Preparation Of One-Dimensional Magnetic Nano Carriers And Their Cytotoxicity Investigation

Nanomaterials have gained wide attentions in biomedical field as the rapid development of nanotechnology. As the size of the nanomaterials is equal with the size of DNA, proteins and other biological macromolecules and virus, the biological effects of nanomaterials may be related to the interaction mechanism of biology and environmental which has been not fully understood yet. It is not only can greatly promote the development of nano-science in the biomedical field but can also provide a theoretical basis for a comprehensive understanding of the impact of nanomaterials on the environment and health of human survival to study on the interaction of nanomaterials with biological systems thoroughly and systematically. The biological effects of nano-materials are influenced by the size, morphology, surface charge, composition and selected types of cell models. This thesis focuses on one-dimensional magnetic nanomaterials with large aspect ratio and carries investigations on the preparation of one-dimensional magnetic nanomaterials for drug delivery and their biological effects at the cellular level. Iron (Fe), cobalt (Co) and nickel (Ni) nanowires were prepared by a template-assisted electrochemical depositon method. And then Fe@mSiO2nanowires and Fe@PANI nanowires were further prepared by an in situ polymerization method and a sol-gel method repectively. All the products were characterized by using scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. Human hepatoma cells (BEL-7402cells), human cervical carcinoma cells (HeLa cells), human breast cancer cells (MDA-MB-231cells) and human lung cancer cells (A549cells) were selected as the research models to carry the cell experiments. The cytotoxicity of the above mentioned several kinds of nanomaterials were conducted by determining the membrane integrity, mitochondrial metabolic activity, the content of intracellular reactive oxygen species and cell apoptosis. Additionally, we had done some primary investigations on their application in drug delivery. This dissertation can be further categorized into the following parts: 1. Iron (Fe), cobalt (Co) and nickel (Ni) nanowires were prepared by AC electrochemical depositon method in a home-made anodic aluminum oxide (AAO) template. SEM and HRTEM observations showed that the nanowires had linear structure, smooth surface and uniform diameter (-40nm), very large aspect ratio (10-100) and good crystallinity. VSM analysis demonstrated that all the three kinds of metal nanowires exhibited ferromagnetic behavior. Human hepatoma cell line BEL-7402cells were chosen to study the effects of the components of the nanowires on their cytotoxicity by MTT assay and LDH assay, the results indicated that all the three kinds of nanowires showed a concentration-dependent cytoxicity and the order was Co>Ni>Fe. The cell survival rate was still about90%when the concentration of Fe nanowire up to200μg/mL. These results showed Fe nanowires had a good biocompatibility and thus could be utilized as potential biomaterials.2. Cytotoxicity and cellular uptake of Fe nanowires to human cervical cancer cell (HeLa cell) were studied in detail, including the cell morphology, cell growth, and cellular uptake. The experimental results showed that Fe nanowires had good biocompatibility. The cell viability, ROS generation and mitochondrial membrane potential of HeLa cells after co-incubation with Fe nanowires for72h had no significant change compared to that of the control cells. The cellular uptake of Fe nanowires was observed by using optical microscope, laser confocal microscope, live cell workstations and transmission electron microscope. The results showed that the internalized Fe nanowires localized mainly in the cytoplasm instead of endoplasmic reticulum, mitochondria and the nucleus and other organelles. Based on the experimental results, we proposed a model of the cellular uptake pathway of the nanowires that might be related to their length: Fe nanowires with larger size might penetrate through the membrane into the cell directly, while Fe nanowires with smaller size entered the cells possibly via a receptor-mediated endocytosis way.3. Fe@mSiO2nanowires with Fe nanowire as core and mesoporous silica as shell for targeted drug delivery were prepared through electrodeposition followed by a CTAB-template sol-gel process. SEM, TEM, small angle/wide-angle XRD characterization results showed that Fe@mSiO2nanowires had very regular core/ shell structure with the length in the1～2μm and diameter of about120nm and the thickness of the mosoporous silica was about40nm. Nitrogen adsorption/desorption analysis showed that Fe@mSiO2nanowires had a large surface area of329.41m2/g, which indicated that the success coating of the mesoporous silica layer on the surface of Fe nanowires increased their specific surface area greatly, and thus provided good capability for loading drug molecules. The in vitro drug loading experiments of anticancer drug (DOX) showed Fe@mSiO2nanowires had a high drug loading content (4%) and encapsulation efficiency (>72%). Furthermore, MDA-MB-231human breast cancer cell was selected to investigate the cyototoxicity of Fe@mSiO2nanowires. MTT results showed low cytotoxicity of the nanowires, which was concentration-dependent and the cell viability was still nearly80%while the concentration was as high as250μg/mL. Moreover, LDH assay demonstrated that the Fe@mSiO2nanowires had little influence on the integrity of the cell membrane.4. Fe@PANI nanowires with Fe nanowire as core and PANI as shell were prepared by in situ polymerization of aniline monomer on the surface of Fe nanowires. The products were characterized by using SEM, HRTEM, XRD, infrared (IR), and thermogravimetric analysis (TG), and the results confirmed that PANI were coated on the nanowires successfully with a content of about10%. It was found that the in situ coating of PANI improved the stability of Fe nanowires in aqueous solution greatly, which made it more suitable for biomedical applications. We conducted research on the cytotoxicity of such composite nanowires using A549cells, and the results showed that the cytotoxicity of Fe@PANI nanowires was concentration-dependent. The cell viability was still nearly80%while the concentration was as high as200μg/mL.