Size-Dependent Biodistribution of lodinated Oil Nanoemulsions Observed by Dual-Modal Imaging in Rats.

Sizes of nanoscale contrast agents play an important role in targeting specific organs and distribution in organisms. lodinated oil nanoemulsions with uniform size distribution and containing indocyanine green (ICG) fluorescent dye (25 nm, 60 nm, 100 nm) were synthesized by stirring, combined with ultrasonic emulsification technique. Rats were intravenously injected with the iodinated oil nanoemulsions with different sizes, used as contrast agents, and investigated with enhanced computed tomography (CT) and fluorescence imaging. Through experiments, the distribution and metabolism of the contrast agents in rat's bodies were studied, and their influence on enhanced CT imaging of different organs was compared. The results demonstrated that target accumulating organs for the iodinated oil nanoemulsions were liver and spleen, with obvious dosage-dependence. Large sized nanoemulsion preferred to accumulate into spleen, and liver, and the phagocytosis was getting weaker with the decrease of the nanoemulsion size. The CT imaging of the inferior vena cava was rapidly enhanced and reached the highest point after administration of the nanoemulsion. The nanoemulsion gradually gathered and metabolized in the spleen and liver, resulting in rapidly decreased CT imaging, with weak rebound, of the inferior vena cava.