HA/ZrO2 不同复合材料对MSCs贴壁、增殖及成骨分化影响的差异

目的: 观察间充质干细胞(MSCs)在不同生物材料表面的生长及成骨分化情况。方法: 采用干铺法制备氧化锆(ZrO₂)单层复合羟基磷灰石(HA)及ZrO₂梯度复合HA 两种复合材料,观察复合材料表面形貌特征。分离和培养兔MSCs,分别培养于HA/ZrO₂单层复合材料、HA/ZrO₂梯度复合材料、纯HA及ZrO₂材料薄片上,观察细胞贴壁、增殖情况和碱性磷酸酶活性,提取细胞总RNA并检测Ⅰ型胶原、骨钙蛋白和骨桥蛋白mRNA 表达情况。结果: 制备的HA/ZrO₂单层复合材料具有不连续的HA表面层,可以清晰地观察到部分ZrO₂基体。而HA/ZrO₂梯度复合材料表面较为粗糙,呈多孔状。X射线衍射分析显示,经高温烧结后,两种复合材料表面的ZrO₂相依旧存在,HA相转变为β-Ca₃(PO₄)₂(β-TCP)、α-Ca₃(PO₄)₂(α-TCP)和CaZrO₃相。细胞培养显示,HA/ZrO₂梯度复合材料更有利于细胞贴壁。细胞在纯HA上碱性磷酸酶活性较其它组显著升高;细胞在复合材料和纯HA上Ⅰ型胶原、骨钙蛋白和骨桥蛋白表达较对照组均有不同程度升高,其中Ⅰ型胶原表达升高更为明显。结论: HA/ZrO₂梯度复合材料可促进MSCs的增殖,并可促进MSCs的成骨分化。     

Effect of CaF2 on densification and properties of hydroxyapatite-zirconia composites for biomedical applications

Hydroxyapatite (HA) composites with zirconia (ZrO2) up to 40 vol% were fabricated with the addition of CaF2. The sinterability of the composites was found to be enhanced markedly by the addition of small amounts of CaF2 (< 5 vol%). Decomposition of HA to beta-TCP was suppressed due to the substitution of F- for OH-, consequently forming fluor-hydroxyapatite (FHA) solid solution. This suppression of decomposition allowed the production of a fully dense body, which retained both high flexural strength and fracture toughness. The osteoblast-like cell (MG63) response to these F- ion-containing composites displayed comparable cell viability to pure-HA by in vitro proliferation test.     

Sol-gel derived fluor-hydroxyapatite biocoatings on zirconia substrate

Fluor-hydroxyapatite (FHA) film was coated on a zirconia (ZrO(2)) substrate by a sol-gel method. An appropriate amount of F ions was incorporated into the hydroxyapatite (HA) during the preparation of the sols. The apatite phase began to crystallize after heat treatment at 400 degrees C, and increased in intensity above 500 degrees C. No decomposition was detected by X-ray diffraction analyses up to 800 degrees C, which illustrates the high thermal stability of the FHA films. The films showed a uniform and dense morphology with a thickness of approximately 1 microm after a precisely controlled heat treatment process. These FHA films adhered firmly to the zirconia substrate, representing notable adhesion strengths of approximately 70 MPa after heat treatment above 500 degrees C. The dissolution rate of the FHA coating layer varied according to the heat treatment temperature, which was closely related to the film crystallinity. The dissolution rate of the FHA film was lower than that of the HA film, suggesting the possibility of a functional gradient coating of HA and FHA. The MG63 cells seeded onto the FHA films proliferated in a similar manner to those seeded onto pure HA ceramic and a plastic control.     

