Papers by Keyword: Nanocrystalline Hydroxyapatite

Abstract: In this work, nanocrystalline hydroxyapatite (HAp) powders were synthesized through wet precipitation method by adjusting the reaction temperature between 0 °C and 5 °C. The influence of biologically active Mg and Sr addition on HAp crystalline structure and thermal behavior was assessed. In all synthesis, nanocrystalline and/or amorphous HAp was found to be the major phase, and was accompanied by Ca(OH)₂ as the minor phase. Results suggested that Sr and Mg have an impending effect on nucleation, crystallization and thermal stability of HAp. The addition of Sr or Mg promoted deviation from stoichiometry and formation of amorphous components, which affected thermal stability and sintering behavior of the synthesis products.

Abstract: In tussue engineering, hydrogel-based scaffold is one of the most common method for bone tissue engineering. Gelatin is a common material for scaffold, whereas hydroxyapatite (HA) has a similar composition and structure to natural bone mineral. HA can also increase cell adhesion ability of the scaffold. This research focuses on the fabrication of hydrogel scaffolds using gelatin composite with nanocrystalline hydroxyapatite (nHA). Then the mechanical and physical caharacteristics of the scaffold is investigetad. Low contents nHA is introduced into gelatin in order to modulate mesenchymal stem cell (MSC) behavior. There are three types of scaffolds which contain various HA content. The gelatin is crosslinked with glutaraldehyde before freeze-drying. The Young’s modulus of the surface is investigated using Atomic force microscopy (AFM). The pore size is investigated using scanning electron microscope (SEM). Human MSCs are culture on the scaffold for 3 weeks. The result shows the sucesse in cell cultivation. However, the human MSCs cultured on the fabricated hydrogels do not show any lineage-specific differentiation.

Abstract: Titanium with surface nanostructure has superior mechanical and biological properties, which benefits titanium implants. To further improve the bioactivity of Ti surfaces, Ca/P-containing porous titania coatings were prepared on Ti with surface nanostructure by ultrasonic shot peening (USP) and micro-arc oxidation (MAO). The phase identification, composition, morphology and microstructure of the coatings of Ti with surface nanostructure during MAO were investigated subsequently. The amounts of Ca, P and the Ca/P ratio of the coatings formed on Ti with surface nanostructure were greater than those on coarse-grained Ti. Incubated in a simulated body fluid, bone-like apatite was completely formed on the surface of Ti, thus evidencing preferable bioactivity.

Abstract: Mechanochemical process in polymeric vials has been carried out successfully to produce nanocrystalline hydroxyapatite (HAp) through two different reactions R1 and R2. Morphological properties and structural evaluation of obtained materials are studied by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM). The obtained data show that the increase in milling time leads the increasing in lattice strain and decreasing in crystallite size. The average crystallite size of HAp is below 20 and 23 nm for R1 and R2 reactions, respectively. Based on XRD patterns and SEM/TEM micrographs, the possible formation mechanism of nanocrystalline hydroxyapatite by mechanochemical process in polymeric milling media is confirmed. Final results indicate that the nanocrystalline hydroxyapatite with low chemically stable contaminations and suitable morphology can be produced in Polyamide6 vials similar to stainless steel vials, therefore it seems that using polymeric vials could lead to a new way for the mass production of nanocrystalline hydroxyapatite with high performance, low contamination and cost and also suitable morphology.