Self-Assembly Of Size-Controllable Nanopores On The End Of A Glass Nanopipette:Fabrication,Electrochemical And Spectral Characterization

Channel and pore structures with size smaller than 100 nm at least in one dimension are usually termed as nanopores.Within the nanochannels/nanopores,the interactions between molecules or ions and channel wall become significant,which makes the nanochannels/nanopores have unique properties of mass transport as compared to the macroscopic systems.Due to these characters,nanochannels/nanopores have been extensively used in the research fields of DNA sequencing,single molecule analysis,bionic smart sensors,intelligent controlled drug delivery and separation and detection of biological substances.To explore the fundamentals of unique mass transport,single nanopore shows various advantages over multichannel structure.Glass/quartz capillaries are widely used to fabricate nanopores because they are easy to be fabricated.It has been shown that nanopores larger than 50 nm can be easily and repeatedly fabricated using laser-based capillary puller.However,This pulling technique is not suitable for preparing nanopores with aperture smaller than 50 nm,especially difficult for preparing nanopores smaller than 10 nm.To solve the problem,we proposed a new method of preparing porous nanostructures with pore size smaller than 10 nm by self-assembling gold nanoparticles around the tip of a glass capillary with ca.100 nm aperture in this thesis.The electrochemical rectification and the surface enhanced Raman scattering effect of the formed porous Au nanostructure were studied.This Master Degree thesis contains four chapters:The first chapter summarizes the progresses made in the area of nanopores,self-assembly and surface enhanced Raman scattering.At the end of this chapter,the motivation and goals of this thesis are proposed.The second chapter describes the method of nanoparticles self-assembly at a glass capillary tip by using dual-mercator compounds as the cross linkers.1,3-Propanedithiol,1,6-ethanthiol,1,9-nonanedithiol were used as the crosslink reagents to manipulate precisely the nanochannel size.The influence of self-assembly time on the size of the formed nanoporous structure was discussed.In the third chapter,the electrochemical properties of the formed nanoporous structure were studied.With 1,9-nonanedithiol(1.34 nm),1,6-hexamethylene thiol(0.95 nm),1,3-propanedithiol(0.58 nm)as the crosslink reagents in the assembly of nanochannels,the correlation between the size of nanochannel and ionic rectification was studied.In the fourth chapter,the surface enhanced Raman scattering effect of the formed porous nanostructures was studied.High sensitive detection of glutathione,explosive DNT and metal ions(Fe3 +,Pb2+,Zn2 +,Cu2+,Ni2+)has been realized by using the self-assembled gold-sphere as the surface-enhanced Raman scattering substance.