الفهرس 
Abstract
Chapter 1 : introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
During the last decade considerable attention has been directed toward the use of synthetic nanocomposite materials to facilitate bone regeneration in orthopedic surgery. Bone itself is a true nanocomposite consists of inorganic mineral (hydroxyapatite) embedded in organic collagen. Therefore, the true challenge is to establish experimental methodologies to control the size and morphology as well as the crystallinity of hydroxyapatite nanoparticles by using natural and synthetic polymers. The success of synthesizing hydroxyapatite with controlled size and shape is considered as an ultimate goal to design tailored nanocomposites with enhanced biological performance upon their implantation. In the current study, different compositions of chitosan and electropolymerized acrylic acid were used as a matrix for the deposition of hydroxyapatite. It is found that hydroxyapatite nanoparticles have different morphologies (spherical and rod-like nanoparticles) and sizes ranged from 10 to 150 nm. Furthermore, changing the reaction temperature from -10 to 60oC during the precipitation of hydroxyapatite particles within the polymer matrices was found to be effective in controlling the size of the nanoparticles. Chitosan-polyacrylic acid-hydroxyapatite nanocomposites with composition of 12-18-70 wt% were found to have the highest values of compressive strength (65.8 MPa) compared to all other ratios. The biological activity of the nanocomposites that contain acrylic acid with higher weight percentage revealed an enhanced apatite layer deposition after immersion in simulated body fluid compared to nanocomposites that consist of only chitosan and hydroxyapatite. The results of this study suggest that the size and morphology of laboratory-made nanocomposites for bone healing can be controlled by changing either the reaction temperature or by in situ precipitating hydroxyapatite at room temperature in anionic and cationic polymers with different composition. The precise control over the physical and structural properties of hydroxyapatite-hydrogel nanocomposites in non-randomly manner mimicking the natural biological process is expected to have a great potential and performance as an implant materials for orthopedic and dentistry fields.