Size-control synthesis of structure deficient truncated octahedral Fe3-delta O4 nanoparticles: high magnetization magnetites as effective hepatic contrast agents

作者：Huang Chih Chia; Chuang Kuei Yi; Chou Chen Pin; Wu Ming Ting; Sheu Hwo Shuenn; Shieh Dar Bin; Tsai Chiau Yuang; Su Chia Hao; Lei Huan Yao; Yeh Chen Sheng^*

来源：Journal of Materials Chemistry, 2011, 21(20): 7472-7479.

DOI：10.1039/c1jm10325c

This study reports the size-controlled synthesis of truncated octahedral Fe3-delta O4 nanoparticles varying from 5 to 22 nm in edge length. Size-dependent XRD spectra show that the iron oxide gradually shifted from magnetite toward maghemite as the size decreased. The nonstoichiometric Fe3-delta O4 was expressed the resulting iron oxide nanoparticles. The smaller particle size resulted in larger delta value. The size dependence of the XRD, magnetization, and Raman measurements indicate that the 22 nm-sized particles formed magnetite nanoparticles. The saturation magnetization increased linearly as the particle size increased, eventually reaching 94 emu/g, which is comparable to bulk magnetite (92 emu/g). The magnetic behavior of Fe3-delta O4 nanoparticles exhibited a transition from superparamagnetism to ferromagnetism when the particles reached 22 nm in size. The XRD, electron diffraction analysis, fast Fourier transform filtering analysis, and Ar ion beam etching results in this study indicate that the presence of metallic iron in the 22 nm-sized magnetite nanoparticles was responsible for their high magnetization. The high magnetization of the 22 nm-sized magnetite was achieved by different surface modification strategies using surfactant (CTAB) and a polymer (PSMA), generating hydrophilic properties. The chosen PSMA-coated magnetites have an r(2) relaxivity larger than 200 mM(-1) s(-1), whereas the commercial Resovist hepatic agent achieves only 91 mM(-1) s(-1). In an effort to develop highly effective hepatic contrast agents, the PSMA-coated magnetite was injected into BALB/C mice to evaluate the T-2* relaxation and image contrast. Results show a greater signal reduction in the liver than Resovist agent. The biodistribution profile of these iron oxide nanoparticles shows significant liver uptake, which is consistent with MRI observations.

• 出版日期2011