Effect of fluorine addition on the biological performance of hydroxyapatite coatings on Ti by aerosol deposition
ABSTRACT Dense and well-adherent fluoridated hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2-x )F( x ), FHA] coatings with various amounts of fluorine contents (x = 0, 0.5, 1.0, 1.5, and 2.0) were deposited on commercially available pure titanium by aerosol deposition using FHA powders in order to investigate the effect of fluorine content on the properties of the coatings. FHA powders with different compositions were synthesized by solid-state reactions of hydroxyapatite (HA) and fluorapatite (FA) powders at various ratios. X-ray diffraction and Fourier transform infrared spectroscopy results showed that fluoride ions were successfully incorporated into the HA lattice for both the FHA powders and the FHA coatings. Scanning electron microscopy analysis revealed dense microstructures and good substrate adhesion of the coatings with high adhesion strengths of more than 33.1 MPa. The dissolution behavior in a tris-buffered saline solution indicated that the dissolution rate of the FHA coatings decreased as a result of increasing the fluorine content in the coatings. In addition, in vitro cellular tests, including cell attachment, proliferation, and alkaline phosphatase activity of MC3T3-E1 preosteoblast cells grown on the coatings, demonstrated that an FHA coating with a moderate degree of F(-) substitution, x = 1.0, had a stronger stimulating effect on cell proliferation and differentiation. These results suggested that there exists an optimum fluorine content level in the FHA coatings for the best long-term stability and cellular responses.
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ABSTRACT: Since various interactions among cells, surrounding tissues and implanted biomaterials always occur at their interfaces; the surface properties of potential implants appear to be of the paramount importance for the clinical success. In view of the fact that a limited amount of materials appear to be tolerated by living organisms, a special discipline called surface engineering was developed to initiate the desirable changes to the exterior properties of various materials but still maintaining their useful bulk performances. In 1975, this approach resulted in introducing of a special class of artificial bone grafts, composed of various mechanically stable (consequently, suitable for load bearing applications) implantable biomaterials and/or bio-devices covered by calcium orthophosphates (CaPO4) to both improve biocompatibility and provide an adequate bonding to the adjacent bones. Over 5000 publications on this topic were published since then. Therefore, a thorough analysis of the available literature has been performed and about 50 (this number is doubled, if all possible modifications are counted) deposition techniques of CaPO4 have been revealed, systematized and described. These CaPO4 deposits (coatings, films and layers) used to improve the surface properties of various types of artificial implants are the topic of this review.Materials Science and Engineering C 05/2015; 55. DOI:10.1016/j.msec.2015.05.033 · 2.74 Impact Factor
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ABSTRACT: We have successfully doped hydroxyapatite (HA) with barium (Ba2+) and fluoride (F–) ions to furnish Ca10– xBa x(PO4)6(OH)2– yF y, (where x = 0–1 and y = 1) by using microwave assisted wet precipitation method. The resulting powders were characterized by using X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer, Emmett and Teller (BET), and inductively coupled plasma optical emission spectrometry (ICP-OES) to study phase purity, particle morphology, elemental composition, specific surface area and in-vitro ion release. XRD analysis confirmed the formation of pure phase barium doped fluorine-hydroxyapatite with increased lattice parameters but with reduced degree of crystallinity. FESEM analysis confirmed the formation of spherical nanoparticles with homogenous distribution of elements with reduction in crystallite size when compared to HA, while BET results showed an increase in specific surface area upon increased degree of Ba doping. In-vitro bioactivity study carried out in SBF revealed that the incorporation of Ba2+ ions into HA structure lead to the faster release of Ca2+ ions resulting in faster formation of apatite layer.Science of Advanced Materials 02/2015; 7(2). DOI:10.1166/sam.2015.2103 · 2.91 Impact Factor
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ABSTRACT: The heterogeneous precipitation of calcium-phosphates on calcium hydroxyapatite (Ca10(PO4)6(OH)2 or HAP) in the presence and absence of fluoride is important in the formation of bone and teeth, protection against tooth decay, dental and skeletal fluorosis and defluoridation of drinking water. Strontium hydroxyapatite (Sr10(PO4)6(OH)2 or SrHAP) and strontium carbonate (SrCO3) were used as calcium-free seed templates in precipitation experiments conducted with varying initial calcium-to-phosphate (Ca/P) or calcium-to-phosphate-to-fluoride (Ca/P/F) ratios. Suspensions of SrHAP or SrCO3 seed templates (which were calcium-limited for both templates and phosphate-limited in the case of SrCO3) were reacted at pH 7.3 (25 °C) over 3 days. The resulting solids were examined with Scanning Transmission Electron Microscopy (STEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure (XANES), and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS). Calcium apatite was the predominant phase identified by all techniques independent of the added Ca/P ratios and of the presence of fluoride. It was not possible to make an unambiguous distinction between HAP and fluorapatite (Ca10(PO4)6F2, FAP). The apatite was calcium-deficient and probably contained some strontium.Journal of Crystal Growth 06/2014; 396:71–78. DOI:10.1016/j.jcrysgro.2014.03.036 · 1.69 Impact Factor