Pure HA Research Articles

A study on calcium phosphate/barium titanate composites: phase characterization, piezoelectric property, and cytocompatibility

A series of hydroxyapatite/barium titanate (HA/BT) and tricalcium phosphate/barium titanate (TCP/BT) composites were prepared in various mixing ratios and sintered at temperatures between 500 and 1300 °C using the powder metallurgy method. Sintering was performed under different atmospheres to evaluate the effect of the atmosphere on the phase stability of the composites. BT phase showed slightly higher phase stability in TCP/BT composites than in HA/BT composites. BT with low concentration behaved as a stabilizer of α-TCP. A reaction between HA and BT occurred at about 900 °C yielding byproducts of CaTiO3 and Ba2TiO4, at the expense of both HA and BT phases. CaTiO3 and Ba2TiO4 phases associated with low BT concentrations were observed in the composites sintered at temperatures between 1100 and 1300 °C. The HA/BT composites having BT concentrations less than 95 wt.% did not show any measurable piezoelectric response. Composites with BT promoted osteoblast adhesion even better than pure HA and TCP.

Valorization of phosphate waste rocks to Ag3PO4/hydroxyapatite for photocatalytic degradation of Rhodamine B under visible light irradiation.

A silver phosphate/hydroxyapatite (Ag3PO4/HA) composite was produced from phosphate waste rocks, firstly by the valorization of these wastes to HA and then by the treatment of this prepared HA with a silver nitrate solution. A type of response surface methodology, Box-Behnken experimental design, was used to find optimum synthesis parameters (silver to HA weight ratios, calcination temperature and calcination time). The visible light photodegradation of Rhodamine B in aqueous solution was used as the experimental response. The analysis of variance for the results showed that silver weight ratio is the most influential parameter on photoactivity of the synthesized photocatalyst. The optimum conditions were predicted to give an RhB degradation yield of 98.609%/4 hours under visible light conditions. In this context, a Ag/HA weight ratio of 14%, a calcination temperature of 300 °C, and a calcination time of 30 min were found to be the optimum conditions. Samples synthesized under the optimum condition were characterized by the use of X-ray diffraction, X-ray fluorescence spectrometer, Fourier transform infrared spectrum analysis, scanning electron microscopy, transmission electron microscopy and ultraviolet-visible diffuse reflection spectroscopy. By comparison with pure HA, the characterization results clearly showed the successful synthesis of the Ag3PO4/HA composite.

Influence of Yttria Stabilized Zirconia and Hydrothermal Treatment on Plasma Sprayed Hydroxyapatite Coatings

A post-treatment of hydrothermal process was conducted to evaluate its effects on the material characteristics and mechanical properties of plasma-sprayed pure HA and HA/20% YSZ coatings. Surface morphology and microstructural changes, relative element contents as well as phase transformations were analyzed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry. Both microhardness and Young’s modulus were measured. CaCO3 was found existing before and after the whole process of post-treatment. Peaks of impurity phases such as CaO, TCP, and TTCP of as-sprayed coatings were observed to disappear while HA peaks show a tendency of getting higher and wider over time. Surface morphology of SEM analysis presents a clear deposition behavior of ultrafine HA crystallized particles and cross-sectional analysis exhibits a dense and fine structure. Mechanical properties of HA/20%YSZ coatings are found to be significantly higher than those of pure HA coatings and both of which displayed an overall increase with the heating time, indicating enhanced performances.

A Comparative Study of Pressureless Sintered Nanostructured Hydroxyapatite/TiO₂ Composites Prepared by Different TiO₂ Addition Methods.

Two methods of TiO₂ addition were applied to prepare hydroxyapatite/TiO₂ (HA/TiO₂) composite, i.e., in-situ hydrolysis TiO₂ in HA powders (N-HA/TiO₂) and mixing commercial nano-sized HA and TiO₂ powder (C-HA/TiO₂). Effects of TiO₂ addition methods and sintering temperatures on phase, microstructure and microhardness were investigated for pressureless sintered HA/TiO₂ composites, and pure HA was investigated for comparison. Results show that TiO₂ from both in-situ hydrolysis and mixing commercial powder presented similar effects on phase structures and composition, and trended to chemically react with HA in the HA/TiO₂ composites at high sintering temperature. Weight loss for different composites was investigated by thermal analysis. Sintering behavior for two different composite was also discussed. The TiO₂ from in-situ hydrolysis can effectively enhance the TiO₂ distribution and densification for the N-HA/TiO₂ composites. Both two different composites showed typical grain growth and pore formation with the increase of sintering temperature. The N-HA/TiO₂ composite had a lower porosity, higher shrinkage and microhardness than that of C-HA/TiO₂ composite at sintering temperature from 700 °C to 1100 °C.

