Investigation Of Ions Transfer Through The Ion Channels By Scanning Electrochemical Microscope

The liquid/liquid (L/L) interface has been considered as the simplest model forbiological membranes. Charge transfer (electron transfer and ion transport) at L/Linterface is the central themes of the study on the L/L interface. Among of the chargetransfer, the ion transport is the simplest parts. It is a common chemical and physicalprocesses, which is correlation with phase transfer catalysis, solvent extraction,chemical sensor, electrodialysis, solar energy conversion and life science. Particularly,the ion transport at the L/L interface plays an important role in cell physiologyregulation of many critical cellular functions and a large variety of life processes.Consequently, studying the process of ion transport at the interface is important for usto understand physiological process and reveal the mechanisms of ion transport andthe mysteries of the life processes.This thesis gives an overview of the development history and the fundamentalelectrochemic theory of the liquid/liquid interface. The micro-drop method, scanningelectrochemical microscopy (SECM) and the micro-tube technology are applied toinvestigate the ion transport across interface in the thesis.There are four parts in this thesis, and the main contents are as follows:1. A short review was given on the progress of the liquid/liquid interface.Weintroduced the liquid/liquid interface model and research method. Meanwhile, thefundamental theory and the application in the interface chemistry of ion transportwere elaborated.2. In this chapter, the simple hydrophilic alumina nanochannel is constructed atliquid/liquid (L/L) interface to simulate veritably and compactly complexcross-channel ion transfer processes of living systems in a similar physiologicalsaline environment. This channel shows good selectivity for ions with lowelectronegativity due to a difference in electrostatic interaction between theelectric field and different ions. Surface charges of nanochannel was governed byadjusting ionic strength of the electrolyte and pH of the aqueous phase. Theregulatory role of ion channel in confined space was achieved by varying diameter of alumina nanochannel and lengths of ions travel path. In addition, a new theorybased on the Randles-Sevcik equation is proposed for evaluation of cross-channelion transfer for the first time.3. In this part, we have successfully constructed H+-responsive ion channels byfunctionalization of the interior surface of the nanochannels with3-aminopropyltrimethoxysilane. This design strategy could take advantage of thedifferences of the protonization of amino group at different solution pHs to changethe surface charges and further modulate the transportation of ion in confinedconditions.4. A solid electrode, which is modified by a thick ionic liquid membrane, has beenused to study the ion transport voltammetric behavior. Here, We successfully usedthe most common electroactive species (Fc) as molecular probe to implemente thestudy about the transfer of strong hydrophilic anion. This method is insensitive tothe traditional potential window. Moreover, the ionic liquid can serve as thesupporting electrolyte. Meanwhile, it can avoid introducing the other toxic organicsolvent.