Single-Molecule Electrochemiluminescence Microscopy

Investigating the single-molecule reaction process is helpful in eliminating ensemble average effects,verifying chemical theories at molecular level,and is also a necessary means for single-molecule fluorescence probe imaging,high-sensitivity chemical sensing,and photovoltaic/electrocatalytic research.The current signal obtained from electrochemical measurements can directly reflect the electron transfer process in the electrochemical process.However,the direct measurement method for single-electron transfer processes of single molecules in solution is still very limited.Therefore,developing advanced single-molecule electrochemical measurement techniques to detect single-electron transfer processes in single-molecule reaction processes will help deepen the understanding of the electrochemical reaction mechanism at the single-molecule level.Based on this,in Chapter 1,this thesis firstly discussed the commonly used techniques for single-molecule chemical measurement.Due to the property that electrochemiluminescence can convert the signal of single-electron transfer into the easy detected single-photon signal,electrochemiluminescence could be the potential technic in single molecule electrochemistry imaing.A brief introduction of he development of electrochemiluminescence and its scientific challenges: 1)achieving single-molecule detection and 2)achieving super-resolution imaging are also briefly described in this chapter.Finally,this chapter introduces the basic concepts and common methodologies of super-resolution imaging.And it summarizes based on the concept of the single-molecule localization microscopy,super-resolution electrochemiluminescence imaging can be achieved by detecting-localizingreconstructing the single-molecule electrochemiluminescence signal.Based on the above two challenges of electrochemiluminescence,in Chapter 2,this thesis constructed a single-photon imaging microscope with advanced photodetectors and reasonable design of optical system.The signal of the ECL process at the single-molecule level was successfully detected by using the " spatial-temporal isolation " strategy,and its statistical and kinetic characteristics were also analyzed.In Chapter 3,by combining the concept of single-molecule localization microscopy to locate and reconstruct the detected single molecule electrochemiluminescence signals,the imaging resolution was improved from the submicronmeters to 22 nanometers.This achieved super-resolution ECL imaging,namely single-molecule electrochemiluminescence microscopy.Based on the potential live cell-friendly properties of electrochemiluminescence,the author applied singlemolecule electrochemiluminescence microscopy to high spatiotemporal observation of cell adhesion movement in live cells,making it a complementary imaging technique to fluorescence imaging.In Chapter 4,based on the detection sensitivity of single-molecule reaction events and single-electron transfer events of single-molecule electrochemiluminescence microscopy,the "electro-photon conversion" strategy was applied to achieve imaging of catalytic sites by single-molecule electrochemiluminescence microscopy.The measurement of thermodynamic and kinetic parameters with high spatial-temporal resolution was futher achieved.In Chapter 5,the author summarized the work of this thesis and proposed the issues that need to be addressed in the future development of single-molecule electrochemiluminescence microscopy.The author also looked forward to its potential applications.The author believes that in the future,single-molecule electrochemiluminescence super-resolution microscopy will help better illustrate its unique chemical dimension imaging of electrochemiluminescence.This may promote the progress of electrochemiluminescence research,in vitro immunodiagnosis,cell imaging,catalyst design,and electrochemical measurement methodology.