Dissolution control and cellular responses of calcium phosphate coatings on zirconia porous scaffold

Different types of calcium phosphates [hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), and their composites (HA + FA, HA + TCP)] were coated on a zirconia (ZrO(2)) porous scaffold using a powder slurry method. The ZrO(2) porous scaffold was intended for a load-bearing implant, and the apatite layers were coated to improve osteoconductivity. The insertion of an FA intermediate layer between the coating layer and ZrO(2) scaffold effectively suppressed the reaction between the calcium phosphate and ZrO(2) and maintained the coating layer at the initial powder composition. The obtained coating layer, of a thickness of approximately 30 microm, was relatively microporous and firmly adherent to the ZrO(2) scaffold. Dissolution tests in physiological solution showed typical differences depending on the coating layers, with the dissolution rate increasing in the order TCP > HA + TCP > HA > HA + FA > FA. This result suggests the functional coating of the calcium phosphates in view of tailoring the solubility. Osteoblast-like cells, MG63 and HOS, responded similarly in terms of cell growth, morphology, and proliferation rate regardless of the coating types, indicating favorable and comparable cell viability. However, the alkaline phosphatase (ALP) activity of the cells on the pure HA and HA composite coatings (HA + FA and HA + TCP) expressed at higher levels compared to those on pure FA and pure TCP coatings for both MG63 and HOS cells, suggesting a selective cell activity depending on the coating types. All the calcium phosphate-coated-ZrO(2) scaffolds showed higher ALP levels compared to pure ZrO(2) scaffold.     

HA/ZrO2复合材料颗粒的体外基因毒性的初步研究

目的: 采用体外微核法评价HA/ZrO₂复合材料颗粒的基因毒性。方法: 按不同比例将羟基磷灰石与二氧化锆粉体混合在高温高压下烧结制备HA/ZrO₂复合材料颗粒,纯HA和纯ZrO₂颗粒作为对照。制备复合材料颗粒的悬液,分离和培养兔间充质干细胞。MTT法检测复合材料颗粒悬液对兔间充质干细胞增殖促进作用,体外微核试验(MNT) 检测复合材料颗粒悬液对兔间充质干细胞的基因毒性。结果: MTT实验显示:纯HA和含HA的复合材料颗粒均对间充质干细胞增殖有一定促进作用,而纯ZrO₂颗粒对间充质干细胞增殖没有促进作用,差异显著(P<0.05)。MNT实验显示:HA组与阴性对照组相比差异不显著(P>0.05),与阳性对照组比差异显著(P<0.05); ZrO₂组与阴性对照组比差异显著(P<0.01),与阳性对照组比差异不显著(P>0.05)。结论: HA/ZrO₂复合材料颗粒的基因毒性随着ZrO₂比例和复合材料浓度的增加而增加,30%wtHA/70%wtZrO₂在200 mg/L时具有显著基因毒性(P<0.01)。     

Novel carbon fiber composite for hip replacement with improved in vitro and in vivo osseointegration

A novel composite femoral stem has been developed to match cortical stiffness and achieve fixation by osseointegration with the primary goal to reduce cortical bone loss associated with stress shielding. The femoral stem consists of three distinct material layers: the first is a long carbon fiber (CF) in a polyamide 12 (PA12) polymer matrix (PA12/CF); the second is a PA12/HA (hydroxyapatite) interface; and the third is a plasma-sprayed coating of HA. In vitro studies with MG63 cells indicated that the HA surface supported improved proliferation and differentiation of osteoblast-like cells as determined by alkaline phosphatase activity and osteocalcin production when compared with Ti-6Al-4V (Ti64). In vivo studies comparing the composite and Ti64 rods in the rabbit femur demonstrated significantly higher bone apposition to the composite than Ti64 rods. The results of this study indicate that the invasion of surrounding bone cells and thus osteointegration together with its bone-matching mechanical properties make the PA12/CF/HA stem a promising hip replacement candidate.     

Effects of incorporation of HA/ZrO(2) into glass ionomer cement (GIC)