Hydroxyapatite scaffolds containing copper for bone tissue engineering

The current study involves fabrication and characterization of HA scaffolds containing different copper (Cu) content by ion exchange and 3D extrusion deposition technique. The fabricated pure HA and Cu-doped scaffolds (Cu–HA) were characterized by mechanical behavior, SEM, EDS, XRD, and FT-IR studies. The results show that the Cu-doped HA scaffolds show stronger compressive strength. In addition, the antibacterial properties and biological properties of these scaffolds were investigated in vitro. The antibacterial test results show that the addition of Cu in the HA scaffolds increased antibacterial activity, and the antibacterial properties of scaffolds significantly increased with the addition of Cu. The biocompatibility test results show that the 15Cu–HA scaffolds treated with 15% CuSO4 curing solution significantly inhibited of cell growth on day 7, while the 5Cu–HA scaffolds treated with 5% CuSO4 curing solution the cells observed good grown state on day 7. The 5Cu–HA scaffolds show stronger mechanical behavior, increased antibacterial properties and lower toxicity rat bone marrow mesenchymal stem cells (BMSCs) on day 7. So, the developed 5Cu–HA scaffolds can be used as a good biomaterial for bone tissue engineering.

Synthesis of self-helix structure Si3N4 nanobelts and its reinforcement effect on HA coating

ABSTRACT A self-helix structure Si3N4 nanobelts reinforced hydroxyapatite (HSN/HA) coating has been synthesised on carbon/carbon composites by a combination method of catalyst-assisted pyrolysis of polymeric precursors and electrochemical deposition. The morphology, microstructure, and bonding strength of the coating were analysed. An individual Si3N4 nanobelt showed a self-helical shape. The bonding strength between HSN/HA coating and carbon/carbon composites reached 12.5 ± 0.72 MPa, higher than that of pure HA coating (6.38 ± 0.32 MPa). HSN/HA coating has the potential to apply to hard tissue substitution surgery in the future.

Si substituted hydroxyapatite nanorods on Ti for percutaneous implants

An ideal intraosseous transcutaneous implant should form a tight seal with soft tissue, besides a requirement of osseointegration at the bone-fixed position. Si substituted hydroxyapatite (Si-HA) nanorods releasing Si ion and simulating nanotopography of natural tissue were designed on Ti to enhance fibroblast response in vitro and biosealing with soft tissue in vivo. Si-HA nanorods were fabricated by alkali-heat treatment followed with hydrothermal treatment. The hydrothermal formation mechanism of Si-HA nanorods was explored. The surface characteristic of Si-HA nanorods was compared with pure HA nanorods. Fibroblast behaviors in vitro and skin response in vivo on different surfaces were also evaluated. The obtained results show that the substitution of Si did not significantly alter the phase component, morphology, roughness and wettability of HA, but additional Si and more Ca were released from Si-HA into medium. Comparing to pure HA nanrods and Ti substrate, Si-HA nanrods enhanced cell behaviors including proliferation, fibrotic phenotype and collagen secretion in vitro, and reduced epithelial down growth in vivo. The enhanced cell response and biosealing should be due to the releasing of Ca, Si and nanotopography of Si-HA nanorods. Si-HA nanorods can be a potential coating to accelerate skin integration for percutaneous implants in clinic.

Wollastonite ve Hidroksiapatit Kaplı Zirkonya İmplant Materyalinin Bağlantı Dayanıklılığı ve Biyoaktivitesinin Değerlendirilmesi

Objective: Zirconia dental implants are an alternative to titanium. Various studies have been carried out in order to improve the surface properties of zirconia implants like titanium implants. The aim of this study is to evaluate the resistance and bioactivity of zirconia dental implant materials coated with different ratios of hydroxyapatite and wollastonite powders by plasma spray method. Material and Methods: The bond strength between the zirconia and the coatings was measured according to the ASTM C-633 standard. The data were obtained by using one-way analysis of variance. Differences between the groups were determined by Post Hoc Tukey HSD test. Examples prepared for bioactivity testing were kept in 37 oC simulated body fluid for 2, 7, 14- and 21-day periods. Changes in the sample surfaces were analyzed by scanning electron microscopy using energy distribution x-ray spectrometry and x-ray diffraction device. Result: Bonding values of coatings containing different ratios of W were found to be significantly higher than pure HA coatings (p<0.05). Conclusion: All sample groups used in the study showed bioactive properties in simulated body fluid.

