OICC Press Journal of Nanostructure in Chemistry 2193-8865 3 1 (December 2013) 2013 08 02 X-ray imaging technique using colloid solution of Au/silica core-shell nanoparticles 10.1186/2193-8865-3-62 EN Yoshio Kobayashi Department of Biomolecular Functional Engineering, College of Engineering, Ibaraki University, Ibaraki, 316-8511, JP Hiromitsu Inose Department of Biomolecular Functional Engineering, College of Engineering, Ibaraki University, Ibaraki, 316-8511, JP Tomohiko Nakagawa Division of Surgical Oncology, Graduate School of Medicine, Tohoku University, Sendai, Miyagi 980-8574, JP Yohsuke Kubota Division of Surgical Oncology, Graduate School of Medicine, Tohoku University, Sendai, Miyagi 980-8574, JP Kohsuke Gonda Division of Surgical Oncology, Graduate School of Medicine, Tohoku University, Sendai, Miyagi 980-8574, JP Noriaki Ohuchi Division of Surgical Oncology, Graduate School of Medicine, Tohoku University, Sendai, Miyagi 980-8574, JP Journal Article 2013 08 02 Abstract This work describes X-ray imaging of mouse using a colloid solution of silica-coated Au (Au/SiO 2 ) nanoparticles. A colloid solution of Au nanoparticles with a size of 16.9 nm was prepared using hydrogen tetrachloroaurate (III) trihydrate as Au source and sodium citrate as reducing reagent. Silica coating of the Au nanoparticles was performed by modifying the Au nanoparticle surface with (3-aminopropyl)trimethoxysilane and then by depositing silica nuclei generated through a sol–gel reaction of tetraethyl orthosilicate in water/ethanol initiated with sodium hydroxide on the surface-modified surface, which produced Au/SiO 2 particles with a size of 136.4 nm. A computed tomography value of the Au/SiO 2 colloid solution with an Au concentration of 0.036 M was as high as 1,184.8 Hounsfield units, which was quite higher than that of a commercial X-ray contrast agent with the same iodine concentration as the Au concentration. Tissues of mouse could be imaged by injecting the Au/SiO 2 particle colloid solution into them.