Investigation Of Ions Transfer Through The Ion Channels

The biological membrane is the cut-off point of the cellular organism and thenon-cellular organism, so the formation of biological membrane is very important tothe evolution of life. The biological membrane maintained the ordered of the variousparts in the cell, it is closely related to many important processes, such as theintracellular energy metabolism, the material exchanging with the exteral environment,the biosynthesis of proteins and other macromolecules, the dissemination ofinformation and so on. The movement of electric charge is the primary process of thelife and the basic characteristics of the biomembranes. The liquid/liquid interface isconsidered to be the simplest model of biomembrane. Recently, the process of chargetransfer (electron and ion) at the interface is one of the research hotspot inelectrochemistry and electroanalytcial chemistry. Among of the charge transfer, theion transfer is the simplest parts, it is a common physical and chemical processes,which is correlation with solvent extraction, phase transfer catalysis, electrodialysisand life science. Especially, the ion transfer at the biomembrane not only maintainnormal metabolic activity of living cells, but also have the relationship with nervousexcitability and conductivity, the regulatory functions of the central nervous system,heart beat, peristaltic smooth muscle, skeletal muscle contraction, hormone secretionand so on. Therefore, studying the process of ion transfer at the interface andestablishing the reasonable kinetics theory are better for us to understand the iontransfer mechanisms and reveal the mysteries of the life processes.In this paper, we combine the scanning electrochemical microscopy (SECM),which is proposed and developed by Bard et al at the late1980s, and themicroelectrode technique which can construct micro-liquid/liquid interface toinvestigate the transfer process about the metal ions at the bionic interface.This thesis is divided into four parts, including the following:1. A short review was given on the progress of the liquid/liquid interfaceelectrochemistry, introduced the liquid/liquid interface model and research method. Meanwhile, the fundamental theory and the application in the interface chemistryof facilitated ion transfer were elaborated clearly.2. The aluminum oxide template (AAO) is modified at the liquid/liquid interface tosimulate the ion channels. Dibenzo-18-crown-6(DB18C6) as the ionophore inorganic phase, potassium ion as reactant in aqueous phase, we observed thedynamic process of the ions through the ion channel and got a got a series ofthermodynamic and kinetic datas about K+transfer in channels by controlling thepore size of the AAO. In addition, we discovered that the reaction rate constanthas a close relationship with the pore size of the alumina template. These studieshelp us to better explore the ion transfer mechanism.3. We use the micro-drop method and scanning electrochemical microscopy to studythe accelerating ion transfer reaction at the interface. We successfully observedthe magnesium ion transfer at the interface, due to the potential window is greatlywidened when we use the ionic liquid as a supporting electrolyte. Meanwhile, wefound when the concentrations of potassium ion or magnesium ion in microtubeare much higher than the concentration of DB18C6, the current controled by thediffusion of DB18C6, also the corresponding kinetic and thermodynamicparameters obtained.4. A solid electrode modified by a thick organic liquid membrane (ionic liquid) hasbeen used to study the ion transfer voltammetric behavior. We successfullyimplemented the study about the strongly hydrophilic ion transfer by using themost common electrically active material (TCNQ) as molecular probe. Theadvantage of this method is that it is insensitive to the traditional potential window.In addition, the ionic liquid as the solvent in organic phase, which avoidintroducing the other toxic organic solvent. At the same time, the organic phase isno longer needed the supporting electrolyte.