Influence of doping chromium ions on the electrical properties of hydroxyapatite

ABSTRACT Hydroxyapatite Ca10[PO4]6[OH] is a biocompatible widely used in medicine and dentistry. Its applications depend greatly upon lattice substitution of Calcium sites in its structure by varies cations such as Na, Mg, Sr, Ag etc. Chromium plays an important role in reducing blood sugar level and improving insulin ability to convert glucose in cells to gain energy. In this paper we studied the effect of doping hydroxyapatite with chromium ions on its crystal dielectric properties. Pure hydroxyapatite and chromium loaded hydroxyapatite of chromium concentrations of 0.5, 1.0, 2.0, and 3.0 wt % forming samples S1, S2, S3 and S4 respectively were prepared by wet precipitation method. The dielectric parameters, permittivity ἐ, dielectric loss ἕ, conductivity σ, relaxation time ts and dielectric modulus M’ and M’’ were calculated at frequency of 20 Hz to 10 MHz. Results showed increase of ἐ, and ἕ, values of chromium loaded samples compared to pure hydroxyapatite. The conductivity of the doped samples was increased with chromium concentration increase. The relaxation times (ts) chromium loaded samples showed increase of ts as chromium concentration increase. The dielectric properties showed that as chromium concentration increase, ἐ, ἕ, and σ of substance increase compared to the pure HA.

Fabrication of gelatin/hydroxyapatite/3D-graphene scaffolds by a hydrogel 3D-printing method

In this study, we demonstrate the fabrication of three-dimensional reduced graphene oxide/hydroxyapatite (HA)/Gelatin scaffolds by employing two steps, including a hydrothermal autoclave with hydrogen gas injection to synthesize three-dimensional graphene (3DG)/HA powders and a hydrogel 3D-printing method to fabricate the scaffolds. Evaluations were performed separately for synthesized powders and fabricated scaffolds, which included field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, Raman spectroscopy, and instrumented compression experiments. The powders characterization results showed that the nanostructured hybrid powders were successfully synthesized. The graphene sheets were stacked in 3D and the HA nanorods were attached on the surface of the graphene. Interface analysis showed that the two phases (HA/Graphene) are connected coherently and various preferential directions played a role in the growth of hydroxyapatite crystals. Characterization of the scaffolds showed that the addition of HA and graphene/HA powders resulted in smaller pores and higher dimensional accuracy of the fabricated scaffolds. Mechanical evaluation showed that the addition of HA (0.3 gr) increased the mechanical properties of the scaffolds. Also, increasing the small amount of graphene (0.0045 gr) made the mechanical properties much higher than that of pure HA.

Carbon Nanotube Reinforced Hydroxyapatite Nanocomposites As Bone Implants: Nanostructure, Mechanical Strength And Biocompatibility.

PurposeHydroxyapatite (HA) is a biologically active ceramic which promotes bone growth, but it suffers from relatively weak mechanical properties. Multi-walled carbon nanotubes (MWCNTs) have high tensile strength and a degree of stiffness that can be used to strengthen HA; potentially improving the clinical utility of the bone implant.MethodsHA was precipitated by the wet precipitation method in the presence of pristine (p) or functionalised (f) MWCNTs, and polyvinyl alcohol (PVA) or hexadecyl trimethyl ammonium bromide (HTAB) as the surfactant. The resulting composites were characterised and the diametral tensile strength and compressive strength of the composites were measured. To determine the biocompatibility of the composites, human osteoblast cells (HOB) were proliferated in the presence of the composites for 7 days.ResultsThe study revealed that both the MWCNTs and surfactants play a crucial role in the nucleation and growth of the HA. Composites made with f-MWCNTs were found to have better dispersion and better interaction with the HA particles compared to composites with p-MWCNTs. The mechanical strength was improved in all the composites compared to pure HA composites. The biocompatibility study showed minimal LDH activity in the media confirming that the composites were biocompatible. Similarly, the ALP activity confirmed that the cells grown on the composites containing HTAB were comparable to the control whereas the composites containing PVA surfactant showed significantly reduced ALP activity.ConclusionsThe study shows that the composites made of f-MWCNTs HTAB are stronger than pure HA composites and biocompatible making it a suitable material to study further.

