Facile one-pot preparation, surface functionalization, and toxicity assay of APTS-coated iron oxide nanoparticles

We report a facile approach to synthesizing 3-aminopropyltrimethoxysilane (APTS)-coated magnetic iron oxide (Fe(3)O(4)@APTS) nanoparticles (NPs) with tunable surface functional groups for potential biomedical applications. The Fe(3)O(4) NPs with a mean diameter of 6.5 nm were synthesized by a hydrothermal route in the presence of APTS. The formed amine-surfaced Fe(3)O(4)@APTS NPs were further chemically modified with acetic anhydride and succinic anhydride to generate neutral (Fe(3)O(4)@APTS⋅Ac) and negatively charged (Fe(3)O(4)@APTS⋅SAH) NPs. These differently functionalized NPs were extensively characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry analysis, zeta potential measurements, and T(2) relaxometry. The cytotoxicity of the particles was evaluated by in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric viability assay of cells along with microscopic observation of cell morphology. The hemocompatibility of the particles was assessed by in vitro hemolysis assay. We show that the hydrothermal approach enables an efficient modification of APTS onto the Fe(3)O(4) NP surfaces and the formed NPs with different surface charge polarities are water-dispersible and colloidally stable. The acetylated Fe(3)O(4)@APTS⋅Ac NPs displayed good biocompatibility and hemocompatibility in the concentration range of 0-100 µg ml(-1), while the pristine Fe(3)O(4)@APTS and Fe(3)O(4)@APTS⋅SAH particles started to display slight cytotoxicity at a concentration of 10 µg ml(-1). The findings from this study suggest that the Fe(3)O(4)@APTS NPs synthesized by the one-pot hydrothermal route can be surface modified for various potential biomedical applications.