Electrochemical Study On Small Bioactive Molecular In Plant Tissues

Plants are a major group of life forms. About 350,000 species of plants, defined as algae, seed plants, bryophytes, ferns and fern allies, are estimated to exist currently. There are many types of bioactive substance, such as acids (include vanillic acid, cinnamic acid, acetic acid, indole-3-acetic acid, hydrogen cyanide etc.), alkalis (include quinine, berberine, adenine, guanine, etc.), quinones (include juglone, chlortetracycline, etc.), terpenes, steroids, aldehydes, ketones, porphyrin and many others. Many medicine acquired from plants'roots, sterns, flowers, barks, leafs and fruits are of high pertinence and low poisonous and side effects, therefore is a major source of clinical medicine. For example, ginkgetin is extracted from ginkgo biloba, ephedrine from herba ephedrae, kavalactone from piper methysticum forst, strychnine from nux vomica, quinidine from cinchona, etc. Therefore, the research for the bioactive substance in plant tissues is of great importance.As a fast, convenient, high sensitive and selective way, electrochemical method can be used in researches of the process of electron transfer in bioactive substance, determine the basic thermodynamics and kinetics parameters, reveal the mechanism of electron transfer in organism. Therefore electrochemical method is widely used to study bioactive substance in plant tissues. Carbon nanotubes'high performance suggests that they have the wide application foreground in biomedical engineering. Using carbon nanotubes in the study of bioactive substance in plant tissues is of great importance to reveal the mechanism of electron transfer, energy conversion and metabolism in plant tissues and discover the relationship between the physical and chemical properties and the function of bioactive substance in plant tissues. Also, carbon nanotubes can further improve the sensitivity of the electrochemical method.In this paper, multi-wall carbon nanotubes modified glassy carbon electrode (MWNTs/GCE) was prepared and used to study the electrochemical behavior of indole-3-acetic acid (an important kind of endogenous plant hormone in plant tissues) and emodin (a type of bioactive substance in plant tissues). It was found that multi-wall carbon nanotubes could better catalyze the electrochemical behavior of both indole-3-acetic acid and emodin. Compared to glassy carbon electrode (GCE), MWNTs/GCE was not passivated and preserved good activity after studying the electrochemical behavior of indole-3-acetic acid. Emodin presented better electrochemistry behavior at MWNTs/GCE. The electrocatalytic redox process was a two-charge-two-proton process. Diffusion coefficient was obtained. The peak currents of the irreversible oxidative peak increased linearly with the concentration of emodin. The result of the detection of emodin by this electrochemical method matched that obtained by UV-visible spectrometry. Therefore, the determination using MWNTs/GCE was accurate and reliable. Thus a novel possible way for the detection of emodin is provided.