The Preparation Of Ion Selective Microelectrode And The Study On The Release Of Calcium Ions Of Aloe Cells Induced By Multi-walled Carbon Nantubes

Carbon Nanotubes,as a new of kind nano materials with unique structural, physical and chemical properties, are widely used in industrial, energy, environmental, biological and medical fields. Because of its’ widely applications, it is significant to evaluate its’ biological safety. Presently, many studies have shown that CNTs do have some toxic effects. Although the studies of the biological toxicity of CNTs have made certain achievements, further investigations on the mechanism are still needed. As is known to all that free calcium ion is an important messenger in living cell’s signal transduction process, thus studies on the effects of CNTs on the metabolism of Ca2+ ions is very necessary for a deep understanding of the mechanism of the nano-toxicity of CNTs.In this thesis, calcium ion-selective microelectrode was used to study the release of Ca2+ ions from aloe protoplast induced by multi-walled carbon nanotubes. The fabrication conditions of ion-selective microelectrodes, such as the drawing temperature, the silanization temperature and the usage amount of the silylating reagent, were optimized. The prepared electrode displayed Nernst response in the range of 10-5~10-1 mol/L, the response slope is better than 26.8 m V/dec at 18 oC with a detection limit of61.12 10 mol/L-′. The MWCNTs were purified before using. The Aloe protoplasts used in the experiments were extracted by enzymatic method, and were washed with Ca2+-free culture medium to lower the Ca2+ background to about 10-5mol/L. Then the Aloe protoplasts was cultured in Ca2+-free culture medium with different sizes and concentrations of MWCNTs, respectively. The concentrations of Ca2+ ions were recorded continuously. The results showed that compared with the controls, the release of Ca2+ ions from aloe cell protoplasts was obviously accelerated by the MWCNTs. In the range of 20~40 mg/L, the release speed of the Ca2+ ions increased with increasing MWCNTs concentrations. When the concentration reached 50 mg/L, the release speed showed a slight decrease. For different diameters of MWCNTs, at same concentrations, the acceleration effect of large diameters of MWCNTs(20-30 nm) is larger than that of the small diameters of MWCNTs(<8 nm).These results revealed the influence of MWCNTs on plant cell from a new aspect, it is helpful for a deep understanding of the nano-toxicity mechanism and a better evaluation of the nano-safety of MWCNTs.