Based On Silica Nano-cavity Array Electrode For Electrochemical Study And Application

From biological systems to various artificial materials,nano-pores or nano-channels are ubiquitous.Mesoporous silica materials have attracted great interest because of their special structures such as high specific surface area,uniform pore distribution and adjustable pore size.In particular,the vertically oriented nano-channels of the mesoporous silica material are beneficial to the migration of substances to the substrate and have a wide range of applications in analytical science.Due to the various interactions between ions or molecules and silica nano-channels,many functions,such as selectivity,permeability and so on,can be realized by using size limitation and tailoring the interior components,From this point of view,according to the summarized critical principles of the size/shape,charge,recognition and other interactions in the transport process of ions and molecules in silica nano-channels,this paper introduces three main application areas:simulating biomembrane to study the ion transfer process on cell membrane,quantitatively evaluating the selective permeability of molecules in the nano-channels by scanning electrochemical microscope?SECM?,and constructing sensors to detect drug molecules quickly and sensitively.Therefore,understanding the"structure-performance"relationship is of great significance for developing high performance analysis methods and understanding life phenomena based on mesoporous silica materials.This paper mainly includes the following four parts:1.The paper briefly describes the different dimensions of artificial nano-pores and nano-channels,mainly introduces the advantages of silica nano-channels system in structure and performance,involving the key principles of size effect,shape effect,charge effect and hydrophilic/hydrophobic effect,which can be successfully applied to various systems,such as the construction of liquid/liquid interface to simulate biofilm,selective transport of ions and molecules,single molecule electrochemistry,high sensitivity detection,etc.2.In this chapter,silica nano-cavity array electrodes?SNCA/ITO?with different thicknesses were successfully prepared by using the growth method of St?ber solution and controlling the constant temperature heating time,and the thickness is controlled between 70 and 120 nm.Then a new type of liquid/liquid?L/L?interface array is constructed by using the nano-cavity array electrode to simulate biofilm and carry out cross-phase research on it.Due to the special charge properties on the surface of the nano-cavity,it has better selectivity and regulation to ions with lower electronegativity.The small and uniform nano-cavity diameter?2-3 nm?makes it have obvious confinement effect,which is more conducive to the adjustment of ion transfer.The scanning electrochemical microscope?SECM?technology was further applied to reveal the ion transfer mechanism at the interface,providing a good platform for studying ion transfer in biofilm.3.In this chapter,two kinds of silica nano-cavity with two different surface charges,namely negatively charged silica nano-cavity arrays?SNCA?and positively charged amino-functionalized SNCA?ASNCA?,were prepared by a convenient,cheap and simple method.Three redox probe molecules with different charges are selected:Fe?CN?₆^3-,FcCH₂OH and Ru?NH₃?₆³⁺,of which Fe?CN?₆^3-is negatively charged,FcCH₂OH is neutral and Ru?NH₃?₆³⁺is positively charged.The diffusion energy and diffusion rate constants of the three redox probe molecules in nano-cavity with different charges are studied by using SECM technology in a four-electrode system.The experimental results show that the diffusion rate constants of Ru?NH₃?₆³⁺,FcCH₂OH and Fe?CN?₆^3-on SNCA/ITO electrode are decreasing,while on ASNCA/ITO electrode are increasing.4.This chapter adopts a three-electrode system,in which the silica nano-cavity arrays electrode?SNCA/ITO?is used as the working electrode,the Ag/AgCl electrode is used as the reference electrode,and the Pt electrode is used as the counter electrode.Based on the selective permeability of the silica nano-cavity,the cationic?-blocker propranolol hydrochloride drug molecules are rapidly,sensitively and selectively detected,and the lower detection limit?LOD=0.76±0.01?m?and wider dynamic concentration range?0–400?m?were obtained.The sensor is also compatible with on-site detection and real-time detection,and has broad application prospects in many fields such as sensing,molecular separation and so on.