Electrochemical Determination Of Plant Hormones On Three Dimensional Network Graphene-Based Nanomaterial Modified Electrode

Indole-3-acetic acid?IAA?and salicylic acid?SA?are important hormones produced by plants and involved in various physiological activities in plants.They are related to the whole process of plant growth and development.Therefore,it is crucial to detect a variety of plant hormones at the same time.The electrochemical sensing method is fast,sensitive and easy to operate,and has received extensive attention in recent years.In this paper,IAA and SA were used as the detection objects,and two kinds of sensitive electrochemical sensing platform with selectivity,easy operation,good stability and high repeatability were constructed using gold nanoparticles doped graphene hydrogel?AuNPs-GH?as modified electrode materials.This experiment realized the detection of IAA and SA,and the specific research contents are as follows:1.An electrochemical sensor was constructed based on GH nanomaterial modified electrode.The mixed solution containing graphene oxide?GO?and sodium ascorbate was reacted in autoclave at 90°C for 3 h,and it obtained GH power after freeze-dried.The GH electrochemical sensor?GH/GCE?is prepared for simultaneous detection of IAA and SA.The electrocatalytic behavior of IAA and SA on the surface of modified electrodes was investigated by cyclic voltammetry?CV?and linear sweep voltammetry?LSV?.The results show that the oxidation of IAA?0.78 V vs.Ag/AgCl?and SA?1.0 V vs.Ag/AgCl?occurs at different potentials,which allows GH/GCE to simultaneously detect IAA and SA.Under optimal conditions,the linear response of GH/GCE to IAA and SA ranges from 4²00?M,and the detection limits?S/N=3?are 1.42?M?IAA?and 2.80?M?SA?.The sensor has good selectivity and stability.It was used for the detection of IAA and SA in vegetable samples with satisfactory results.2.An electrochemical sensor was constructed based on gold nanoparticles doped GH nanocomposite modified electrode.The mixed solution containing graphene oxide?GO?,chloroauric acid?HAuCl₄?and triethylenetetramine?TETA?was reacted in autoclave at 180°C for 12 h,and it obtained AuNPs-GH power after freeze-dried.The AuNPs-GH/GCE electrochemical sensor which can be used for simultaneous detection of IAA and SA was successfully constructed.The prepared composite AuNPs-GH has a larger specific surface area and catalytic properties than a single GH or AuNPs.This chapter optimizes the oxidation potential,content of gold nanoparticle,hydrothermal reaction temperature and other conditions of IAA?0.8 V vs.Ag/AgCl?and SA?1.25 V vs.Ag/AgCl?,and uses current-time method?i-t?for simultaneously detected IAA and SA.Under optimal conditions,AuNPs-GH/GCE showed a linear relationship with IAA in the range of 0.8⁴ and 4¹28?M,and a linear relationship with SA in the range of 0.8⁸.4?M and 8.4¹88.4?M.The limit of detection?S/N=3?was 0.21?M for IAA and 0.22?M for SA.The sensor has good sensitivity and stability.The results were satisfactory by testing the IAA and SA and the spiked recovery experiments in the actual samples.