Biosafety, stability, and osteogenic activity of novel implants made of Zr₇₀Ni₁₆Cu₆Al₈ bulk metallic glass for biomedical application.

Abstract

Superior mechanical and chemical properties of Zr₇₀Ni₁₆Cu₆Al₈ bulk metallic glass (BMG) demonstrate its promise as a novel biomaterial for fabrication of implants. The aim of the present study was to validate mechanical, chemical, and biological properties of Zr₇₀Ni₁₆Cu₆Al₈ BMG through comparison with titanium (Ti). Our data indicated higher tensile strength, lower Young's modulus, and reduced metal ion release of Zr₇₀Ni₁₆Cu₆Al₈ BMG compared with Ti. Biosafety of bone marrow mesenchymal cells on Zr₇₀Ni₁₆Cu₆Al₈ BMG was comparable to that of Ti. Next, screw-type implant prototypes made of Zr₇₀Ni₁₆Cu₆Al₈ BMG were fabricated and inserted into rat long bones. Zr₇₀Ni₁₆Cu₆Al₈ BMG implants indicated a higher removal-torque value and lower Periotest value compared with Ti implants. In addition, higher amounts of new bone formation and osseointegration were observed around Zr₇₀Ni₁₆Cu₆Al₈ BMG implants compared with Ti implants. Moreover, gene expression analysis displayed higher expression of osteoblast- and osteoclast-associated genes in the Zr₇₀Ni₁₆Cu₆Al₈ BMG group compared with the Ti group. Importantly, loading to implants upregulated bone formation, as well as osteoblast- and osteoclast-associated gene expression in the peri-implant area. No significant difference in concentrations of Ni, Al, Cu, and Zr in various organs was shown between in the Zr₇₀Ni₁₆Cu₆Al₈ BMG and Ti groups. Collectively, these findings suggest that Zr₇₀Ni₁₆Cu₆Al₈ BMG is suitable for fabricating novel implants with superior mechanical properties, biocompatibility, stability, and biosafety compared with Ti. Titanium is widely used to fabricate orthopedic and dental implants. However, Titanium has disadvantages for biomedical applications in regard to strength, elasticity, and biosafety. Recently, we developed a novel hypoeutectic Zr₇₀Ni₁₆Cu₆Al₈ BMG, which has superior mechanical and chemical properties. However, the validity of Zr₇₀Ni₁₆Cu₆Al₈ BMG for biomedical application has not been cleared. The aim of the present study was to validate the mechanical, chemical, and biological properties of Zr₇₀Ni₁₆Cu₆Al₈ BMG for biomedical applications through comparison with Titanium. The present study clarifies that Zr₇₀Ni₁₆Cu₆Al₈ BMG has good mechanical properties, corrosion resistance, and osteogenic activity, which are necessary features for biomedical applications. The present study provides for the first time the superiority of Zr₇₀Ni₁₆Cu₆Al₈ BMG implants to Titanium implants for biomedical applications.