| Summary: | 博士 === 國立臺灣師範大學 === 化學系 === 98 === The controlled growth of alloy FePt nanostructures was investigated systematically. FePt octapod, cuboctahedron, and nanocube were successfully synthesized from a cuboctahedral seed and examined by the high-resolution transmission electron microscopy (HRTEM). In a solution reaction, the specific surfactant-facet bindings on the growth seed were generated and then, the growth rate of crystal facets on seed was differentiated by the djustments of reaction parameters. Therefore, the formations of FePt nanostructures were mainly attributed to the differences in the growth rate between the {111} and {100} planes of cuboctahedral seeds. In particular, the highest coercivity and blocking temperature of octapods are mainly due to its higher surface to volume ratio and more structural facets. On the other hand, the FeCo particles with different sizes were synthesized through controlling the reaction period. The process of Ostwald ripening was discovered in the FexCo1-x system due to the low lattice energy. Based on the XRD patterns, the transformation of structural phase and formation of magnetically dead layers was observed. Also, the saturated magnetization of FexCo1-x nanoparticles was influenced by their structural changes obviously.
Finally, the water-soluble nanoparticles with the sizes of 3, 6 and 12 nm in diameters were prepared and presented excellent biocompatibility and hemocompatibility. The bio-distribution analyses indicated that 3nm-FePt nanoparticles exhibited the highest brain concentration. Moreover, 12 nm-FePt nanoparticles exerted the highest circulation half-life and image contrast effect in the
in vitro CT/MRI test. Anti-Her2 antibody conjugated FePt nanoparticles demonstrated molecular expression dependent CT/MRI dual imaging contrast effect in MBT2 cell line and its Her2/neu gene knock out counterpart. The 12 nm-FePt outperformed 3nm-FePt in both imaging modalities. Selective contrast enhancement of Her2/neu overexpression cancer lesions in both CT and MRI was found in tumor bearing animal after tail vein injection of the nanoparticles. These results indicate the potential of FePt nanoparticles to serve as novel multi-modal molecular imaging contrast agents in clinical settings.
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