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The rod-shaped synthesized by using co-precipitation and thermal decomposition method, respectively , for applying them as MRI contrast agents. The rod-shaped and spherical nanoparticles were coated with dextran and CTAB, respectively. The coated status was confirmed by FT-IR spectra. From TEM image the average length and width of the rod-shaped nanoparticles were 16.86 nm, 3.92 nm, respectively. The average diameter of the spherical nanoparticles was 9.40 nm. The XRD patterns of the nickel ferrite nanoparticles showed the inverse spinel ferrite crystalline structure. The magnetization of the nickel ferrite nanoparticles was measured by using a vibrating sample magnetometer. The rod-shaped nickel ferrite nanoparticles showed the paramagnetic behavior, while the spherical nanoparticles were super paramagnetic. The aqueous solutions of the nanoparticles with varying concentrations were prepared for MRI measurements. The particle concentration in the solutions was determined by using ICP. The relaxation times of the hydrogen protons in the aqueous solution were measured by using an MRI scanner. The T1 and T2 relaxivities were determined to be 0.62 and 1.58 mM-1 ·sec-1, respectively for the rod-shaped nanoparticles. On the other hand, the T1 and T2 relaxivities of the spherical nanoparticles were 0.57 and 10.42 mM-1 ·sec-1, respectively. Those results showed that the rod-shaped and spherical nickel ferrite nanoparticles can be used as T2 contrast agent, but the spherical nickel ferrite nanoparticles are more suitable for the T1 contrast agent. However, both nickel ferrite nanoparticles showed the possibility for using them as the T1 contrast agent.
Thesis Advisor: Prof. Ilsu Rhee