| Fabrication of Multi-Layered Gold-Silica-Gadolinium Compound Core-Shell Particles and their Applications to X-ray Imaging and Magnetic Resonance Imaging Yuta Shindo1; Tomoya Inose2; Noriko Yamauchi1; Kouichi Nakashima1; Masayuki Tokunaga2; Chihiro Kato2; Kohsuke Gonda2; Yoshio Kobayashi1; 1IBARAKI UNIVERSITY, Hitachi, Japan; 2TOHOKU UNIVERSITY, Sendai, Japan; PAPER: 6/Nanomaterials/Regular (Oral) SCHEDULED: 14:25/Sat. 26 Oct. 2019/Coralino ABSTRACT: Materials composed of components that have different properties should have multiple functions. Various composite particles with magnetism and X-ray absorption abilities have been developed. Based on the viewpoint for multi-functionalization of materials, particles containing gold (Au) and gadolinium compounds (GdC) will act as both the X-ray contrast agent and the MRI contrast agent. In our previous work [1], the silica (SiO<sub>2</sub>)-coating of metallic Au nanoparticles has been performed by using a modified Stober method. Our other previous works have proposed methods for GdC-coating particles such as the SiO<sub>2</sub> [2] and SiO<sub>2</sub>-coated quantum dot [3,4]. The present work proposes a method for preparing multi-layered core-shell particles composed of the core of Au, the first shell of SiO<sub>2</sub>, and the second shell of GdC (Au/SiO<sub>2</sub>/GdC), which is a combination of the various coating techniques developed in our previous works [1-4]. Imaging abilities based on both X-ray absorption and magnetic resonances of the multi-layered core-shell particle colloid solution were also studied in the present work. The Au nanoparticles were produced by reducing hydrogen tetrachloroaurate (III) trihydrate with trisodium citrate dihydrate. SiO<sub>2</sub>-coated Au (Au/SiO<sub>2</sub>) nanoparticles were fabricated by a sol-gel reaction in the presence of the Au nanoparticles. Multi-layered Au/SiO<sub>2</sub>/GdC nanoparticles were fabricated by a homogeneous precipitation reaction in the presence of Au/SiO<sub>2</sub> nanoparticles. The Au nanoparticles, the Au/SiO<sub>2</sub> nanoparticles, and the multilayered Au/SiO<sub>2</sub>/GdC nanoparticles had average sizes of 15.5, 38.0, and 43.8 nm, respectively. The computed tomography (CT) value of the Au/SiO<sub>2</sub>/GdC colloid solution containing 4.3x10<sup>-2</sup> M Au was 606 HU: Its converted CT value (CT value divided by Au concentration) was 1.4x10<sup>4</sup> HU M<sup>-1</sup>. The longitudinal relaxation rate (r1) of the Au/SiO<sub>2</sub>/GdC colloid solution was 2.3 mM<sup>-1</sup> s<sup>-1</sup>. In conclusion, the Au/SiO<sub>2</sub>/GdC colloid solution was found to function as the X-ray contrast agent and the MRI contrast agent. References: [1] Y. Kobayashi, H. Inose, T. Nakagawa, K. Gonda, M. Takeda, N. Ohuchi, A. Kasuya, J. Colloid Interface Sci. 358 (2011) 329-333.<br />[2] Y. Kobayashi, J. Imai, D. Nagao, M. Takeda, N. Ohuchi, A. Kasuya, M. Konno, Colloids Surf. A 308 (2007) 14-19.<br />[3] Y. Kobayashi, T. Nozawa, T. Nakagawa, K. Gonda, M. Takeda, N. Ohuchi, A. Kasuya, J. Sol-Gel Sci. Technol. 55 (2010) 79-85.<br />[4] Y. Kobayashi, T. Nozawa, M. Takeda, N. Ohuchi, A. Kasuya, J. Chem. Eng. Jpn. 43 (2010) 490-493. |
