Study On The Electrochemical Behavior Of Living Cells And Cytocompatible Biomaterials

Cells as the basic units of the life, are very necessary for the developmental and physiological process of the organism. The metabolism, respiration, photosynthesis, message communication and substance transportation between membranes of living cells are all related to electron or electroactive species transfering in order and specific manner. Moreover, electrochemical technique is very simple, rapid and cheap. Therefore, it can be easily used to study many aspects of cell biology and drug screening. On the other hand, the construction of cytocompatible biomaterials is of great significance for promoting the development of tissue engineering. The main work of this thesis, which is based on the analysis mentioned above, is summarized as follows:1. The electrochemical behavior of human breast cancer cell (MCF-7) suspension on multi-walled carbon nanotube (MWCNT) modified graphite electrode was studied by using cyclic voltammetry (CV) and potentiometric stripping analysis (PSA). Compared with bare graphite electrode, the MWCNTs-modified electrode shows electrocatalytic property to the oxidation of electroactive species in the cell suspension. Ultrasonication treatment of the cell suspension can significantly enhance the PSA signal. The baseline-corrected PSA signal is found to be related to the viability of cells and the technique was used for monitoring the growth of MCF-7 cells. The effect of anti-cancer drug 5-fluorouracil (5-FU) on the growth of MCF-7 cells was also investigated by PSA.2. Electrochemical impedance spectroscopy (EIS) was used to monitor the growth of MCF-7 cells in real time and evaluate the cytotoxicity of chemicals using Fe(CN)₆^3-/4- as a redox probe. Tiny indium tin oxide (ITO) glass slides were used as the working electrode and cell culture substrate. The transparent property of ITO facilitates the morphological observation of cells during the culture course. Fluorescence microscope images were also used to observe the effects of the two antitumor drugs on the morphology of the cells. General consistency has been found between the EIS response and the morphological observation. Such an impedance method provides a simple, inexpensive but effective way for in vitro drug screening. 3. MWCNTs were used to reinforce the mechanic strength of chitosan. Pt nanoparticles were self-assembled on chitosan/MWCNTs film, and human osteoblast-like MG-63 cells were cultured on the composite film. It is found that the assembly of Pt nanoparticles on chitosan/MWCNTs film significantly enhances the attachment, spreading and prolonged the proliferation period of human osteoblast-like MG-63 cells. Effect of self-assembly time on cell morphology was also studied. This study will promote the application of chitosan in tissue engineering.