CT/fluorescence dual-modal nanoemulsion platform for investigating atherosclerotic plaques

Macrophages have become widely recognized as a key target for atherosclerosis imaging, since they contribute significantly to the progression of atherosclerosis. Dual-modal imaging contrast agents with unique X-ray computed tomography (CT) and optical imaging capabilities have great potential in disease diagnosis because of complementary combination of the high spatial resolution of CT with the high sensitivity of optical imaging. Here, a kind of quantum dots (QDs)-iodinated oil nanoemulsion of 80 nm was developed as a CT/fluorescence dual-modal contrast agent. Hydrophobic QDs were embedded in iodinated oil, which subsequently dispersed in water to form the oil-in-water nanoemulsion. The morphology and hydrodynamic size of the nanoemulsion were characterized, CT values and fluorescence properties were detected. Its cytotoxicity and affinity to three different cells were determined in vitro by MTT assay. In vitro Micro-CT and confocal microscopy cell imaging ability of the nanoemulsion were confirmed by co-incubating with murine macrophage cells and human liver cells. Then in vivo accumulation of this nanoemulsion in macrophages in atherosclerotic rabbits was investigated with clinic CT and fluorescence imaging. The results not only indicated the nanoemulsion could be served as a dual-modal contrast agent, but revealed it could specifically target to macrophages and visualize atherosclerotic plaques.