The correlation between the methylation of PTEN gene and the apoptosis of osteosarcoma cells mediated by SeHA nanoparticles

The invasive spreading of residual osteosarcoma cells becomes a serious threat to human health, urgently needing new bone regenerative biomaterials for orthopedic therapy. Thus, in this work, selenite-substituted hydroxyapatite (SeHA) nanoparticles were prepared for both inhibiting the recurrence of the tumor and accelerating the regenerative repair of bone defect. Physicochemical characterization showed these synthetic nanoparticles were spherical poly-crystals with the shape of snowflakes. Such structure benefited them to inhibit the cellular viability of osteosarcoma cells by about (58.90 ± 14.37)% during 24 h co-culturing. The expression level of cell growth-related genes such as PTEN, MMP-9, Cyclin D1, Cyclin A2, Annexin A2 and CDC2 decreased. Bisulfite Sequence PCR of PTEN gene exhibited about (22.40 ± 5.39)%, (45.91 ± 6.36)% and (25.90 ± 5.36)% promoter methylation in control, HA and SeHA group. Animal experiment also proved the similar effects. Almost no recurrence were observed in SeHA group. Oppositely, the slowly recurrent growth of the remnant tumor appeared in purely surgical group. The overall survival and toxicity analysis showed that, in the usage dose of 0–0.1 g, the SeHA-0.01 exhibited higher inhibitory recurrence and metastasis potentials, lower renal toxicity and better anti-inflammation function. Immunohistochemistry stain showed the reduced expression of PTEN, MMP-9, Ki-67 and Annexin A2, but slightly increased expression of DNMT1 and BMP-2. Compared the methylation status of PTEN gene in each group, it was confirming that SeHA nanoparticles hardly possessed the de-methylation effect, but the pure HA strikingly increased the methylation level of such gene. It seemed the dopant selenite ions possessed de-methylation effect onto PTEN gene. Therefore, from the viewpoint of inhibiting metastatic potentials, the SeHA-0.01 might be a feasible biomaterial to inhibit the relapse of the tumor post-surgery.

Porous clinoptilolite—nano biphasic calcium phosphate scaffolds loaded with human dental pulp stem cells for load bearing orthopedic applications

Clinoptilolite (Cpt)-nanohydroxyapatite (HA) (Cpt-HA) scaffolds were fabricated as a potential material for loadbearing orthopaedic applications. Cpt-HA materials were successfully synthesized by using microwave assisted reflux method followed by the fabrication of three-dimensional (3D) porous scaffold via thermal decomposition process using polyethylene glycol (PEG)/ polyvinyl alcohol (PVA) as porogens. The scaffold materials were characterized using x-ray diffraction, Fourier transform Infra-red, Scanning electron microscopy and Energy dispersive spectroscopy techniques. Incorporation of Cpt in HA scaffold significantly increased the compressive strength and surface hardness while scaffolds retained an interconnected porous structure with 64% porosity. Human dental pulp stem cells (DPSCs) were isolated from the third molar and used as pluripotent-like cell model to evaluate the biological properties of Cpt-HA scaffolds. Highest cellular attachment and proliferation were observed for DPSCs seeded on 2.0 g Cpt-HA scaffolds compare to pure HA. Similarly, significantly higher ALP activity of cells was observed on Cpt-HA scaffolds compared to pure HA. The enhanced proliferation and osteogenic response of the DPSCs cultured on Cpt-HA scaffolds suggest that the fabricated scaffolds can be used in bone tissue engineering. In this work, we have successfully shown that the interconnected porous Cpt-HA scaffolds have superior mechanical biological properties compared to pure HA scaffold.

Biological Response to Macroporous Chitosan-Agarose Bone Scaffolds Comprising Mg- and Zn-Doped Nano-Hydroxyapatite.

