| Auxin is an important kind of phytohormone which is first found and widely distributed in plants. Auxins have many functions in agricultural production, including promoting or inhibiting plants growth, promoting the growth of plant roots and the formation of adventitious and lateral roots, preventing organs shedding, promoting assimilation distribution and so on. Since different concentrations of auxins have different effects on organisms, the detection of auxins is very important. The traditional detection techniques can not realize fast, high-throughput, real-time determination, and have poor repeatability, so it can not meet the requirement of auxins detection and research.With the development of technology, biosensors have been extensively applied in biotechnology, clinical diagnosis, environmental monitoring and food industry due to its high sensitivity, simple apparatus and easy operation. Biosensors are suitable for high throughput and real-time measurement with the advantage of low cost, miniaturization, compact structure, high specificity and high sensitivity. Therefore, the biosensor technology for auxin quantification has vast application prospect.In this paper, the construction methods of piezoelectric and amperometric immunosensors for 2,4-D determination were researched, and the build of fluorescence immunosensor for IAA detection was also discussed. The main research results of the thesis were as follow:(1) In this paper, a new method for quantification of 2,4-dichloro phenoxyacetic acid was reported. A novel piezoelectric immunosensor has been developed and applied for 2,4-D detection, Gold nanoparticles (GNP) have been employed as a'weight label'to secondary antibody to amplify the response signal. The signal of sensor has a good linear relationship with the 2,4-D concentrations in the range of 13.3-666.0 ng/mL. The linear equation is y=-282.3+266.9x with a correlation coefficient R of 0.9933. The detection limit is 13.0 ng/mL. The results show that the method revealed a simple and inexpensive configurationin detection of 2,4-D with high sensitivity. In addition, the sensor could be regenerated under very mild conditions simply by immersing the sensor in glycine buffer solution to desorb the bound antibody. It was found that the renewed sensor could be used for about 9 runs without obvious loss of sensitivity. This work also provided a promising alternative approach for immunoassay of other small molecules.(2) A novel amperometric immunosensor has been researched for the detection of 2,4-D by combining self-assembly and competitive immunoreaction technique. This method improved the detection sensitivity by using gold nanoparticle labeled goat anti-mouse IgG to enlarge the signal. ACV technique is used to detect 2,4-D. The results shows good linear relationship with the logarithm of contents of 2,4-D in the range of 0.5 ng/mL-2000 ng/mL.The linear equation is y= 0.15x+1.2, and the correlation coefficient R is 0.9409 with a detection limit at about 0.1 ng/mL. This method constructs a new type of sensor which has a high detection sensitivity of 2,4-D and provides a new approach for the detection of other small molecular materials.(3) In this work, by fluorescence resonance energy transfer technology, the fluorescence immunosensor for the detection of exogenous IAA was constructed. When the emission spectrum of streptavidin labeled QD605 overlap with absorption spectrum of biotin labeled deoxyribose nucleotides Cb, and the distance between the two fluorophores is within a few atoms, the energy transfer between donor and recipient can occur in a nonradiactive way. The standard curve of IAA concentration and energy transfer rate was finally determined by fluorescence spectrophotometer. This work provides a new approach for IAA detection. |
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