Synthesis of 99mTc‐labeled organo‐germanium nanoparticles and their in vivo study as a spleen imaging agent

^99mTc‐Labeled organo‐germanium nanoparticles ranging in size from 60 to 80 nm were newly developed for a spleen imaging agent. The radiolabeled nanoparticles were prepared with a high labeling efficiency (over 99%) and they also showed an excellent stability at room temperature for 6 h. The biodistribution data of the nanoparticles injected into rats via intravenous routes showed a notably higher accumulation in the spleen when compared to other reticuloendothelial system organs. Gamma image of the rabbits obtained after an intravenous injection of the nanoparticles revealed a localization of the radioactivity mainly in the spleen and the liver. Copyright © 2006 John Wiley & Sons, Ltd.