Modification of implantable scaffolds with magnesium and zinc for improvement of bone regeneration is a growing trend in the engineering of biomaterials. The aim of this study was to synthesize nano-hydroxyapatite substituted with magnesium (Mg2+) (HA-Mg) and zinc (Zn2+) (HA-Zn) ions in order to fabricate chitosan-agarose-hydroxyapatite (HA) scaffolds (chit/aga/HA) with improved biocompatibility. Fabricated biomaterials containing Mg2+ or Zn2+ were tested using osteoblasts and mesenchymal stem cells to determine the effect of incorporated metal ions on cell adhesion, spreading, proliferation, and osteogenic differentiation. The study was conducted in direct contact with the scaffolds (cells were seeded onto the biomaterials) and using fluid extracts of the materials. It demonstrated that incorporation of Mg2+ ions into chit/aga/HA structure increased spreading of the osteoblasts, promoted cell proliferation on the scaffold surface, and enhanced osteocalcin production by mesenchymal stem cells. Although biomaterial containing Zn2+ did not improve cell proliferation, it did enhance type I collagen production by mesenchymal stem cells and extracellular matrix mineralization as compared to cells cultured in a polystyrene well. Nevertheless, scaffolds made of pure HA gave better results than material with Zn2+. Results of the experiments clearly showed that modification of the chit/aga/HA scaffold with Zn2+ did not have any positive impact on cell behavior, whereas, incorporation of Mg2+ ions into its structure may significantly improve biocompatibility of the resultant material, increasing its potential in biomedical applications.

Micro-arc oxidation of bioceramic coatings containing eggshell-derived hydroxyapatite on titanium substrate

In the present study eggshells-derived hydroxyapatite (EHA) coatings were successfully produced on Ti6Al4V substrates using micro-arc oxidation process (MAO) at various concentrations of EHA (i.e. 1, 1.5 and 2 g/L) in an electrolyte consisting of tri-sodium orthophosphate. The attributes of the coatings were determine by X-ray diffraction, attenuated total reflectance-fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. The adhesion strength was evaluated using micro scratch tester, while the corrosion behavior of the MAO-coated substrates in phosphate buffer solution was determined by an electrochemical method. The results showed that as the EHA concentration increased, this was accompanied by a reduction in the porosity due to the formation of a dense and thick coating layer. This has also resulted in an increased in the surface roughness and degree of crsytallinity of the HA phase. The MAO-coated substrate prepared with 1.5 g/L EHA concentration exhibited a well-formed coating layer with improved adhesive strength and excellent corrosion resistance. The mechanism of EHA-coating formation as well as the enhanced corrosion resistance of the coated substrates were discussed. This research shows the viability of using calcium-rich waste eggshells to produce phase pure HA suitable for coating on Ti6Al4V substrate using MAO method.

Cytocompatibility and Dielectric Properties of Sr2+ Substituted Nano-Hydroxyapatite for Triggered Drug Release

Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramics material used in medical applications because of its ability to form direct chemical bonds with living tissues. In this context, we investigate the biocompatibility and dielectric properties of Sr2+-substituted hydroxyapatite nanoparticles were synthesized by sol-gel method. The influence of strontium on the crystal structure, functional group, morphological, electrical properties, and biocompatibility of as-synthesized nano-hydroxyapatite samples was analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM). Dielectrical properties of the bioactive Sr-HA sample were investigated by a dielectric impedance spectroscopy method. The observed results illustrate the incorporation of Sr2+ ions in the apatite lattice could influence the pure HA properties, by reducing the crystallite size and crystallinity quite consistent with the morphology variation. The ac conductivity (σac) increased with an increasing applied frequency confirmed that prepared HA sample exhibited the universal power law nature. Further, the in vitro drug loading and release studies using doxycycline as a model drug demonstrate that the Sr2+ -HA nanoparticles show high drug adsorption capacity and sustained drug release. Thus, the improved bioceramics system could be a promising candidate for future biomedical applications.

Magnetic Silicium Hydroxyapatite Nanorods for Enhancing Osteoblast Response in Vitro and Biointegration in Vivo.

Osteoblast behavior playing an important role in the biointegration of the Ti implant with host bone in vivo can be regulated by surface properties and magnetic field. In order to endow the Ti surface with good osteogenesis activity, Si monosubstituted and Fe and Si cosubstituted hydroxyapatite (HAp) nanorods were fabricated on microporous TiO2 by microarc oxidation (MAO) followed with hydrothermal treatment (HT). The surface properties including microstructure, microroughness, hydrophilicity, ion release, magnetic property, cytocompatibility, and biointegration of substituted HAp nanorods were observed and evaluated, together with pure HAp nanorods and microarc oxidated (MAOed) TiO2 as controls. After being doped with Fe, MAOed TiO2 has no changes in phase composition and microroughness, whereas it displays weakly ferromagnetic behavior and can enhance osteoblast differentiation in vitro and formation of new bone in vivo, compared with the undoped one. The substituted HAp nanorods adhere firmly to TiO2 and have almost the same wettability and microroughness but additional Si, Fe, and/or Ca released into the medium, compared with pure HAp nanorods. Moreover, the cosubstituted HAp has a small ferromagnetic signal, while its saturation magnetization value is less than that of the MAOed doped with Fe. Compared to pure HA nanorods, the substituted HAp nanorods not only improve cell proliferation and differentiation in vitro, but also enhance the ability of bone integration in vivo, especially for the cosubstituted one, which should be ascribed to the combined effect of microstructure, magnetic property, and released ions.

