Effect of surface modification by nitrogen ion implantation on the electrochemical and cellular behaviors of super-elastic NiTi shape memory alloy

Abstract

The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release.

Biocompatibility and Inflammatory Potential of Titanium Alloys Cultivated with Human Osteoblasts, Fibroblasts and Macrophages

“…In the end, the cellular response to materials depends on the specific cell types, materials processing, and testing conditions [10,32,60]. Furthermore, surface roughness, topography, and chemistry are crucial factors for cell adhesion, proliferation, and differentiation [3,8,14,61,62,63,64,65]. In our present in vitro study, the Ti6Al4V and NiTi alloys also differed strongly in roughness values.…”

Effect of hydroxyapatite‐titanium‐MWCNTs composite coating fabricated by electrophoretic deposition on corrosion and cellular behavior of NiTi alloy

“…R ct corresponds to the electric double layer at the metal‐coating interface, the nature of which is derived from the interaction of the corrosive ions and the metal substrate . By increasing the R ct , fewer ions can transfer through the electric double layer (at the substrat‐coating interface) . By applying the coating on the surface of the NiTi alloy, due to the increasing of the resistance coefficient of the coating, and increasing the resistance of the double layer resulted from the bonding on the surface of the metal (the bond between the atoms of the coating and the NiTi substrate), the corrosion resistance of the NiTi alloy improved .…”

“…The coated NiTi specimens (especially the NiTi coated with HA‐Ti‐MWCNTs) revealed a very high safety (regarding nickel ions release) in the body. The degree of biocompatibility of an implant is determined using the biological responses that occur at the surface of the implant in the body . The release of toxic ions from the implant into the body due to the corrosion reactions occur on its surface, will result in cytotoxicity as the toxic ions react with the surrounding tissue cells .…”

“…The degree of biocompatibility of an implant is determined using the biological responses that occur at the surface of the implant in the body . The release of toxic ions from the implant into the body due to the corrosion reactions occur on its surface, will result in cytotoxicity as the toxic ions react with the surrounding tissue cells . Laing et al examined the biochemical effects of the nickel plate on the body tissue and observed the cytotoxicity and necrosis of the muscle and bone tissue around the nickel plate.…”

“…As a result, cell proliferation increased in the cell culture medium containing coated NiTi specimens. Investigating the biological behavior of the NiTi alloy in the cell culture medium revealed that the released toxic Ni ions from the surface of the NiTi alloy disrupted the proliferation of the fibroblast cells in the culture medium . By decreasing the corrosion rate and intensifying the release of the toxic ions from the implant surface, the biocompatibility of the implant will improve.…”