m khatamian

In this study, calcium nitrate tetrahydrate (Ca (NO3)2.4H2O) and phosphorus pentoxide (p < sub>2O5) were used to synthetize hydroxyapatite nanoparticles through the sol-gel method at the ambient temperature. In order to examine the structure and identify the chemical bonds and to compare them with the  intact tooth, X-ray diffraction analysis (XRD) and Fourier transform infrared spectrum (FT-IR) were used, respectively. Also, through scanning electron microscope (SEM) images, the microstructure and morphology of both synthesized hydroxyapatite nanoparticles and intact tooth were investigated. The results of X-ray diffraction analysis and Fourier transform infrared spectrum indicated  that the produced powder was  pure hydroxyapatite, i.e. without any discernible amount of impurity in the sample. Crystal structure of the synthesized hydroxyapatite was  nearly identical to the crystal structure of intact tooth; moreover,  the chemical bonds of the  intact tooth were also seen in hydroxyapatite. Furthermore, the synthesized sample featured a high degree of crystallinity. On the other hand, analysis of SEM images showed  that the morphology of the synthesized hydroxyapatite and intact tooth (with nanoscale dimensions and average particle size distribution of 25.69 nm and 23.15 nm, respectively), was almost spherical, thereby confirming the similarity of  the synthesized nanoparticle structure to thr intact tooth. In these images, the agglomeration of the synthesized nanoparticles was also seen. Compressive strength of the synthesized sample was equal to  5.5 MPa, which was approximately the same as that  of the  cancellous bone.

Magnetic resonance imaging (MRI) contrast agents have an important role to differentiate healthy and diseased tissues. Access and design new contrast agents for the optimal use of MRI are necessary. This study aims to evaluate iron oxide–4A nanocomposite ability to act as a magnetic resonance imaging contrast agent. Iron oxide–4A nanocomposite (F4A) was synthesized. MTT assay was used to consider the nanocomposite safety for cell culture. The T1 and T2 relaxation times were measured using a 1.5 Tesla clinical MRI scanner. Then the corresponding relaxivities were determined. The average particle diameter of the nanocomposite was 50 to 100 nm based on scanning electron microscope (SEM) image. A linear relationship between relaxation rates and the Fe concentration of the nanocomposite was obtained. The T1 and T2 relaxivities of the nanocomposite were calculated 5.413 and 1092.1 mM-1.s-1, respectively which led to the T2/T1 relaxivity ratioof 201.75. The high T2/T1 relaxivity ratio of the iron oxide–4A nanocomposite confirms it’s potential to act as a T2 contrast agent.