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The aim of this research is to evaluate the mechanical properties and degradation behavior of the chitosan/hydroxyapatite/ferrite nanocomposites in the ringer solution. The initial materials, including chitosan and hydroxyapatite, were developed from shrimp shells and bovine cortical bone, respectively. Ferrite was also synthesized through wet-chemical method using FeCl 2 .4H 2 O and FeCl 3 .6H 2 O as precursors. The obtained results showed that the samples containing chitosan with a lesser deacetylation degree (73.5%) possess higher bending strength when compared to the samples with a higher deacetylation degree (82.5%). The samples with higher amounts of chitosan remain healthier and have a lesser weight loss percentage than the samples with more hydroxyapatite. The samples with the ratio of chitosan:hydroxyapatite (6:4) have displayed the smallest amount of degradation. Additionally, the samples with lower ratio of chitosan:hydroxyapatite (4:6) (the sample labeled as B) have demonstrated significantly higher fracture toughness (regarding to compression stress-strain curves) than other samples. Finally, it is concluded that chitosan/hydroxyapatite/ferrite nanocomposite with 6 g chitosan, 4 g hydroxyapatite, 0.5 g FeCl 2 .4H 2 O, and 1 g FeCl 3 .6H 2 O (the sample labeled as F) is selected as the optimal sample of this research, with regards to both of the mechanical properties and degradation behavior results. [ABSTRACT FROM AUTHOR]

The main goal of this research was the preparation and evaluation of the mechanical properties, in vitro biodegradability and cytocompatibility, of natural chitosan/hydroxyapatite/nano magnetite (nano-Fe 3 O 4 ) composite. Different ratios of these components were investigated, including chitosan/hydroxyapatite: 4/4 (S1), chitosan/hydroxyapatite: 4/6 (S2), and chitosan/hydroxyapatite: 6/4 (S3). Mechanical properties of fabricated composites were examined using bending and compression tests before immersion, and after 2 and 9 weeks of immersion in the Ringer's solution. Scanning electron microscope (SEM) was employed for observing the bending fracture surface and analyzing the degradation morphology. Human mesenchymal stem cells (hMSC) were also cultured on the samples in order to assess the cytocompatibility. The obtained results revealed that S1 had the highest bending strength before immersion, while S3 had the highest bending strength after 9 weeks immersion. Compressive strength of S2 was greater than that of S1 and S3 not only before immersion, but also after 9 weeks immersion. Although the bio-minerals were deposited on the surface of all samples during the immersion in Ringer's solution, S2 appeared to have the highest quantity of bio-minerals. According to the weight loss percentage (ΔW(%)), the biodegradation resistance of S1 was the lowest. Finally, the cytocompatibility of S1 was greater than that of S2 and S3. [ABSTRACT FROM AUTHOR]