Abstract
Tantalum (Ta) metal is receiving increasing interest as biomaterial for load-bearing orthopedic applications and the synthetic properties of Ta can be tailored by altering its grain structures. This study evaluates the capability of sliding friction treatment (SFT) technique to modulate the comprehensive performances of pure Ta. Specifically, novel nanocrystalline (NC) surface with extremely small grains (average grain size of ≤20 nm) was fabricated on conventional coarse-grained (CG) Ta by SFT. It shows that NC surface possessed higher surface hydrophilicity and enhanced corrosion resistance than CG surface. Additionally, the NC surface adsorbed a notably higher percentage of protein as compared to CG surface. The in vitro results indicated that in the initial culture stages (up to 24 h), the NC surface exhibited considerably enhanced osteoblast adherence and spreading, consistent with demonstrated superior hydrophilicity on NC surface. Furthermore, within the 14 days culture period, NC Ta surface exhibited a remarkable enhancement in osteoblast cell proliferation, maturation and mineralization as compared to CG surface. Ultimately, the improved osteoblast functions together with the good mechanical and anti-corrosion properties render the SFT-processed Ta a promising alternative for the load-bearing bone implant applications.
Highlights
Tantalum (Ta) metal is receiving increasing interest as biomaterial for load-bearing orthopedic applications due to its excellent biocompatibility (e.g., outstanding bone-like apatite forming capability in simulated body fluid (SBF), no cytotoxic ion release or dissolution in local, systemic and remote organs, as well as good osseointegration), superior strength, as well as anti-corrosion properties[1,2,3,4,5]
Our present study demonstrated that the NC Ta surface possessed superior anti-corrosion property as compared to the CG Ta sample (Fig. 3, Table 1), this helps to create a more stable microenvironment that benefits the cellular functions at the cell-substrate interface as well[36]
Our results demonstrated higher mRNA level and activity of alkaline phosphatase (ALP) on the NC Ta surface compared to the CG Ta surface at 3 and 7 days (Figs 6d and 7a), indicating that the osteoblast cultured on the NC Ta surface differentiated to a more mature phenotype
Summary
Tantalum (Ta) metal is receiving increasing interest as biomaterial for load-bearing orthopedic applications due to its excellent biocompatibility (e.g., outstanding bone-like apatite forming capability in simulated body fluid (SBF), no cytotoxic ion release or dissolution in local, systemic and remote organs, as well as good osseointegration), superior strength, as well as anti-corrosion properties[1,2,3,4,5]. In vitro studies[3,6] comparing the Ta implant and the common titanium (Ti) implant show that the bioactivity and cell-material interactions are significantly better in the case of Ta, further indicating Ta exhibits high promise for bone implant application. With regard to Ta, due to the high plastic deformation resistance of typical body-centered cubic (BCC) metal, nanocrystalline (NC) Ta is generally hard to obtain and the biological performance of NC Ta has scarcely been explored to our knowledge. Surface mechanical grinding treatment (SMGT)[15,16] or sliding friction treatment (SFT)[17,18,19] with quite high strain rate of about 103–104 s−1 is a favorable severe plastic deformation (SPD) method that can generate a solid layer of nanocrystalline structure on the metal surface. Grain structures of the (a) CG Ta and (b) NC Ta samples
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