| There are many signal molecules in plant, which coolaborates and accommodates with each other for keeping natural vital movement of physiology and pathology in organism. Hydrogen peroxide owns strong oxidizability and toxicity in plants, it is necessary to keep Hydrogen peroxide in a normal range to prevent the healthy cell being killed. Similarly, as a signaling molecule, except for regulating the vital movement of plant, nitric oxide possesses the reducibility, but NO with high concentration in organism could poison the healthy cells. These signal molecules participate in the physiological process such as biotic and antibiotic stress, in that case, detecting these signal molecules in vivo is a great stimulative for researching the vital phenomena.It is a continuous process of signaling molecule change in plants. Because of convenient and simple operation, micromation of electrode, no requirement of tracer element and costing low, electrochemical biosensor is proper method to measure these small molecules continuously in vivo.In this paper, electrochemical modification of microsensor was employed to get the H2O2 sensor and NO sensor, which were applied to measured H2O2 and NO respectively in vivo. Main study content contains three parts as follows:(1)In order to gain H2O2 sensor, after Pt particulate scattered on the Pt working electrode, the polymer of o-phenylenedianime (o-PD) was electrodeposited on the Pt/Pt electrode. H2O2 sensor possesses good electrochemical capability, and cathodic current was measured at the potential of -0.1V, there is a good linear correlation between the cathodic current and concentration of H2O2 (R=0.995) with detection limit of 25μmol/L. H2O2 in oilseed rape induced by salicylic acid was detected on the Pt/Pt/POPD electrode in vivo successfully. The result of this study indicates that there are two oxide burst (OB) in oilseed rape when salicylic acid infect the plant. Besides, the intensification and duration of oxide burst of the second time is more than the first time. And generated H2O2 in different parts of plants were also tested, it is known that the OB for the first time is to stop the continuing spread of virus, and OB for the second time is the response of the defense of the whole plant. (2)?o-phenylenediamine (OPD) and Nafion is covered on the Graphite electrode after modified by electrodepositing a thin membrane of Nickel phthalocyanine (NiTSPc), which gains obvious anodic current when potential is +0.8V, and there is a good linear correlation between the anodic current and concentration of NO (R=0.995). Meanwhile GE/NiTSPc/POPD/Nafion electrode displays a good sensitivity and selectivity against the interferer of ascorbic acid (AA), nitrite (NaNO2) and peroxide (H2O2) from nitric oxide. Furthermore, NO induced by ultraviolet radiation in tobacco is detected successfully in vivo. As the result, lever of NO will increase twice when there is UV-C radiation stress.?(3) A new style integrated microelectrode was provided to application in vivo better. An insulating Pt wire (diameter 0.1mm) and a silver wire were inserted into a capillary and fixed with Epoxy, and silver wire was eroded with nitric acid to the cupped shape. This kind of integrated microelectrode possesses good electrochemical capability and repeatability with average potential 0.11V and standard deviation 0.0032. Then, as the method mentioned in chapter 2, the integrated microelectrode was decorated to H2O2 sensor, and it was employed to test the H2O2 in oilseed rape in vivo prosperously. From the result, it was seen there was only one time of OB. Because the area of working electrode is very tiny, and the current signal of first OB is weak in addition. The first current signal on the working electrode is covered by noise. |
PDF Full Text Request