Ascorbic Acid-Assisted Microwave Synthesis of Mesoporous Ag-Doped Hydroxyapatite Nanorods from Biowaste Seashells for Implant Applications.

Post-surgery implant infection is one of the most challenging issues in orthopedics and it is mainly caused by infective micro-organisms. A potential approach to overcome this issue is developing biomaterials with efficient antibacterial activity. The main intention of this present research is devoted to ascorbic acid-assisted microwave synthesis of mesoporous (silver) Ag-doped hydroxyapatite (HAp) nanorods using biowaste seashells with antibacterial properties. XRD, FTIR, and Raman spectroscopy results revealed that the synthesized nanoparticles are hexagonal crystalline HAp. Further, the silver-doped HAp was also successfully produced without affecting the HAp crystalline phase by forming electrostatic interaction with PO43- ions during the synthesis. The morphological features confirm that the pure HAp is elongated mesoporous nanorods with 20 nm width and 300-500 nm length. However, silver doped HAp nanoparticles such as AgHA-1, AgHA-2, and AgHA-3 are found to be similar mesoporous rods but with different aspect ratios in sizes of 15, 10-15, and 5-10 nm width and 80-100, 10-15, and 20-30 nm length. The BET specific surface areas were obtained as 29 ± 3, 84 ± 2, 87 ± 2, and 128 ± 3 m2 g-1, and pore diameters were 4.68, 4.18, 9.30, and 3.77 nm, respectively, for pure HA, AgHA-1, AgHA-2, and AgHA-3. Therefore, HAp nanoparticles with different dimensions and mesoporous structures could be rapidly prepared using a microwave-assisted method and ascorbic acid as a supporting material. In addition, the synthesized HAp nanoparticles are analyzed for its antibacterial and cytotoxicity studies. The antibacterial and cytotoxicity study clearly reveals that the Ag-doped HAp nanorods are efficiently antibacterial and nontoxic in nature. Hence, it is clear that the ascorbic acid-enabled microwave-assisted method will be one of the best methods for the rapid production of HAp nanoparticles with different dimensions and mesoporous structures for its application as an implant material.

Synthesis and characterization of nanocoatings derived by sol–gel onto a new surgical titanium surface

Surface coating of titanium (Ti) and its alloys with bioceramic materials is one of the main surface modification techniques used for developing different properties required for biomedical applications like mechanical strength, biocompatibility and corrosion behavior. In this work, pure HA and composite HA/TiO2 bioceramic coatings were prepared and deposited successfully on the surface of new biomedical Ti-Zr-Nb alloy system by sol-gel method. In order to investigate the surface properties of uncoated and coated substrates, various surface examinations were made such as surface topography, thickness, morphology and phase transformations. Furthermore, wear and corrosion properties of uncoated and coated substrates were also evaluated. The results displayed that the composite HA/TiO2 film can be considered as a potential thin film favorable for hard tissue application as it possesses an advanced crystallization and homogeneous nano-scale structure with outstanding wear and corrosion properties.

Fracture Properties and Failure Analysis of Zirconia Toughened Hydroxyapatite Bioceramic Coating

In order to improve the weak mechanical properties of bioceramic HA, composite coatings were prepared by adding the toughening zirconia to HA powder so as to improve the biological and the physical properties but not to reduce the biocompatibility of HA bioceramic coating. The pure HA coating and HA/ZrO2 composite coating containing 30% stabilized zirconia on titanium alloy by employing plasma spraying technology were prepared. The relation curves of load-displacement for the two coatings were obtained with three point bending experiment, and obtained the slope about the straight fitting line. Then the elastic modulus and fracture toughness of the both coatings were calculated. The fracture morphology of the two coatings after their failure was observed using electron microscope.