Glass ionomer cements (GICs) are a class of bioactive cements that bond directly to bone. In this paper, a new bioactive hydroxyapatite (HA)/zirconia (ZrO(2))-filled GIC composite was developed to improve the biocompatibility and bioactivity of the GICs with the surrounding bone and connective tissues. Nano-sized HA/30 wt% ZrO(2) powders were heat treated at 700 degrees Celsius and 800 degrees Celsius for 3 h to elucidate the influence of the crystallinity of composite powders on the performance of HA/ZrO(2)-GICs. The effects of different volume percentages of HA/ZrO(2) powders (4, 12, 28 and 40 vol%) substituted within GICs were investigated based on their microhardness, compressive strength and diametral tensile strength. The HA/ZrO(2)-GICs composite was soaked in distilled water for 1 day and 1 week before subjecting the samples to mechanical testing. Results showed that the glass and HA/ZrO(2) particles were distributed uniformly in the GIC matrix. The substitution of highly crystalline HA/ZrO(2) improved the mechanical properties of the HA/ZrO(2)-GICs due to the slow resorption rate for highly crystalline powders in distilled water. The mechanical properties of HA/ZrO(2)-GICs increased with increasing soak time due to the continuous formation of aluminium salt bridges, which improved the final strength of the cements. The compositions 4 and 12 vol% HA/ZrO(2)-GICs exhibited superior mechanical properties than the original GICs. The mechanical properties of HA/ZrO(2)-GICs were found to be much better than those of HA-GICs because ZrO(2) has the attributes of high strength, high modulus, and is significantly harder than glass and HA particles. Furthermore, ZrO(2) does not dissolve with increasing soaking time.     

Osteoblastic cell response on fluoridated hydroxyapatite coatings

Fluoridated hydroxyapatite (FHA) coatings were deposited onto Ti6Al4V substrates by sol-gel dip-coating method. X-ray photoelectron spectroscopy results showed that fluoride ions were successfully incorporated into the hydroxyapatite (HA) lattice structure. The dissolution behavior in Tris-buffered physiological saline indicated that all fluoridated HA coatings had lower solubility than that of the pure HA coating. The lowest solubility was obtained at fluoride ion concentrations of 0.8-1.1M. In vitro cell responses were evaluated with human osteosarcoma MG63 cells in terms of cell morphology, proliferation and differentiation (alkaline phosphatase activity and osteocalcin level). For all coatings tested, similar cell morphologies and good cell viability were observed. Coatings fluoridated to 0.8-1.1 had a stronger stimulating effect on cell proliferation and differentiation activities. The influences on cell phenotypes were attributed mainly to a combined ion effect of Ca, P and F released from the coating during dissolution. For the best dissolution resistance and cell activities, it is recommended that the molar level of fluoride ion be from 0.8 to 1.1, such that the coating takes the form of Ca(10)(PO(4))(6)(OH)(1.2-0.9)F(0.8-1.1).     

Hydroxyapatite and fluor-hydroxyapatite layered film on titanium processed by a sol-gel route for hard-tissue implants

A double-layered coating, consisting of a hydroxyapatite (HA) outer film and a fluor-hydroxyapatite (FHA) inner film, was produced on a Ti substrate by a sol-gel route to improve the biocompatibility and functionality of the system. Dissolution behavior of and in vitro cellular responses to the layered film were investigated. Calcium nitrate and triethyl phosphite were used for calcium and phosphate precursors, respectively, and ammonium fluoride was added as a fluorine-ion source for FHA. The FHA layer was deposited on Ti by spin coating and subsequent heat treatment at 550 degrees C for 30 min in air, and then the HA layer was laid down over the FHA-coated Ti under the same conditions. After heat treatment, characteristic apatite structures and phases were developed on both FHA and HA films. The cross-section view of the HA/FHA film clearly showed a double-layered structure on Ti with each layer approximately 0.6-0.8-microm thickness. The coating layer was highly uniform and dense, and adhered to Ti substrate strongly with an adhesion strength of about 40 MPa. The in vitro solubility of the HA/FHA layered film in a physiological solution was between that of HA and FHA pure film, and the dissolution profile was quite biphasic, that is, an initial rapid period and a slowdown with increasing time, reflecting the gradient solubility of the fast HA outer structure/slow FHA inner structure. The human osteoblast-like HOS TE85 cells cultured on the HA/FHA layered film attached, spread, and grew favorably. The proliferation rate of the cells on the layered film was significantly higher (considered at p < 0.05 for n = 6) than that on Ti substrate and was similar to that on pure HA film. The alkaline phosphatase (ALP) activity and osteocalcin (OC) produced by the cells on the layered film were significantly higher (considered at p < 0.05 for n = 6) than those on Ti substrate. Moreover, the ALP and OC levels of cells on the layered film showed the trends of HA outer/FHA inner structure with respect to culture period, that is, HA initially and FHA later. These observations suggest that the HA/FHA layered film on Ti obtained by a sol-gel route possesses gradient functionality in terms of solubility and cellular responses, and find that those parameters can be tailored for specific use in hard-tissue implants.     

