Significant improvement in cell adhesion and wear resistance of biomedical β-type titanium alloy through ultrasonic nanocrystal surface modification

Abstract

A novel β-type Ti–29Nb–13Ta–4.6Zr (TNTZ) alloy with a low Young's modulus, high bio-corrosion resistance, and excellent biocompatibility has been recently introduced for implant applications. Here, ultrasonic nanocrystal surface modification (UNSM) treatment was applied to TNTZ alloy to improve its wear resistance and biofunctionality. Application of UNSM to a TNTZ alloy resulted in the generation of a nanostructured surface layer. The wear resistance of the UNSM-treated specimen was observed to be more than 7 times higher than that of the untreated one. Cell culture tests indicated that MC3T3 cells adhered and spread more readily on the UNSM-treated specimen than on the untreated one. MTT assays after 1 and 4 days in culture also indicated enhancement of cell proliferation on the UNSM-treated specimen than that of the untreated one. Live/dead assay revealed no significant cytotoxicity in either substrate. The significant improvement of cell adhesion, spreading, and proliferation on the UNSM-treated TNTZ alloy specimen were attributed to both grain refinement and micro-patterned surface effects. These results demonstrate that UNSM-treatment not only improves the wear resistance of TNTZ alloy, but also enhances its biocompatibility, which makes it a strong candidate for applications in medical implants.