Enhanced cellular uptake of silica-coated magnetite nanoparticles compared with PEG-coated ones in stem cells

Monodispersed magnetite (Fe₃O₄) nanoparticles (NPs) were prepared through the thermal decomposition method. The obtained NPs were surface modified with silica (SiO₂) and polyethylene glycol (PEG), to enhance their stability in aqueous environment and their cellular uptake efficiency for biomedical applications. The NPs were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR) spectroscopy, and dynamic light scattering (DLS). The cytotoxicity of these NPs on bone marrow mesenchymal stem cells (BM-MSCs) was measured by MTT assay (cell viability test) at various concentrations (2, 5, 12.5, 25, and 50 μg/mL). The cells remained more than 90% viable at concentrations as high as 50 μg/mL. To compare the cellular uptake efficiency, these NPs were treated in BM-MSCs and the Fe concentration within the cells was measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. The uptake process displayed a time- and dose-dependency. The uptake amount of SiO₂-coated Fe₃O₄ (Fe₃O₄@SiO₂) NPs was about 10 times higher than that of the PEG-coated ones (Fe₃O₄@PEG).