A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys

Abstract

Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy.

Surface modification of Ni–Ti alloys for stent application after magnetoelectropolishing

“…All tests were conducted at a scan rate of 1.0 mV/s utilizing an exposed working electrode area of 1.0 cm 2 . The electrolyte was purged with high purity nitrogen for 30 min prior to immersion of the working electrode, as well as continuously during the corrosion test [26]. …”

Effect of anodization and annealing on corrosion and biocompatibility of NiTi alloy

“…The surface showed negative hysteresis loop and therefore it can be assumed that the oxide film formed after annealing is compact and could effectively protect the bulk NiTi alloy. The difference between breakdown potential, E b and rest potential, E r gives the susceptibility of the surface for pitting corrosion [33]. Both bare NiTi and as-anodized NiTi are prone to pitting corrosion while annealed surface is resistant to pitting corrosion.…”

Electrochemical characterization and in-vitro bio-assessment of AZ31B and AZ91E alloys as biodegradable implant materials

“…Mostly the metal surfaces are electropositive due to the presence of oxides and sulfides molecules, which attracts (-OH) group of water molecules, due to polar molecular behavior but the magnitude is depend on the surface treatments and the surface composition. That's why the surface modification take advantage of the surface free energy and helps in altering the surface easily [33]. However, the application of the wettability in implantable materials is still under research.…”