83GPa and a high antibacterial rate of > 93% was obtained. TM-7Cu alloy showed no cytotoxicity to MC3T3. It was suggested that TM-7Cu might be a highly competitive medical material.

Development of a low elastic modulus and antibacterial Ti-13Nb-13Zr-5Cu titanium alloy by microstructure controlling.

In order to prepare a titanium with a low elastic modulus and good antibacterial property to meet the requirements as a biomedical material, Ti-13Nb-13Zr-5Cu (TNZ-5Cu) alloy was prepared by high vacuum consume electric arc melting furnace and then subjected to a solution treatment at 950 °C followed by a short-term aging treatment at 600 °C, for 15 min, 30 min, 1 h and 2 h, respectively. The microstructure, mechanical property, antibacterial property and biocompatibility of TNZ-5Cu were investigated in detail. The research results have shown that the solid solution treated alloy was mainly composed of ß-phase and α″-phase, while the aged alloys of ß-phase, α″-phase, α-phase and Ti2Cu. Compared with Ti-13Nb-13Zr alloy (65 GPa) and Ti-6Al-4 V alloy (111 GPa), the elastic modulus of TNZ-5Cu alloy after solution treatment was about 72 GPa and increased with the aging treatment up to 85 GPa, and the hardness was maintained at a higher level than that of Ti-13Nb-13Zr alloys (288 HV). The bacteria plate count results showed that the antibacterial ability of TNZ-5Cu alloy increased with the extension of the aging duration from <60% at 15-30 min to >90% at 1-2 h. Cell experiments showed that all TNZ-5Cu alloy had good cell compatibility. The low modulus and the antibacterial property could provide potential to avoid stress shield and device-related inflection in the clinical application.

What controls the antibacterial activity of Ti-Ag alloy, Ag ion or Ti2Ag particles?

Antibacterial metal materials, including Cu- and Ag-containing alloy, have attracted much attention worldwide. As for the antibacterial mechanism of the antibacterial alloys, there are two different views: metal ions sterilization and contact sterilization. For the purpose of revealing the key control factor, Titanium-silver (Ti-Ag) alloys with different silver contents were prepared and a surface acid etching was applied to change the silver ion release and the volume fraction of Ti2Ag on the surface. The microstructure, phase composition, elemental composition, surface roughness, hydrophilicity, silver ion release and antibacterial properties of Ti-Ag alloys were studied comprehensively by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle and roughness test, silver ion dissolution test and antibacterial test. The results have shown that the increasing of Ag content did not bring about any change to the surface roughness and hydrophilicity but enhanced the Ag ion release while the surface acid etching improved the hydrophilicity, enhanced the Ag ion release and made more Ti2Ag particles appear on the surface. The antibacterial experiments have shown that the antibacterial properties increased with the increasing of Ag content in Ti-Ag alloys and that the surface acid etching improved the antibacterial activity significantly. The calculated results and surface microstructure observation and XPS analysis demonstrated that the antibacterial activity of Ti-Ag alloys was mainly controlled by Ti2Ag particle in a contact sterilization mode. Silver ion release from Ti-Ag alloy also contributed to antibacterial activity of Ti-Ag, but the Ag ion sterilization was not the key antibacterial mechanism. Finally, the CCK-8 results showed that all Ti-Ag alloys exhibited good cell compatibility.