Folic acid-conjugated iron oxide porous nanorods loaded with doxorubicin for targeted drug delivery

Iron oxide porous nanorods (IOPNR) with lengths ranging from 40 nm to 60 nm and pore diameters ranging from 5 nm to 10 nm were prepared, and further modified with NH2–PEG–FA (FA–PEG–IOPNR) for ligand targeting and modified with NH2–PEG–OCH3 (PEG–IOPNR) as a control. Instead of chemical bonding, doxorubicin (DOX), a low water solubility anticancer drug, was loaded in the pores of the modified IOPNR because of their porous structure and high porosity. The release of DOX in acidic PBS solution (pH 5.3) was faster than that in neutral (pH 7.4) solution. The analysis results from TEM, inductively coupled plasma emission spectroscopy, confocal laser scanning microscopy, and flow cytometry analyses indicated that the presence of FA on the surface of the nanorods increase the cellular uptake of nanorods in the case of HeLa cells, a folate receptor (FR)-positive cell line. In contrast, for COS 7 cells, a FR-negative cell line, FA ligand on the surface of the nanorods showed no effect on the cellular uptake. MTT assay indicated that the cytotoxicity of DOX loaded in FA–PEG–IOPNR to HeLa cells was higher than that of DOX in PEG–IOPNR. In the case of COS 7 cells, no significant difference between the cytotoxicity of DOX loaded in FA–PEG–IOPNR and PEG–IOPNR was found. These results suggested that FA–PEG–IOPNR had the potential for target delivery of chemotherapeutic into cancer cells.