RF magnetron sputtering mediated NiTi/Ag coating on Ti-alloy substrate with enhanced biocompatibility and durability

Abstract

Mechanically robust, biocompatible and corrosion resistant Ag doped NiTi (NiTi/Ag) coatings were formed on implant grade commercially pure titanium substrates by R.F. magnetron sputtering. Five samples with varying silver content (0, 1, 3, 7, and 10 at.%) were prepared by controlling the power applied to Ag and NiTi targets. The intensity of X-ray photoelectron spectra peaks corresponding to Ni2p, Ti2p, Ag3d components were found proportional to respective coating compositions. The soft Ag crystallites were decreased the roughness and crystallinity of NiTi/Ag. Among all compositions, NiTi/Ag coating with 3 at.% Ag exhibited lowest friction coefficient (0.1) and wear rate (0.69 x 10(-07) mm(3)/N * mm). Electrochemical corrosion measurements indicated that Ag incorporation increased the corrosion resistance of NiTi. Increase in Ag content shifted E-corr values in the anodic direction, and reduced the current density by one-order-of-magnitude. When cultured on NiTi/Ag coating with 3 at.% Ag, human dermal fibroblast neonatal cells demonstrated highest cell viability. The fluorescence micrographic image of the immununostained cells showed a well grown actin filament network. Overall, NiTi/Ag coated titanium substrates were found to be a promising orthopedic implant material.