The Investigation Of Cytotoxicity Of One-dimension Magnetic Metallic Nanowires

Nanomaterials have been wide used as the rapid development of nanotechnology. Vary new nanomaterials have been prepared and have been used in clothing, food industry, paints, electronics and other fields. Human exposure to nanomaterials is inevitable as nanomaterials become more widely used. However, the biological effect of nanomaterials was not fully clear. The health risks of nanomaterials have been focused. Nanomaterials also have performed advantages in biomedicine. For example drug nanocarrier, label and diagnostic. For medical purposes, toxicology of nanomaterial is a critical factor. Therefore, understanding the properties of nanoparticles and their effect on the body is crucial before clinical use can occur. Among the wide variety of nanomaterials designed so far, magnetic nanowires have received considerable attention in nanomedicine because of their outperformance in bionanotechnology. However the interaction between nanowires and cell has not yet clear. The adverse effect of magnetic nanowires should be evaluated. Further investigated the interaction of nanowires and cells can not only provide a theoretical basis but also promote the application of nanowires. This thesis focuses on one-dimensional magnetic metallic nanowires, including preparation of nanowires and cytotoxicity evaluation. Fe and Ni nanowires were prepared by a template-assisted electrochemical depositon method. Nanowires were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and so on. Human cervical carcinoma cells (HeLa cells), were chosed as the research models to investigate the cytotoxicity. The cytotoxicity of the nanowires was investigated by mitochondrial metabolic activity, the generation of intracellular reactive oxygen species and cell apoptosis. We try to illuminate the mechanism of cytotoxicity of nanowires. This work can be further divided into the following parts:1. Iron (Fe) and nickel (Ni) nanowires were prepared by electrochemical depositon method in a self-made anodic aluminum oxide (AAO) template. The morphology of nanowires was observed by SEM and TEM, and the result showed that the nanowires had linear structure. The surface of nanowires was smooth and the diameter was uniform (40nm). XRD demonstrated that nanowires have good crystallinity. HeLa cells were chosen to study the cytotoxicity of the nanowires. MTT assay indicated that the cytotoxicity of Ni nanowires was larger than Fe nanowires. We further analyse the cytotoxicity difference. XRD showed that the surface of Fe nanowires were oxidized, however the Ni nanowires were not. ROS detection indicated that Ni nanowires induced ROS generation significant, however Fe nanowires can not induce ROS generation. These result suggested oxidization of Fe nanowires inhabited ROS generation so cytotoxicity was lower than Ni nanowires.2. We further investigated the the mechanism of cytotoxicity of Ni nanowires. The data from the annexin V/PI staining indicated that the apoptotic cell populations were increased in a dose-dependent manner. The fluorescent images of cells stained with DAPI indicated that the chromosome condensation and formation of apoptotic bodies in the Ni NWs treated-HeLa cells. These results revealed that apoptosis is a major manner of Ni NWs inducing cell death. Cell cycle analysis indicated that cell cycle arrested in S phase, as well as Ni nanowires induced mitochondrial membrane potential disruption. our data demonstrated that Ni NWs induce apoptosis in HeLa cells through ROS generation and suggested that ROS induce HeLa cell apoptosis through mitochondrial damage or activating cell cycle checkpoints.