We report on the optoacoustic (OA) imaging of the whole mouse body using a biocompatible contrast agent - highly
purified, pegylated gold nanorods (GNR) - which has strong optical absorption in the near-infrared region and low level
of toxicity. In vitro toxicity studies showed no significant change in survival rates of the cultured normal epithelium
IEC-6 cells when incubated for 24 hours with up to 1 nM of GNR. In vivo toxicity studies in nude mice showed no
pathological changes in liver 1 month after the IV injection of GNR with intra-body concentration around 0.25-0.50 nM.
In order to study the enhancement of the OA contrast and accumulation of GNR in different tissues, we performed 3D
OA imaging of live nude mice with IV-injected GNR. The enhancement of the OA contrast in comparison with the
images of the untreated mice was visible starting 1 hour after the GNR injection. The OA contrast of kidneys, liver, and
spleen peaked at about 2-3 days after the administration of the GNR, and then was gradually reducing.
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