현태환 교수

The synthesis of highly crystalline and monodisperse gamma-Fe(2)O(3) nanocrystallites is reported. High-temperature (300 degrees C) aging of iron-oleic acid metal complex, which was prepared by the thermal decomposition of iron pentacarbonyl in the presence of oleic acid at 100 degrees C, was found to generate monodisperse iron nanoparticles. The resulting iron nanoparticles were transformed to monodisperse gamma-Fe(2)O(3) nanocrystallites by controlled oxidation by using trimethylamine oxide as

Abstract Various inorganic nanoparticles have been used as magnetic resonance imaging (MRI) contrast agents due to their unique properties, such as large surface area and efficient contrasting effect. Since the first use of superparamagnetic iron oxide (SPIO) as a liver contrast agent, nanoparticulate MRI contrast agents have attracted a lot of attention. Magnetic iron oxide nanoparticles have been extensively used as MRI contrast agents due to their ability to shorten T2* relaxation times in th

Recent advances in the synthesis of various magnetic nanoparticles using colloidal chemical approaches are reviewed. Typically, these approaches involve either rapid injection of reagents into hot surfactant solution followed by aging at high temperature, or the mixing of reagents at a low temperature and slow heating under controlled conditions. Spherical cobalt nanoparticles with various crystal structures have been synthesized by thermally decomposing dicobalt octacarbonyl or by reducing coba

Various magnetic nanoparticles have been extensively investigated as novel magnetic resonance imaging (MRI) contrast agents owing to their unique characteristics, including efficient contrast effects, biocompatibility, and versatile surface functionalization capability. Nanoparticles with high relaxivity are very desirable because they would increase the accuracy of MRI. Recent progress in nanotechnology enables fine control of the size, crystal structure, and surface properties of iron oxide na

Synthesis of uniform nanocrystals is very important because the size uniformity of an ensemble of nanocrystals is directly related to the homogeneity of their chemical and physical properties. Classical theory suggests that burst nucleation and diffusion-controlled growth are the most important factors for the control of the size distribution in colloidal synthesis. In the last two decades, the numerous reports on the synthesis of uniform nanocrystals have popularized two major synthetic methods

Computed tomography (CT) is one of the most widely used clinical imaging modalities. In order to increase the sensitivity of CT, small iodinated compounds are used as injectable contrast agents. However, the iodinated contrast agents are excreted through the kidney and have short circulation times. This rapid renal clearance not only restricts in vivo applications that require long circulation times but also sometimes induces serious adverse effects related to the excretion pathway. In addition,

Core/shell upconverting nanoparticles (UCNPs) of NaGdF4:Er3+,Yb3+/NaGdF4 (see figure) are shown to serve as a multimodal imaging probe that works for both background-free optical imaging and magnetic resonance imaging (MRI). The nonblinking and nonbleaching properties of UCNPs can contribute to minimization of possible artifacts in long-term imaging experiments. Owing to Gd3+ ions in the host matrix, contrast is enhanced in T1-weighted MRI.

Lanthanide-doped upconverting nanoparticles (UCNPs) have recently attracted enormous attention in the field of biological imaging owing to their unique optical properties: (1) efficient upconversion photoluminescence, which is intense enough to be detected at the single-particle level with a (nonscanning) wide-field microscope setup equipped with a continuous wave (CW) near-infrared (NIR) laser (980 nm), and (2) resistance to photoblinking and photobleaching. Moreover, the use of NIR excitation

Dual-modal in vivo tumor imaging and photodynamic therapy using hexagonal NaYF(4):Yb,Er/NaGdF(4) core-shell upconverting nanoparticles combined with a photosensitizer, chlorin e6, is reported. Tumors can be clearly observed not only in the upconversion luminescence image but also in the magnetic resonance image. In vivo photodynamic therapy by systemic administration is demonstrated under 980 nm irradiation.

Carbon nanocoils with nanometer-thick graphitic fibers (see picture) were synthesized by the simple heat treatment of nanocomposites of a carbon precursor, silica, and a transition-metal salt. The carbon nanocoils exhibited a high surface area and a highly graphitized structure. The nanocoils were then successfully applied as catalyst supports for direct methanol fuel cell electrodes. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2

Highly crystalline and monodisperse cobalt ferrite nanocrystals were fabricated by the high-temperature aging of a metal-surfactant complex followed by mild oxidation. Particle sizes were varied from 4 to 9 nm by changing the experimental conditions. Transmission electron microscopic (TEM) images of the particles showed two- and three-dimensional assembly of the particles, demonstrating the uniformity of the nanocrystals. Electron diffraction, X-ray diffraction, and high-resolution transmission