Carbon-coated iron oxide nanoparticles as contrast agents in magnetic resonance imaging
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NANO EXPRESS
Open Access
Carbon-coated iron oxide nanoparticles as contrast agents in magnetic resonance imaging Hongsub Bae1, Tanveer Ahmad1, Ilsu Rhee1*, Yongmin Chang2, Seong-Uk Jin2 and Sungwook Hong3
Abstract Coprecipitated ferrite nanoparticles were coated with carbon using a hydrothermal method. From transmission electron microscope pictures, we could see that the coated iron oxide nanoparticles were spherical in shape with an average diameter of 90 nm. The strong bonding of carbon on the nanoparticle surfaces was checked by noting the C = O and C = C vibrations in Fourier transform infrared spectra. The spin-lattice relaxation process [T1] and spin-spin relaxation process [T2] relaxivities of hydrogen protons in the aqueous solution of coated nanoparticles were determined to be 1.139 (mM·s)-1 and 1.115 (mM·s)-1, respectively. These results showed that the carboncoated iron oxide nanoparticles are applicable as both T1 and T2 contrast agents in magnetic resonance imaging. PACS: 81.05.y; 76.60.Es; 61.46; 75.50.k; 87.61. Keywords: iron oxide nanoparticles, carbon-coated nanoparticles, relaxivity, MRI
Introduction Nanostructured materials have attracted a great deal of attention in the development of biotechnology and medicine [1-3]. Among these nanostructured materials, carbon-coated metal oxide nanoparticles such as MgO, CaO, ZnO, TiO2, Al2O3, and Fe2O3 are now extensively studied because of their high application potential [4-9]. Recently, much research interest has been expended on the ferromagnetic iron oxide materials generally used for magnetic data storage as magnetic toners in xerography, and on the ferrofluids, used as contrast agents in magnetic resonance imaging [MRI] [10-13]. The carbon coating provides an effective oxidation barrier and prevents corrosion in magnetic core materials. Hydrophilic carbon coating on iron oxide nanoparticle cores endows better dispersibility and stability than those shown by bare iron oxide nanoparticles. In general, different approaches have been employed for the synthesis of carbon coatings, for example, electric arc discharge, catalytic pyrolysis of organic compounds, and the hydrothermal methods [14]. In this paper, we report the synthesis of carbon coating on iron oxide (Fe3O4) nanoparticles by a hydrothermal * Correspondence: [email protected] 1 Department of Physics, Kyungpook National University, Daegu, 702-701, Republic of Korea Full list of author information is available at the end of the article
method proposed by Zhang et al. [14] with some modifications. We evaluated these coated particles as potential spin-lattice relaxation process [T1] and spin-spin relaxation process [T2] contrast agent in MRI. We studied the T1 and T2 relaxations of hydrogen protons in water molecules in an aqueous solution of carbon-coated iron oxide nanoparticles. We found that the T1 and T2 relaxivities for the aqueous solution of carbon-coated iron oxide nanoparticles were 1.139 and 1.115 (mM·s) -1 , respectively. The ratio of these two relaxivities is close to unity. This re
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