Gold nanorod distribution in mouse tissues after intravenous injection monitored with optoacoustic tomography

We used a three-dimensional optical tomogaphy system that was previously developed to create high contrast maps of optical absorbance of mice tissues. In this study, animals were scanned before and after injection of gold nanorods (GNRs) at different time periods. As-synthesized GNRs were purified from hexadecyltrimethylammonium bromide (CTAB) and coated with polyethylene glycol (PEG) to obtain GNR-PEG complexes suitable for in vivo applications. Intravenous administration of the purified GNR-PEG complexes to mice resulted in an enhanced contrast of normal tissues and blood vessels as compared to ordinary nude mice. In parallel with optoacoustic imaging we investigated the accumulation of GNRs in liver using invasive analytical techniques. Maximum levels of GNRs in liver macrophages were observed after 48-72 hours post-injection, followed by slow clearance trend after 8 days. Optoacoustic imaging revealed redistribution of GNR in mouse organ and tissues: in the initial hours, accumulation of GNRs is seen predominantly in the periphery of the mouse, while a gradual increase of GNR levels in liver, spleen and kidneys is seen in 1 and 24 hours.