Decreased reticuloendothelial system clearance and increased blood half-life and immune cell labeling for nano- and micron-sized superparamagnetic iron-oxide particles upon pre-treatment with Intralipid

► Intralipid targets the liver Kupffer cells and blunts nanoparticle clearance. ► Intralipid results in an ~ 50% decrease in liver uptake of USPIO and MPIO particles. ► Intralipid produces an ~ 3-fold increase in blood half-life of the particles. ► Intralipid causes a 2 to 5-fold increase in labeling efficiency of blood monocytes. ► Nanoparticles can target more diverse sites or organs, other than the liver.