X-ray computed tomography contrast agents prepared by seeded growth of goldnanoparticles in PEGylated dendrimer

Abstract

Gold nanoparticles (Au NPs) are a potential x-ray computed tomography (CT) contrastagent. A biocompatible and bioinactive surface is necessary for application of goldnanoparticle to CT imaging. Polyethylene glycol (PEG)-attached dendrimers have beenused as a drug carrier with long blood circulation. In this study, the Au NPs weregrown in the PEGylated dendrimer to produce a CT contrast agent. The AuNPs were grown by adding gold ions and ascorbic acid at various equivalentsto the Au NP-encapsulated dendrimer solution. Both size and surface plasmonabsorption of the grown Au NPs increased with adding a large number of gold ions.The x-ray attenuation of the Au NPs also increased after the seeded growth.The Au NPs grown in the PEG-attached dendrimer at the maximum under ourconditions exhibited a similar CT value to a commercial iodine agent, iopamidol,in vitro. The Au NP-loaded PEGylated dendrimer and iopamidol were injectedinto mice and CT images were obtained at different times. The Au NP-loadedPEGylated dendrimer achieved a blood pool imaging, which was greater thana commercial iodine agent. Even though iopamidol was excreted rapidly, thePEGylated dendrimer loading the grown Au NP was accumulated in the liver.