Imaging Processes Using Core-Shell Particle Colloid Solutions for Medical Diagnosis

This paper describes our studies on development of methods for preparing colloid solutions of core-shell particles composed of core of materials with imaging ability and shell of silica that is inert to living bodies, and on their imaging properties. The methods for silica-coating are based on hydrolysis and condensation of silicone alkoxide in the presence of particles. AgI nanoparticles fabricated by mixing AgClO4 aqueous solution with KI aqueous solution were silica-coated with an aid of silane coupling agent. The silica-coated AgI particle colloid solution revealed X-ray imaging ability. Au nanoparticles, which were produced with reduction of HAuCl4 using citrate as reducing reagent and then surface-modified with silane coupling agent, were coated with silica. Images of the colloid solution were successfully taken through X-ray irradiation. For Gd compound, silica nanoparticles fabricated by a Stöber method were coated with Gd compound shell by a homogeneous precipitation method, and then coated with silica shell. The colloid solution was successfully imaged through magnetic resonance. Commerciallyavailable Cd-related semiconductor nanoparticles were surfacemodified with silane coupling agent, and then coated with silica. Tissues of mouse were imaged by injecting their colloid solution and using an in vivo fluorescence imaging system (IVIS).