The effect of fluoride contents in fluoridated hydroxyapatite on osteoblast behavior

Fluoridated hydroxyapatite (FHA) discs with various fluoride contents (0-0.567 mol F(-)/mol) [corrected] have been used to investigate the effect of fluoride content on osteoblastic cell behavior. SAOS-3 rat osteosarcoma cells were cultured on FHA discs for different time periods. The cell behavior was examined in terms of cell attachment, proliferation, morphology and differentiation. The fluoride content in FHA discs strongly affected the cell activities. More cell attachment and proliferation were observed on the fluoride-containing FHA discs than on pure hydroxyapatite (HA). The fluoride content also affected the differentiation behavior of osteoblastic cells. Cells on FHA discs demonstrated a higher alkaline phosphatase (ALP) activity than those on pure HA after 2 [corrected] weeks of culturing. These results suggested that fluoride ions have a significant impact on different osteoblastic cell activities.     

Porous ZrO2 bone scaffold coated with hydroxyapatite with fluorapatite intermediate layer

Highly porous zirconia (ZrO(2)) bone scaffolds, fabricated by a replication technique using polymeric sponge, were coated with hydroxyapatite (HA). To prevent the chemical reactions between ZrO(2) and HA, an intermediate fluorapatite (FA) layer was introduced. The strength of the porous ZrO(2) was higher than that of pure HA by a factor of 7, suggesting the feasibility of ZrO(2) porous scaffolds as load-bearing part applications. The coated HA/FA layer, with a thickness of about 30 microm, was firmly adhered to the ZrO(2) body with a bonding strength of 22MPa. The osteoblast-like cells were attached and spread well on the coating layer throughout the porous scaffolds. The alkaline phosphatase activity of the proliferated cells on the HA/FA coated ZrO(2) was comparable to that on pure HA and higher than that on pure ZrO(2).     

The influence of titania/hydroxyapatite composite coatings on in vitro osteoblasts behaviour

The biocompatibility of titania/hydroxyapatite (TiO2 /HA) composite coatings, at different ratio obtained by sol-gel process, were investigated studying the behaviour of human MG63 osteoblast-like cells. The biocompatibility was evaluated by means of cytotoxicity and cytocompatibility tests. Cytotoxicity tests, i.e., neutral red (NR), MTT and kenacid blue (KB) assays, were performed to assess the influence of the material extracts on lysosomes, mitochondria and cell proliferation, respectively. Cell proliferation, some preliminary indications of cell morphology, alkaline phosphatase activity, collagen and osteocalcin production of MG63 cells, cultured directly onto TiO2/HA substrates, were evaluated. The results showed that these materials have no toxic effects. Cell growth and morphology were similar on all the materials tested: on the contrary, alkaline-phosphatase-specific activity and collagen production of osteoblasts cultured on TiO2/HA coatings were significantly higher than uncoated titanium and polystyrene of culture plate and were influenced by chemical composition of the coatings. In particular, TiO2/HA coating at 1:1 ratio (w/w) seems to stimulate more than others the expression of some differentiation markers of osteoblastic phenotype. TiO2/HA coatings resulted to be bioactive owing to the presence of hydroxyl groups detected on their surface that promote the calcium and phosphate precipitation and improve the interactions with osteoblastic cells.     

