Nanostructured hydroxyapatite (HAP) was prepared by a wet precipitation method using Ca(NO 3 ) and KH 2 PO 4 as the main material and NH 3 as the precipitator under ultrasonic irradiation. The Ca/P ratio was set at 1.67 and the pH maintained at a minimum of 9. The temperature conditions and ultrasound influences were investigated using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that Nano-HAP can be obtained by this method and the particles were achieved to around 30nm.

Hydroxyapatite (HAP) is a widely used biocompatible ceramic in many biomedical applications and devices. Currently nanometer-scale forms of HAP are being intensely investigated due to their close similarity to the inorganic mineral component of the natural bone matrix. In this study nano-HAP was prepared via a wet precipitation method using Ca(NO 3 ) 2 and KH 2 PO 4 as the main reactants and NH 4 OH as the precipitator under ultrasonic irradiation. The Ca/P ratio was set at 1.67 and the pH was maintained at 9 during the synthesis process. The influence of the thermal treatment was investigated by using two thermal treatment processes to produce ultrafine nano-HAP powders. In the first heat treatment, a conventional radiant tube furnace was used to produce nano-particles with an average size of approximately 30 nm in diameter, while the second thermal treatment used a microwave-based technique to produce particles with an average diameter of 36 nm. The crystalline structure and morphology of all nanoparticle powders produced were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Both thermal techniques effectively produced ultrafine powders with similar crystalline structure, morphology and particle sizes.

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Hydroxyapatite (HAP) is a biocompatible ceramic that is currently used in a number of current biomedical applications. Recently, nanometre scale forms of HAP have attracted considerable interest due to their close similarity to the inorganic mineral component of the bone matrix found in humans. In this study ultrafine nanometre scale HAP powders were prepared via a wet precipitation method under the influence of ultrasonic irradiation. The resulting powders were compacted and sintered to form a series of ceramic pellets with a sponge-like structure with varying density and porosity. The crystalline structure, size and morphology of the powders and the porous ceramic pellets were investigated using advanced characterization techniques. The pellets demonstrated good biocompatibility, including mixed cell colonisation and matrix deposition, in vivo following surgical implantation into sheep M. latissimus dorsi.

Accepted ManuscriptThis is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Effect of Dilute Gelatine on the Ultrasonic Thermally AbstractA series of nano hydroxyapatite-gelatin composites with different dilute solutions of gelatin concentrations were synthesized by a thermally assisted low power ultrasonic irradiation method.The gelatine hydroxyapatite, (Gel-HAP) nanoparticles were prepared using Ca(NO 3 ) 2 and KH 2 PO 4 in the presence of gelatine in an aqueous solution. The synthesised products were heat treated between 100°C and 400°C. The effect of the addition of gelatin on the nucleation and growth of synthesised nano HAP was investigated. Characterisation was performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). The characterisation results indicate that gelatin has been appended to the nano HAP forming regular spherical shaped crystals of nano sized Gel-HAP.

Background: Hydroxyapatite is generally considered a viable substitute for bone in a number of medical procedures such as bone repair, bone augmentation and coating metal implants. Unfortunately, hydroxyapatite has poor mechanical properties that make it unsuitable for many load bearing applications.Methods: In the present work various grades of finely crushed Pinctada maxima (pearl oyster shell) were combined with a nanometer scale hydroxyapatite powder to form novel composite materials. A comparative study was made between the various powder based composites synthesized. The crystalline structure and morphology of the various powder based composites were investigated using X-ray diffraction and field emission scanning electron microscopy. The composite materials were also evaluated and characterized.Results: Manufactured hydroxyapatite powders were composed of crystalline spherical/granular particles with a mean size of 30 nm. Also produced were hydroxyapatite and finely crushed calcium carbonate from Pinctada maxima (pearl oyster shell) powder mixtures. Hydroxyapatite coatings produced on Pinctada maxima nacre substrates were investigated and their surface characteristics reported.Conclusions: Pinctada maxima nacre pre-treated with sodium hypo chlorate before hydroxyapatite deposition produced a superior coating and could be used for bone tissue engineering. But further in vitro and in vivo studies are needed to validate the biocompatibility and long term stability of this composite coating.

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In this paper, synthesised nanometre sized hydro xyapatite (nano-HAP) powders co mposed of spherical 30 ± 5 nm part icles were co mpacted and sintered at temperatures ranging from 650 to 1250℃ to form ceramics of varying porosity and mechanical strength. The size, crystalline structure and morphology of both the synthesised nano-HAP particle powders and the compacted and sintered ceramics were investigated using both X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Fu rther characterisation techniques such as Brunauer-Emmett-Teller (BET) particle surface area, porosity, bulk density, Vickers hardness and yield strength at various sintering temperatures were tested on sintered pellets and evaluated.