Intracellular uptake of folate receptor targeted superparamagnetic nanoparticles for enhanced tumor detection by MRI

Folic acid (FA) was conjugated to superparamagnetic iron oxide nanoparticles to develop a tumor specific contrast agent for magnetic resonance imaging (MRI). In this scheme a bifunctional poly(ethylene glycol) (PEG) linker was utilized to both increase biocompatibility and reduce nanoparticle agglomeration. The uptake of nanoparticle-PEG-FA conjugates by folate-receptor (FR) positive MCF-7 cells was compared against that of nanoparticles coated with only PEG over a range cell incubation times. Significant intracellular uptake was observed for MCF-7 cells cultured with nanoparticle-PEGFA conjugates compared to those incubated with nonspecific control nanoparticles. In addition, the preferential uptake of nanoparticle-PEG-FA conjugates by MCF-7 cells, as compared to FR-negative HT1080 cells, was observed through MRI. These results suggest that the synthesized FA superparamagnetic nanoparticle conjugates can potentially be used to target specific tumor cells for detection by MRI.