| Summary: | 碩士 === 國立成功大學 === 化學系碩博士班 === 98 === We report the size-controlled synthesis of truncated octahedral Fe3-?O4 nanoparticles with sizes varying from 5 to 22 nm. Size-dependent XRD spectra showed that the iron oxide gradually shifted from magnetite toward maghemite as size decrease. The nonstoichiometric Fe3-?O4 was expressed the resulting iron oxide nanoparticles, where the cation vacancy numbers were deduced leading to ? increase as particle size decrease. Size dependence of XRD, magnetization and Raman measurements indicated that the 22 nm-sized particles displayed the formation of magnetite nanoparticles. The saturation magnetization increased linearly as the particle size increased, with values up to 94 emu/g, which is comparable to bulk magnetite (92 emu/g). XRD, electron diffraction including fast Fourier transform filtering analysis, and depth profiling XPS were conducted, indicating the presence of metallic iron in the 22 nm-sized magnetite resulting in high magnetization.
The high magnetization 22 nm-sized magnetite was engineered by different surface modification strategies using surfactant (CTAB) and polymer (PSMA) resulting in hydrophilic property. The chosen PSMA-coated magnetite have r2 relaxivity large than 200 mM-1s-1, where a commercial Resovist hepatic agent displays 91 mM-1s-1. Aiming to develop highly effective hepatic contrast agents, we injected the PSMA-coated magnetite into BALB/C mice to evaluate the T2* relaxation and image contrast. The results showed a greater signal reduction in liver as compared to Resovist agent.
Simultaneously, the PSMA-coated magnetite with fluorouracil (5-FU) can act as a candidate for drug delivery carriers. Combining theses biomedical effects into a Fe3O4@PSMA fluid system would be further developed into an ultra-sensitive of magnetic response and sensing for bionanomedical platform and applications.
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