Effects of Nanoparticle Size on Cellular Uptake and Liver MRI with Polyvinylpyrrolidone-Coated Iron Oxide Nanoparticles

The effect of nanoparticle size (30-120 nm) on magnetic resonance imaging (MRI) of hepatic lesions in vivo has been systematically examined using polyvinylpyrrolidone (PVP)-coated iron oxide nanopartides (PVP-10s). Such biocompatible PVP-10s with different sizes were synthesized by a simple one-pot pyrolysis method. These PVP-10s exhibited good crystallinity and high T-2 relaxivities, and the relaxivity increased with the size of the magnetic nanopartides. It was found that cellular uptake changed with both size and surface physiochemical properties, and that PVP-10-37 with a core size of 37 nm and hydrodynamic particle size of 100 nm exhibited higher cellular uptake rate and greater distribution than other PVP-10s and Feridex. We systematically investigated the effect of nanoparticle size on MRI of normal liver and hepatic lesions in vivo. The physical and chemical properties of the nanoparticles influenced their pharmacokinetic behavior, which ultimately determined their ability to accumulate in the liver. The contrast enhancement of PVP-10s within the liver was highly dependent on the overall size of the nanopartides, and the 100 nm PVP-10-37 nanopartides exhibited the greatest enhancement. These results will have implications in designing engineered nanoparticles that are optimized as MR contrast agents or for use in therapeutics.