Study On The Cytocompatibility Of Carbon Nanotubes And Its Application In Biomaterial And Cell-sensing

Since their discovery in 1991, carbon nanotubes (CNTs) have found great applications in many fields including chemistry, physics and material science, etc. due to their unique one-dimensional, nano tubular structure, unusual mechanical, electrical and electrochemical properties On the other hand, in vitro assays using cultured cells are of great significance for studying many aspects of cell biology and drug screening. The construction of cytocompatible interface plays a key role for the fabrication of cell-based biosensors, and could undoubtedly promote the development of tissue engineering. In this thesis, a series of studies were carried out based on carbon nanotube about its cytocompatibility and application in biomaterial and cell-sensing. Some valuable results were obtained. The main points of this thesis are summarized as follows:1. Multi-walled carbon nanotubes (MWNTs) were treated and purified with mixed acid, and the raw MWNTs and acid-treated MWNTs were characterized with FTIR. The acid-treated MWNTs were easily dispersed in water. Then the cytocompatibility of both raw MWNTs and acid-treated MWNTs on osteoblastic MG-63 cells were investigated with microscopy observation techniques and MTT experiment. It has been found that both of the MWNTs did not express obvious cytotoxicity.2. The surface modification of chitosan substrate to promote cell-chitosan interaction has great importance for extending the application of chitosan as a tissue engineering scaffold material. In this work, the direct adsorption of MWNTs on chitosan film was confirmed by quartz crystal microbalance (QCM) and scanning electron microscopy investigations. The growth behaviors of MG-63 osteoblastsic cells on pure chitosan and MWNTs-modified chitosan films were investigated with MTT assay, acridine orange (AO) staining method and morphology observation. It was found that the surface modification of chitosan with MWNTs can significantly improve the attachment, spreading and proliferation of the MG-63 cells. This provides a very simple but effective method to enhance the cell-biomaterial interaction on the chitosan substrate. The proposed MWNTs-modified chitosan substrate can also be applied to the fabrication of cell patterns, which is important for the development of cellular biosensor technology and tissue engineering applications.3. MWNTs were used for the surface modification of glassy carbon electrode (GCE) to construct a non-toxic interface for immobilization of MCF-7 cells (human breast cancer cell line). Fluorescence microscopy observation showed that the presence of MWNTs on GCE surface significantly enhanced the attachment of MCF-7 cells, and thus an electrochemical impedance cell sensor was constructed. The attachment of cells on MWNTs-GCE resulted in increase of charge-transfer resistance (Rct) between the redox probe of Fe(CN)₆^3-/4- in electrolyte solution and electrode surface. A linear relationship was found between Rct and the logarithmic value of cell concentration ranging from 104 to 106 cell·mL^-1 with a detection limit of 7.0×10³ cell·mL^-1. EIS technique was also successfully used to monitor the growth of MCF-7 cells and evaluate the cytotoxicity of anticancer drugs using cisplatin as a model. This work implies that MWNTs-modified electrode possessed potential application for the immobilization of cells and construction of cell-based biosensor for electrochemical investigation of cell adhesion, proliferation and apoptosis.