Alendronate-hydroxyapatite nanocomposites and their interaction with osteoclasts and osteoblast-like cells

The direct synthesis of hydroxyapatite in the presence of bisphosphonates is quite difficult due to the great affinity for calcium of these compounds, which are widely used in the treatment of pathologies related to bone loss. We recently developed a new method which allowed to synthesize alendronate-hydroxyapatite composite nanocrystals with a bisphosphonate content up to about 7 wt%. Herein we report the results of an in vitro study aimed to investigate the effects of alendronate incorporation into hydroxyapatite on bone cells response. Osteoblast-like MG63 cells and human osteoclasts were cultured on nanocrystals at different alendronate content (3.9, 6.2, 7.1 wt%). MG63 cells cultured on the composite nanocrystals display normal morphology, good proliferation and increased values of the differentiation parameters. In particular, when cultured on composites at relatively high alendronate contents, osteoblasts display increased values of alkaline phosphatase activity (ALP), collagen type I, and osteocalcin production, as well as significant decrease of matrix metalloproteinases (MMP-1 and MMP-13) production, with respect both to the control and to pure hydroxyapatite nanocrystals. It follows that the presence of alendronate enhances osteoblast activation and extracellular matrix mineralization processes, without any abnormal collagen degradation. The osteoclast number on the composite nanocrystals decrease indicating that the bisphosphonate exerts its inhibitory effect on osteoclast proliferation even when incorporated into hydroxyapatite.     

Comparison of plasma-sprayed hydroxyapatite coatings and zirconia-reinforced hydroxyapatite composite coatings: in vivo study

The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has been widely adopted because the HA coating can achieve the firmly and directly biological fixation with the surrounding bone tissue. However, the long-term mechanical properties of HA coatings has been concern for the long-term clinical application. Previous research showed that the concept of adding ZrO2 as second phase to HA significantly increased the bonding strength of plasma-sprayed composite material. The present work aimed to explore the biological properties, including the histological responses and shear strength, between the plasma-sprayed HA and HA/ZrO2 coating, using the transcortical implant model in the femora of canines. After 6 and 12 weeks of implantation, the HA coating revealed the direct bone-to-coating contact by the backscattered electron images (BEIs) of scanning electron microscope (SEM), but the osseointegration was not observed at the surface of HA/ZrO2 coating. For new bone healing index (NBHI) and apposition index (AI), the values for HA implants were significantly higher than that for HA/ZrO2 coatings throughout all implant periods. After push-out test, the shear strength of HA-coated implants were statistically higher than HA/ZrO2 coated implants at 6- and 12-week implantation, and the failure mode of HA/ZrO2 coating was observed at the coating-bone interface by SEM. The results indicate that the firm fixation between bone and HA/ZrO2 has not been achieved even after 12-week implantation. Consequently, the addition of ZrO2 could improve the mechanical properties of coatings, while the biocompatibility was influenced by the different material characteristics of HA/ZrO2 coating compared to HA coatings.     

Calcium phosphates and glass composite coatings on zirconia for enhanced biocompatibility

Calcium phosphates (CaP) and phosphate-based glass (P-glass, xCaO-(0.55-x) Na(2)O-0.45P(2)O(5) composition) composite coatings were obtained on a strong ZrO(2) to improve biocompatibility, the mechanical strength and biological activity. Hydroxyapatite (HA) and P-glass mixed powder slurries were coated on the ZrO(2) substrate, and subsequently heat-treated to obtain CaP- and P-glass composite coatings. The effects of glass composition (x=0.3, 0.4, 0.5 mol), mixing ratio of glass to HA (30%, 40%, 50% wt/wt), and heat treatment temperature (800 degrees C, 900 degrees C, 1000 degrees C) on the coating properties were investigated. After heat treatment, additional calcium phosphates, i.e., dicalcium phosphate (DCP) and tricalcium phosphate (TCP), were crystallized, resulting in the formation of triphasic calcium phosphates (HA-TCP-DCP) surrounded by a glass phase. The relative amounts of the crystalline phases varied with coating variables. The higher heat treatment temperature and glass amount, and the lower CaO content in the glass composition rendered the composite coatings to retain the higher amounts of TCP and DCP while the initial HA decreased. These appearance of additional crystalline phases and reduction of HA amount were attributed to the combined effects, i.e., the melting-crystallization of P-glass and the reaction between glass liquid phase and HA powder during thermal treatment. As a result of the glass phase in the composite coatings, their microstructures became much denser when compared to the pure HA coating. In particular, a completely dense structure was obtained at coating conditions with large amount of glass addition (50 wt%) at the glass composition of lower CaO content (0.3 mol CaO), and the following heat treatment above 800 degrees C for 2h. As a result, the adhesion strengths of the composite coating layers were significantly improved when compared to the pure HA coating. The highest strength of the composite coating was approximately 40 MPa, an improvement of approximately 80% with respect to the pure HA coating. The composite coatings showed much higher dissolution rates than the pure HA coating due to the newly formed crystallines (TCP and DCP) and the remaining glass phase. The osteoblast-like cells grew and spread actively on the composite coating samples. The proliferation numbers and alkaline phosphate (ALP) activities of the cells on the composite coatings were improved by approximately 30-40% when compared to Thermanox control and ZrO(2) substrate, and were comparable to the pure HA coating. These findings suggested that the CaP and P-glass composites are potentially useful for hard tissue coating system, due to their morphological and mechanical integrity, enhanced bioactivity, and favorable responses to the osteoblast-like cells.     

