L.H. Yin

In vitro biocompatibility of titanium-nickel alloy with titanium oxide film by H2O2 oxidation

Titanium oxide film with a graded interface to NiTi matrix was synthesized in situ on NiTi shape memory alloy(SMA) by oxidation in H2O2 solution. In vitro studies including contact angle measurement, hemolysis, MTT cytotoxicity and cell morphology tests were employed to investigate the biocompatibility of the H2O2-oxidized NiTi SMAs with this titanium oxide film. The results reveal that wettability, blood compatibility and fibroblasts compatibility of NiTi SMA are improved by the coating of titanium oxide film through H2O2 oxidation treatment.

Surface treatment of NiTi shape memory alloy by modified advanced oxidation process

A modified advanced oxidation process(AOP) utilizing a UV/electrochemically-generated peroxide system was used to fabricate titania films on chemically polished NiTi shape memory alloy(SMA). The microstructure and biomedical properties of the film were characterized by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), inductively-coupled plasma mass spectrometry(ICPMS), hemolysis analysis, and blood platelet adhesion test. It is found that the modified AOP has a high processing effectiveness and can result in the formation of a dense titania film with a Ni-free zone near its top surface. In comparison, Ni can still be detected on the outer NiTi surface by the conventional AOP using the UV/H2O2 system. The depth profiles of O, Ni, Ti show that the film possesses a smooth graded interface structure next to the NiTi substrate and this structure enhances the mechanical stability of titania film. The titania film can dramatically reduce toxic Ni ion release and also improve the

Cytocompatibility and haemocompatibility of Zr, ZrC and ZrCN films

Abstract The cytocompatibility and haemocompatibility of three zirconium based films, i.e. Zr, ZrC and ZrCN, deposited on NiTi shape memory alloy by magnetron sputtering are investigated and compared to those of electropolished NiTi shape memory alloy. The Zr(C,N) series films have deteriorated wettability but have positive effects on the blood compatibility and cytocompatibility of NiTi. Better haemolysis resistance and thromboresistant properties are observed. There are more living cells on the Zr(C,N) series films, and the cells show a higher relative growth rate value than those on the electropolished NiTi. The Zr(C,N) series films act as barrier layers and promote the proliferation of fibroblasts by blocking the leaching of toxic nickel ions from NiTi.

Microstructural characteristics and biocompatibility of a Type-B carbonated hydroxyapatite coating deposited on NiTi shape memory alloy

Microstructural characteristics and biocompatibility of a Type-B carbonated hydroxyapatite (HA) coating prepared on NiTi SMA by biomimetic deposition were characterized using XRD, SEM, XPS, FTIR and in vitro studies including hemolysis test, MTT cytotoxicity test and fibroblasts cytocompatibility test. It is found CO(3)(2-) groups were present as substitution of PO(4)(3-) anions in HA crystal lattice due to Type-B carbonate. The growth of Type-B carbonated HA coating in SBF containing HCO(3)(-) ions is stable during all periods of biomimetic deposition. The carbonated HA coating has better blood compatibility than the chemically-polished NiTi SMA. There was a good cell adhesion to this HA coating surface and cell proliferation in the vicinity of the coating was better than that for the chemically-polished NiTi SMA. Thus biomimetic deposition of this carbonated HA coating is a promising way to improve the biocompatibility of NiTi SMA for implant applications.

Microstructure and properties of ZrTiC(N) composite films on NiTi alloy

Abstract The microstructure, blood biocompatibility and corrosion resistances, and mechanical properties of multinary ZrTiCN and ZrTiC composite films are investigated and compared to those of ZrCN film, ZrC film and NiTi shape memory alloy. The quaternary ZrTiCN and ternary ZrTiC composite films with ZrC and TiC as the predominant phases have a poor crystallinity but a higher adhesion strength with the NiTi substrate than both ZrCN and ZrC films due to the increased deposition temperature and the presence of TiC/TiN phases. Both coatings can improve the surface mechanical properties of biomedical NiTi shape memory alloy while simultaneously offering distinct advantages such as improved blood biocompatibility and corrosion resistances.

Effects of H2O2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

Abstract The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA) were investigated by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF) soaking test. It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3, Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment. As a result, the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF, which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.