Study on the endocytosis and the internalization mechanism of aminosilane-coated Fe₃O₄ nanoparticles in vitro

Abstract

In this study, the endocytosis and the internalization mechanism of aminosilane-coated Fe₃O₄ nanoparticles into human lung cancer cell line SPC-A1 was studied compared with human lung cell line WI-38 in vitro. The particle endocytosis behavior was studied by using Transmission Electron Microscope (TEM) and Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). It was found that aminosilane-coated Fe₃O₄ nanoparticles could be greatly taken up by SPC-A1 human cancer cells (202 pg iron/cell) but not by WI-38 human lung cells (13 pg iron/cell). The particles could be retained in SPC-A1 cells over a number of generations in vitro. Different endocytosis was observed by TEM after SPC-A1 cells were treated with different temperature or with/without Cytochalasin B (Inhibitor of phagocytosis) at 37 °C. No nanoparticles were taken up by SPC-A1 after the endocytosis inhibited in low temperature. Restoring the endocytosis activity at 37 °C, the process of nanoparticles from coated pit to endosomes and lysosomes was observed by TEM. Endocytosis activity was effectively inhibited by the presence of Cytochalasin B at 37 °C, while a lot of nanoparticles were uptaken to the cytoplasm of SPC-A1 cells in the control group. Our results suggest that the process of endocytosis of aminosilane-coated Fe₃O₄ nanoparticles can efficiently takes place in lung cancer cells and nanoparticles can be kept in cancer cells for generations. Phagocytosis may be involved in the internalization process of aminosilane-coated Fe₃O₄ nanoparticles.