Biocompatibility evaluation of novel β-type titanium alloy (Ti–35Nb–7Zr–5Ta)98Si2in vitro

Abstract

Background: low elastic modulus and high strength are two critical requirements for orthopedic implant materials. A newly reported ultrafine-grained β-type titanium alloy (Ti–35Nb–7Zr–5Ta)₉₈Si₂, which was designed by d-electron alloy design theory and fabricated by spark plasma sintering, exhibits both low elastic modulus and high strength. However, its biocompatibility remains largely unclear. Methods: the microstructure of the (Ti–35Nb–7Zr–5Ta)₉₈Si₂ alloy was examined by scanning electron microscopy. Its effects on fibroblast cell proliferation and osteoblast cell adhesion, morphology, differentiation, inflammatory response, apoptosis, and biomineralization were investigated in in vitro studies. The commercial Ti₆Al₄V alloy was studied side-by-side for comparison. Results: the (Ti–35Nb–7Zr–5Ta)₉₈Si₂ alloy displayed a two-phase microstructure, in which isolated semi-round equiaxed intermetallic hexagonal (Ti, Zr)₂Si(S2) grains were dispersed within a continuous body-centered cubic (bcc) β-Ti matrix. Both phases were composed of ultrafine grains of several hundred nm. Similar to the Ti₆Al₄V alloy, the (Ti–35Nb–7Zr–5Ta)₉₈Si₂ alloy exhibited low cytotoxicity towards L-929 fibroblasts and allowed effective MC3T3-E1 osteoblast attachment with no significant effects on cell differentiation, inflammatory response, apoptosis or biomineralization. Conclusion: this study demonstrates that the newly reported β-type titanium alloy (Ti–35Nb–7Zr–5Ta)₉₈Si₂, which has been reported to exhibit improved mechanical properties displays excellent biocompatibility. Therefore, this alloy may be a superior implant material in biomedical implantation.