Biocompatibility, MR imaging and targeted drug delivery of a rattle-type magnetic mesoporous silica nanosphere system conjugated with PEG and cancer-cell-specific ligands

Rattle-type magnetic mesoporous silica nanospheres (RMMSNs) with a magnetic core and a mesoporous silica shell were prepared, and then the surface properties of the nanospheres were modified with biocompatible polymer poly(ethylene glycol) (PEG) and cancer-cell-specific ligand folic acid (FA), with the aim of specifically targeting cancer cells. Combined Prussian blue staining, magnetic resonance imaging, and high-resolution sector field inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis revealed that the obtained RMMSN-PEG/FA nanocomposite can specifically target cancer cells over-expressing FA receptors (FRs). The nanocomposites displayed very low in vitro toxicity and negligible hemolytic activity, which is in favor of further biological applications. Water-insoluble anticancer drug docetaxel was loaded into the surface-modified RMMSNs and delivered into human cancer cells via cell uptake. Surface conjugation with cancer-specific targeting agent FA increased the uptake into cancer cells that over-express FRs. In addition, after intravenous injection, the RMMSN-PEG/FA nanocomposite could be transported to the designated organs under an external magnetic field. Findings from this study suggest that the RMMSN-PEG/FA could be used as a platform for simultaneous imaging and therapeutic applications.