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Magnetic materials inside bone scaffolds are known to be a promoting factor for bone healing especially when the therapy is accompanied by application of external magnetic stimulation. In this study we employed a new route to synthesize iron oxide nanoparticles inside hydroxyapatite/chitosan bone scaffolds. Hydroxyapatite and chitosan are both natural compounds and were prepared from bovine cortical bone and shrimp shell, respectively. The morphology and composition of the synthesized materials were characterized employing scanning electron microscopy and FTIR spectroscopy. The iron oxide mean particle size inside the scaffold matrix was estimated to be in the range of 10–40 nm by particle size analyzer and transmission electron microscopy. The X-ray powder diffraction pattern indicated that the magnetite crystal size was about 23.5 nm. Magnetic measurements specified that the saturated magnetic intensity ( M s ) was approximately 3.04 emu/g and the coercive force was 128.39 Oe. The results revealed that the as-prepared magnetite was super-paramagnetic. [ABSTRACT FROM AUTHOR]

The main aim of the present study was to produce natural chitosan with different deacetylation degree from shrimp shells. Three deacetylation degrees of chitosan were obtained through boiling the chitin in NaOH (50% (w/v)) at 110 °C for 4 h. The samples were labelled as NCS1, NCS2 and NCS3 according to the number of times they were treated with alkaline solution. The functional groups of the obtained products and the degree of deacetylation were determined through Fourier transformed infra-red spectroscopy. Scanning electron microscope was employed to characterise the morphology of the produced materials. Cell viability assay was carried out using mesenchymal stem cells cultured on the samples for 7 days. The results showed that the deacetylation degree of chitin, NCS1, NCS2 and NCS3 became 50.1, 73.5, 82.3 and 82.5%, respectively. The natural chitin had carnation-like morphology. NCS1, NCS2 and NCS3 had the raised hills with the smaller and denser Gulbergs, however, there was no significant difference between NCS2 and NCS3 regarding the structure and deacetylation degree. Moreover, the result of the cell culture experiment indicated that the number of cells on the NCS1 was less than that of the NCS2 after 7 days. [ABSTRACT FROM AUTHOR]

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]