Chuan Xian Ding

Antibacterial activity and increased bone marrow stem cell functions of Zn-incorporated TiO2 coatings on titanium

In this work, zinc was incorporated into TiO2 coatings on titanium by plasma electrolytic oxidation to obtain the implant with good bacterial inhibition ability and bone-formability. The porous and nanostructured Zn-incorporated TiO2 coatings are built up from pores smaller than 5 μm and grains 20-100 nm in size, in which the element Zn exists as ZnO. The results obtained from the antibacterial studies suggest that the Zn-incorporated TiO2 coatings can greatly inhibit the growth of both Staphylococcus aureus and Escherichia coli, and the ability to inhibit bacteria can be improved by increasing the Zn content in the coatings. Moreover, the in vitro cytocompatibility evaluation demonstrates that the adhesion, proliferation and differentiation of rat bone marrow stem cells (bMSC) on Zn-incorporated coatings are significantly enhanced compared with Zn-free coating and commercially pure Ti plate, and no cytotoxicity appeared on any of the Zn-incorporated TiO2 coatings. Moreover, bMSC express higher level of alkaline phosphatase activity on Zn-incorporated TiO2 coatings and are induced to differentiate into osteoblast cells. The better antibacterial activity, cytocompatibility and the capability to promote bMSC osteogenic differentiation of Zn-incorporated TiO2 coatings may be attributed to the fact that Zn ions can be slowly and constantly released from the coatings. In conclusion, innovative Zn-incorporated TiO2 coatings on titanium with excellent antibacterial activity and biocompatibility are promising candidates for orthopedic and dental implants.

Plasma spray coatings in different nanosize alumina

Three kinds of nanostructured alumina coatings were prepared by air plasma spraying (APS). The microstructure of these coatings was characterized by SEM and X-ray diffraction (XRD). The surface roughness, porosity and microhardness of as-sprayed coatings were measured. The results indicated that the smaller the size of starting powder was, the better properties the coating possessed. The differences among phase analysis of these as-sprayed coatings could explain it.

Characterization of plasma-sprayed hydroxyapatite/TiO2 composite coatings

To enhance the bonding between hydroxyapatite (HA) coating and titanium alloy substrate, HA/TiO2 composite coatings have been fabricatedvia plasma spraying. Bonding strength evaluation, simulated body fluid tests, and cell culturein vitro were carried out to characterize the composite coatings. The results obtained showed that the addition of TiO2 to HA coating improved the bonding strength of the coating significantly. After being immersed in simulated body fluid (SBF) for a period, the surfaces of HA/TiO2 composite coatings were completely covered by carbonate-containing apatite, which indicated that the coatings possess good bioactivity. Thein vitro cell culture indicated good cytocompatibility for HA/TiO2 composite coatings.

Study on Silver-Containing HA Coatings Prepared by Vacuum Plasma Spraying

Vacuum plasma sprayed (VPS) hydroxyapatite (HA) coatings with silver-loaded zirconium phosphate antimicrobial have been prepared on titanium substrate. Antibacterial effects of the coatings were studied by bacteria culturing using Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn) and Actinobacillus actinomycetemcomitans (Aa) as microorganisms. Simulated body fluid (SBF) test was carried out to evaluate the bioactivity of the coatings as well. The results obtained showed that the coatings exhibited a marked antibacterial effect against Pg, Fn and Aa when the content of antimicrobial was equal to or more than 5%. The antibacterial capability of the coatings decreased in the following order: Pg, Fn, Aa. Bone-like apatite layer was formed on the silver-containing HA coatings after immersed in SBF, suggesting that their bioactivities were not affected obviously by the addition of silver-zirconium phosphate antimicrobial. This study indicated that silver-containing VPS HA coating is a prospective candidate as dental material.

Photocatalytic Performance of Plasma Sprayed TiO2-ZnFe2O4 Coatings

A novel TiO2−ZnFe2O4 coating was prepared by plasma spraying. The effects of spraying parameters and the composition of powders on the microstructure and surface morphology of plasma sprayed coatings are studied. The photocatalytic efficiency of the as-sprayed coatings was evaluated through the photo mineralization of methylene blue. It was found that TiO2 coatings can decompose methylene blue under the illumination of ultraviolet rays, and the degrading efficiency is improved with an increase in the content of FeTiO3 in the coatings. However, the presence of a large amount of ZnFe2O4 compound will substantially lower the photocatalytic efficiency of the TiO2−ZnFe2O4 coatings for the unfavorable photo-excited electron-hole transfer process.

Bioactivity of Plasma-Sprayed Diopside Coating In Vitro

A new bioceramic coating based on diopside was prepared by plasma spraying. The surface and cross-section microstructure of the coating were examined by scanning electron microscopy. The thermal expansion coefficient of the diopside coating measured by a dilatometer adapted to that of titanium alloy. The bond strength of the coating was about 32.5 MPa, which is higher than that of HA coatings used in orthopedics and dentistry. The bioactivity of diopside coating was evaluated in vitro. After 15 days soaking in simulated body fluid, an apatite layer was formed on the surface of the coating. The cytocompatibility was investigated by studying the behaviour of human osteoblast cultured directly onto the surface of the coating. MTT assay was performed to assess the influence of the coating on cell proliferation. The morphologies of the cell were observed by SEM after incubation for 1 and 7 days. The results obtained indicated that plasma sprayed diopside coating may be a suitable candidate for bone and dental implant.

In Vitro Bioactivity, Cytotoxicity and Blood Compatibility of Anti-Bacterial Vacuum Plasma Sprayed Titanium Coatings

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.

In Vitro Cytocompatibility of Silver-Containing Hydroxyapatite Coatings

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.

Surface Modification of Vacuum Plasma Sprayed Titanium Coating via Two Different Treatments

Vacuum plasma sprayed (VPS) Ti coatings were deposited and their surface modification processes were performed by NaOH solution treatment and alkali-heat-calcification respectively. The simulated body fluid test indicated that apatite was formed on the surfaces of Ti coatings. A net-like structure was observed on the surfaces of Ti coatings treated by alkali-heat-calcification, whose bioactivity is much better than that treated by NaOH aqueous solution simply.

Photo-Decomposition Property of Thermal Sprayed TiO2 Coatings

TiO2 is a promising photocatalyst due to its excellent photocatalytic activity, physical and chemical stabilities. Plasma spraying technology is good way to prepare for TiO2 coating. The effect of spraying parameters on photocatalytic performance was studied. The results showed that both the amount of unmelted particles and the porosity of as-sprayed TiO2 coatings increased with the increasing of Ar gas flow rate. And the external bias could improve TiO2 coating’s photocatalytical performance. The improvement degree is closed related its grain size and porosity.