Functionalization of iron oxide nanoparticles with a versatile epoxy amine linker.

A synthetically diverse linker molecule consisting of both a terminal epoxide and a terminal amine has been synthesized and shown to have the desired reactivity. Proof of principle experimentation showed that the prepared linker molecule possessed the ability to be reactive towards dextran coated iron nanoparticles, essentially converting the surface alcohols to amines with an efficiency on average of 50 linkers per nanoparticle. Once the surface of the nanoparticles had been functionalized, the iron nanoparticles were subsequently functionalized with both folic acid and fluorescein isothiocyanate, with an average efficiency of 20 and 3 molecules per nanoparticle, respectively. The labeled nanoparticles were then incubated with both folate receptor positive and negative cell lines, which showed a preferential accumulation of the particles in the receptor positive cell line. In addition to the fluorescence based assays, accumulation of the nanoparticles was demonstrated using T2-weighted MRI imaging, which showed that the iron core of the nanoparticle was present within the desired cell line. Overall, this linker has shown the ability to functionalize the surface of nanoparticles and can theoretically be used to label a wide variety of other targeting agents or imaging agents for in vivo therapies or diagnostics.