Properties of Titanium Oxide Coating on MgZn Alloy by Magnetron Sputtering for Stent Application

Abstract

Constructing surface coatings is an effective way to improve the corrosion resistance and biocompatibility of magnesium alloy bioabsorbable implants. In this present work, a titanium oxide coating with a thickness of about 400 nm was successfully prepared on a MgZn alloy surface via a facile magnetron sputtering route. The surface features were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the contact angle method. The corrosion behavior and biocompatibility were evaluated. The results indicated that the amorphous TiO2 coating with a flat and dense morphology was obtained by magnetron-sputtering a titanium oxide target. The corrosion current density decreased from 1050 (bare MgZn alloy) to 49 μA/cm2 (sample with TiO2 coating), suggesting a significant increase in corrosion resistance. In addition, the TiO2 coating showed good biocompatibilities, including significant reduced hemolysis and platelet adhesion, and increased endothelial cell viability and adhesion.

Advances in coatings on magnesium alloys for cardiovascular stents – A review

“…Yang et al [ 86 ] reported the deposition of a TiO 2 film on Mg-Zn alloys via the ALD method (an advanced technology that adopts surface sequential reactions to achieve atomic-level film deposition and has the merits of improving the surface coverage and adhesion of the thin film [ 90 ]), the TiO 2 -150 °C nanoscale film protected Mg alloy from corrosion and promoted endothelial cells (ECs) adhesion and proliferation; however, the TiO 2 -200 °C thin film showed an unsatisfactory result in cell assays because of its unstable surface microstructure and lower than optimal surface energy, which did not match that of key proteins for mediating ECs attachment. Hou et al [ 91 ] successfully prepared a 400 nm-thick TiO 2 coating on Mg-Zn Alloy via a facile magnetron sputtering (MS) route at room temperature and evaluated the biocompatibility and corrosion resistance of the resulting material. The outcomes showed that the degradation behavior of Mg alloys was suppressed apparently, and the degradation degree of Mg alloys coated with TiO 2 was not serious after 14 d of soaking in simulated body fluid (SBF) solution.…”

“… Mg–Zn TiO 2 0.05 SBF – – 789.5 24.4 18.04 0.557 – Ameliorative corrosion resistance was offered by the TiO 2 coating, and drugs were expected to be loaded on the TiO 2 film by physical adsorption [ 89 ]. Mg–Zn TiO 2 0.400 SBF −1.70 −1.65 1050 49.0 23.99 1.119 14 TiO 2 film had a low HR (1%) and inhibited platelet adhesion and promoted ECs attachment [ 91 ]. AZ31B Mg(OH) 2 – SBF −1.57 −1.174 37.26 2.052 0.851 0.046 7 MgF 2 coating had relatively better corrosion resistance than Mg(OH) 2 coating, however, Mg(OH) 2 coating showed better anti-thrombosis and cytocompatibility to ECs than MgF 2 coating [ 109 ].…”

A Comprehensive Review on Surface Modifications of Biodegradable Magnesium-Based Implant Alloy: Polymer Coatings Opportunities and Challenges

“…As a result, the future focus may be on enhancing the barrier effect and binding force for a full-life corrosion-resistant service. In this regard, composite coating may be a viable option for increasing the adhesion force of organic biopolymer coating [117][118][119][120][121][122][123][124][125][126][127][128][129][130][131][132][133][134]. Furthermore, the formation of composite coatings not only improves corrosion resistance but also endows the Mg alloys with potential bioactivity and biocompatibility in long-term tests.…”

Recent Progress in Surface Modification of Mg Alloys for Biodegradable Orthopedic Applications

“…However, samples annealed postdeposition showed cracks causing rapid degradation and poor cell adhesion. Hou et al (2020) reported excellent anti-hemolytic property and cytocompatibility for TiO 2 sputter coating. The hemolysis ratio of MgZn alloy was significantly reduced from 47 to 0.1% after TiO 2 sputter coating.…”