![]() However, according to Scardi 11 and Piga et al. The structural properties of hydroxyapatite from several sources have been studied by X-ray diffraction, in which information about the determination of crystalline structures, crystalline quality, crystal size, and lattice defects can be obtained. In this direction, it was found that some commercial hydroxyapatites for clinical applications showed microcrystals that could be the result of high annealing temperatures 4. However, the nanometric crystal size as a requirement has not been explored. In the case of tissue engineering, some requirements are necessary for replacement materials among bioactivity, biocompatibility, biodegradability, osteoinductivity, enough mechanical properties, and a suitable architecture 10. One of them is the crystal size that is commonly determined through X-ray diffraction. The physicochemical properties of the isolated phase obtained by incineration depend on variables such as heating rate, annealing temperature, sintering time, cooling, and the atmosphere 6, 8, 9. Until now, several methods are widely used to isolate the mineral phase from the organic matrix of the bone: alkaline or acid hydrolysis, subcritical water process, and thermal decomposition (incineration) 7. The ions presence influences the structural, thermal, optical, and morphological properties of hydroxyapatite 6, and are very important for tissue engineering applications. But, the peaks for biogenic hydroxyapatites (BIO-HAps) are less sharp and broader which is attributable to the small size of crystals 5. Even with the presence of these ions, the XRD patterns of the raw bone mineral phase almost exhibit the same positions as those of synthetic hydroxyapatite 4. It is well established that the above-mentioned biogenic sources are formed by nanocrystals of HAp that contain s minor elements such as Mg, Na, S, and K. This misinterpretation could limit their potential uses. However, there is still a problem in the interpretation of their patterns concerning to the shape and width for raw and incinerated biogenic hydroxyapatite that are commonly used in clinical applications. The structure of these biogenic materials has been studied using X-ray diffraction (XRD). One of these is the hydroxyapatites (HAp) from biological sources such as human, bovine, and porcine due to their different applications 1, 2, 3. Nowadays, there is an increasing interest in nanomaterials in different fields such as tissue engineering. A simulation of the effect of the crystallite size on the shape and width of the X-ray patterns was done using PDF-4 software which confirmed that raw ordered bone crystals produce broad peaks which so far have been erroneously assigned to polycrystalline hydroxyapatite with low crystalline quality. The calcination of raw clean bones at 720 ☌ produced a transition of crystal size from nano to micro due to a coalescence phenomenon, this was accompanied by a decrease of the peak width of the X-ray diffraction patterns due to the decrease of the inelastic scattering contribution from the microcrystals. The nanometric size of the crystals was determined through High Resolution Transmission Electron Microscopy in which ordered crystals were found. ![]() Inductively Couple Plasma showed the presence of some ions such as Mg, K, Al, Fe, Zn, and Na for all samples. This paper focuses on the study of the effect of the change of the crystal size on the shape and width of the X-ray diffraction patterns for defatted and deproteinized bones as well as incinerated biogenic hydroxyapatite obtained from bovine, porcine, and human bones.
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