Papers by Author: You Tao Xie

Abstract: Abstract: Calcium silicate (CS) ceramics have good biocompatibility, high bonding strength with titanium alloy substrates, and are potential candidates for implant coating materials. The osteo-integration of coated implants with host bone tissue is greatly affected by the degradation of these coating materials in biological fluid. In this paper, zirconia adopted calcium silicate (CaO-ZrO2-SiO2, CZS) ceramic powder was synthesized. Plasma spraying was used to prepare the coating with Ti-6Al-4V as substrates. Human bone marrow-derived stromal cells (hBMSCs) culture system was used to evaluate the cytocompatibility of the CS and CZS coatings. Results showed that more cells were adhered to the CZS coating with high proliferation ratio than those on CS. The dissolution of CS and hereby elevated pH value were contributed to the decreased cell adhesion and proliferation.

Abstract: Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrates have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the low bonding strength between HA and Ti substrates is still problematic in the long-term implantation lifespan. In this paper, HA/Ta composite coatings with various Ta contents (20% and 60%) were fabricated by vacuum plasma spraying (VPS). The microstructure, phase composition of the coatings was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results revealed that the coatings had a rough surface and lamellar structure including some pores. ASTM C-633 standard was used for the measurement of bonding strength, which was found increasing with the increase of Ta contents in the composite coatings. The bonding strength of the composite coating containing 60% Ta (H4T6) reached to 37.2 MPa, which is about 1.9 times that of HA coating. In vitro bioactivity evaluated in simulated body fluids (SBF) showed that bonelike apatite layer was formed on the composite coatings surface, which indicated the good bioactivity of the HA/Ta composite coatings.

Abstract: Silicon coatings were prepared by vacuum plasma spraying (VPS) and air plasma spraying (APS) technologies. The samples were hydrothermally treated and then incubated in simulated body fluid (SBF) to evaluate their bioactivity and silicon wafer was used as control sample at the same time. The SBF test showed that a Ca-P layer was formed on the surface of silicon wafer and VPS-Si coating after immersion in SBF for certain time, indicating their improved bioactivity. Whereas no Ca-P layer was found on the surface of APS-Si coating. The results of X-ray photoelectron spectroscopy showed that the Si/O atomic ratio and chemical depth profiles of the silicon oxide films on the surface of silicon wafer, VPS-Si and APS-Si coatings were different. The results indicated that the bioactivity difference of silicon-based material resulted from the different composition of their surface. Hydrothermal treatment maybe a favorable method to improve the bioactivity of silicon-based material having silicon oxide of non-stoichiometric Si/O atomic ratio.

Abstract: Biomaterials with good biocompatibility and anti-bacterial property were becoming attractive to researchers, so we used the chemical method to produce anti-bacterial vacuum plasma sprayed titanium coatings and studied In vitro bioactivity, cytotoxicity and blood compatibility of the anti-bacterial coatings in this paper. In order to evaluate the bioactivity of the treated titanium coatings, the coatings were immersed in simulated body fluid (SBF). The treated titanium coatings showed good bioactivity in this experiment. Two different methods were used to assess the cytocompatibility of the treated titanium coatings. One was extract test; the other was direct contact test. The results indicated that cells spread and adhered well on the coatings. The blood compatibility of the coatings was evaluated by haemolysis ratios. The hemolysis ratios of the coatings were below 2%, indicating of nonhemolysis for the coatings.

Abstract: Failure of dental implant is often caused by specific pathogenic bacteria. In this paper, antibacterial HA coating was prepared by vacuum plasma spraying with silver loaded zirconium phosphate containing HA as feedstock. The antibacterial activity against Aa，Fn and Pg was evaluated using a film covering method. MTT colorimetric assay was used to measure cytotoxic effect of the antibacterial HA coatings. Results show that the HA coatings displayed significant antibacterial activity against Aa，Fn, Pg and no cytotoxicity to L929 murine cell lines when the content of silver-loaded zirconium phosphate antimicrobial is between 5wt% to 10wt%. The sensitivity of the bacteria to the antibacterial HA coating is in sequence of Pg >Fn >Aa.

Abstract: In this paper, antibacterial silver-containing hydroxyapatite coating was prepared by vacuum plasma spraying method and osteoblasts were seeded onto the surface of the coating to evaluate its cytocompatibility. The results indicated that the cells proliferated well on the samples, and the proliferation rate on the silver-containing hydroxyapatite coating was a little bit higher than that on the silver-free hydroxyapatite coating. The contact angle of water drop on the coating was measured, and it was found that the contact angles of the silver-containing hydroxyapatite coatings were smaller than the hydroxyapatite coating. The improvement of hydrophilicity for the silver-containing hydroxyapatite coating could be beneficial to the cells proliferation on its surface. It can be concluded that the addition of silver in the hydroxyapatite coating endowed the coating with antibacterial property while maintaining its excellent cytocompatibility.

Abstract: The in vitro attachment, spread, and proliferation behavior of osteoblast cells on the plasma-sprayed composite coating with 70wt% zirconia and 30wt% dicalcium silicate were studied. The composite coating shows good cytocompatibility. The human osteoblast cells attached, spread and proliferate well on the surface. The cytocompatibility of the coating was attributed to the incongruent dissolution of dicalcium silicate and the large amount of Si-OH functional groups produced on the surface. The released calcium and silicon ions are also positive to the proliferation of cells. All our results show that the composite coating possesses good cytocompatibility.

Abstract: TiO2 coatings on titanium alloy substrates were prepared by atmospheric plasma spraying using commercial nano-powders and followed by H2SO4 treatment. The bioactivity of coatings was evaluated by the simulated body fluid soaking test. Scanning electron microscopy and energy-dispersive X-ray spectrometry were used to characterize the surface morphologies and phase composition of the coating before and after soaking in simulated body fluid. The results obtained indicate that H2SO4-treated TiO2 coating can induce a bone-like apatite formation on its surface, however, no apatite appears on the surface of as-sprayed TiO2 coatings. The acid concentration and treated time affected the bioactivities of TiO2 coatings.