Gold nanoparticles (Au NPs) with a high X-ray attenuation coefficient have a good potential in CT imaging applications. Here, we report the design and synthesis of Au NPs entrapped within
polyethylene glycol (PEG)-modified branched
polyethyleneimine (PEI) with varying the initial Au
salt/PEI molar ratios and with the remaining PEI surface
amines being acetylated for blood pool, lung
tumor and lymph node CT imaging. The formed unacetylated and acetylated PEGylated PEI-entrapped Au NPs (Au PENPs) were characterized via different methods. We show that the PEGylated PEI is an effective template to entrap Au NPs having a uniform size ranging from 1.7nm to 4.4nm depending on the Au
salt/PEI molar ratio. After optimization of the composition-dependent X-ray attenuation effect, we then selected {(Au0)100-PEI·NHAc-
mPEG} NPs for biological testing and show that the particles have good cytocompatibility in the given concentration range and can be used as a
contrast agent for effective CT imaging of the blood pool of rats,
lung cancer model of nude mice and lymph node of rabbits after
intravenous injection. For each application, the injected dosage of the particles was optimized. In addition, the {(Au0)100-PEI·NHAc-
mPEG} NPs could be excreted out of the body with time. Our results indicate that the formed Au PENPs with an appropriate composition and dosage hold a great promise to be used for CT imaging of various biosystems.