Ultra-Small Superparamagnetic Iron Oxide Nanoparticles Made to Order

Abstract

A fast, efficient and green microwave-assisted synthesis of ultra-small, superparamagnetic iron oxide nanoparticles is reported. By controlling the temperature and heating mode of a polyol reduction using triethylene glycol (TREG) as a green, high-boiling solvent, ultra-small nanoparticles (2-4 nm) exhibiting robust superparamagnetic behavior were obtained. The sizes of the nanoparticles were determined by TEM and DLS measurements. Using a ligand exchange process, the TREG molecules on the surface of the smallest nanoparticles (2 nm) were successfully replaced with Alendronate, an anti-cancer drug molecule, effectively transforming the nanoparticles into a potential theranostic agent.