Hydroxyapatite and titania sol-gel composite coatings on titanium for hard tissue implants; mechanical and in vitro biological performance

Hydroxyapatite (HA) composites with titania (TiO2) up to 30 mol % were coated on a titanium (Ti) substrate by a sol-gel route, and the mechanical and biological properties of the coating systems were evaluated. Using polymeric precursors, highly stable HA and TiO2 sols were prepared prior to making composite sols and coatings. Coatings were produced under a controlled spinning and heat treatment process. Pure phases of HA and TiO2 were well developed on the composites after heat treatment above 450 degrees C. The HA-TiO2 composite coating layers were homogeneous and highly dense with a thickness of about 800-900 nm. The adhesion strength of the coating layers with respect to Ti substrate increased with increasing the TiO2 addition. The highest strength obtained was as high as 56 MPa, with an improvement of about 50% when compared to pure HA (37 MPa). The osteoblast-like cells grew and spread actively on all the composite coatings. The proliferation and alkaline phosphatase (ALP) activity of the cells grown on the composite coatings were much higher than those on bare Ti, and even comparable to those on pure HA coating. Notably, the HA-20% TiO2 composite coating showed a significantly higher proliferation and ALP expression compared to bare Ti (p < 0.05). These findings suggest that the sol-gel-derived HA-TiO2 composite coatings possess excellent properties for hard tissue applications from the mechanical and biological perspective.     

Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA, Ti alloy and YSZ components.     

Initial attachment of osteoblastic cells onto sol-gel derived fluoridated hydroxyapatite coatings

Initial cell attachment and spreading of anchorage-dependent cells onto the material surface are crucial concerns for the development of more effective implants. In this study, MG63 cells were employed to investigate the initial cell response to sol-gel derived fluoridated hydroxyapatite (FHA) coatings. Along with that, surface roughness, wettability, and protein adsorption were also characterized for those FHA coatings, respectively. It was observed that both the surface roughness and contact angle have a slight increase in response to the incorporation of more fluorine ions. All FHA coatings showed similar amount of adsorbed proteins (approximately 1.6 microg/cm(2)) upon testing in culture medium. Cell counting showed that no significant difference was observed for the amount of initially attached cells between HA and fluoridated HA coatings during the first 4 h culture. On the other hand, the well-spread cell on all prepared coating surface indicates that the incorporated fluorine ions have no adverse effect on cell spreading process. Therefore, it was suggested from this study that the prepared fluoridated hydroxyapatite coatings have comparable bioactivity to that of pure hydroxyapatite coating, and these results are meaningful for further investigation for application of FHA coatings.     

Nanofiber generation of hydroxyapatite and fluor-hydroxyapatite bioceramics

In this study, we produced hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) bioceramics as a novel geometrical form, the nanoscale fiber, for the biomedical applications. Based on the sol-gel precursors of the apatites, an electrospinning technique was introduced to generate nanoscale fibers. The diameter of the fibers was exploited in the range of a few micrometers to hundreds of nanometers (1.55 microm-240 nm) by means of adjusting the concentration of the sols. Through the fluoridation of apatite, the solubility of the fiber was tailored and the fluorine ions were well released from the FHA. The HA and FHA nanofibers produced in this study are considered to find potential applications in the biomaterials and tissue engineering fields.