| Phytohormones play a key role in the whole growth of plants and have long been a hot topic in the field of agronomy and biology, and results of their study have made great contribution to the progress of agricultural science and technology. Moreover, phytohormones play an irreplaceable role in pushing the green revolution, increasing the crop yield, and ensuring national food security. However, owing to a series of factors including phytohormones existing in trace level, the uneven distribution in time and space and the complicated composition in the plants, the determination of phytohormones was greatly limited. The traditional methods such as chromatography, spectrometry and capillary electrophoresis existed many defects, which could not meet the requirements of scientific research analysis, while electrochemical method has been proposed as efficient alternative for the determination of phytohormones due to its advantages of time-saving, low-cost, simple operation, sensitivity, selectivity, miniaturization, and real-time online detection. There have been some electrochemical sensors fabricated by the researchers, and building the high performance sensor that can detect the phytohormones has become one of the hot research topics. In our work, the carbon nanobute materials, nanoclay materials and its composites were selected to make the electrochemical sensors that could successfully determine the phytohormones. In addition, its properties, such as stability, selectivity, sensitivity and practicability have been investigated, and the reaction mechanism of some phytohormones has been carefully studied. The specific content is as follows:(1) By combining the merit of montmorillonite(MMT) with high effective surface area and surface adsorption capacity and single walled carbon nanotube(SWCNT) with excellent electrocatalytic ability, and dispersing them in the solution of carboxymethyl cellulose(CMC), the CMC-SWCNT-MMT/GCE was successfully fabricated that can detect the trace indole-3-acetic acid(IAA) and salicylic acid(SA). The as-prepared CMC-SWCNT-MMT/GCE exhibited high sensitivity, low detection limit, good sensor performance and so on, which provided a possibility that can determine the IAA and SA in real samples.(2) Herein, an interesting electrochemical phenomenon on voltammetric behaviors for the electrochemical oxidation of 6-benzylaminopurine(6-BAP) which was one of the well-known phytohormones under the different pH conditions was investigated, and the content of 6-BAP in real samples was detected by the adsorptive stripping voltammetry using MWCNT/GCE. The pH-controlled voltammetric behaviors like peak potentials, peak currents, peak shapes and peak number of 6-BAP were discussed by the protonation-dissociation equilibria of 6-BAP in combination with electrocatalytic oxidation mechanism of 6-BAP. The electrochemical sensing performance such as the linear range, limit of detection(LOD), limit of quantification(LOQ), sensitivity, selectivity, precision and applicability for the pH-controlled stripping voltammetric detection of 6-BAP was also evaluated. Finally, it was concluded that the adsorptive stripping voltammetric determination of 6-BAP content with real samples in acid solution was more feasible and applicable.(3) By combining the virtue of halloysite nanotubes(HNTs) with good property of immobilizing the biologically active molecules and multi-walled carbon nanotube(MWCNT) with excellent electrocatalytic ability, and dispersing them together in the water, HNTs-MWCNT /GCE was successfully fabricated that can detect the artificially synthesized phytohormones as maleic hydrazide(MH) and kinetin(KT). In addition, the modified electrode displayed excellent reproducibility, sensitivity and selectivity during detecting the MH and KT, and was successfully employed to detect the content of MH and KT in lettuce. Moreover, this proposed electrochemical sensor provided a promising candidate for the trace analysis of MH and KT in agricultural crops. |
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