Enhanced antibacterial activity, corrosion resistance and endothelialization potential of Ti-5Cu alloy by oxygen and nitrogen plasma-based surface modification

Abstract

Antibacterial Ti-5Cu alloy is a promising substitute material for Ti-made cardiovascular implants, so its surface engineering is crucial to expediting clinical implementation. Given the antibacterial and cardiovascular biological benefits of Cu2+ and titanium-nitride-oxide (TiNxOy) coatings, a Cu2O/CuO-TiNxOy coating with upregulated Cu2+ release was successfully deposited on Ti-5Cu alloy for the first time using oxygen and nitrogen plasma-based surface modification. The superhydrophilic and nanostructured Cu2O/CuO-TiNxOy coating had a dense structure and was well bonded to the substrate, resulting in enhanced corrosion resistance, while CuO/Cu2O in the coating released Cu2+ faster than Ti2Cu phase in the matrix. More gratifying, the coating demonstrated perfect antibacterial properties (R > 99.9% against S. aureus), owing primarily to direct contact sterilization of Cu2O/CuO. The most encouraging phenomenon was that the coating dramatically accelerated HUVEC adhesion (1.4 times), proliferation (RGR: 106%–116%), and particularly migration (RMR: 158%–247%) compared with the control Ti. The coating extract also significantly stimulated in vitro angiogenesis capacity. The rapid endothelialization for Cu2O/CuO-TiNxOy coating was attributed to the surface nanostructure and Cu2+/NO2− release, which upregulated the angiogenesis-related gene expression of HIF-1α, VEGF, and eNOS to increase VEGF secretion and NO production. All of the findings indicated that the Cu2O/CuO-TiNxOy coating could enhance the corrosion resistance, antibacterial properties, and endothelialization potential of Ti-Cu alloy, displaying great clinical potential in cardiovascular applications.