Electrochemiluminescence Imaging Analysis At Single-particle Level

Electrochemiluminescence(ECL)is a kind of luminescence phenomenon caused by electrochemical reactions.As an analytical method,ECL possesses advantages of low background,high sensitivity,strong space-time controllability and simple operation.Therefore,it has been widely used in disease diagnosis,environmental analysis,food security control and other fields.ECL imaging is able to visualize the ECL process.Based on the characteristics of ECL,ECL imaging can achieve high throughput and fast detection,which has attracted extensive attention of researchers.Up to now,ECLimaging has been successfully applied in immunoassay,cell imaging,fingerprint imaging,single-particle detection and study of mechanisms and kinetics of reactions.In future,improving the imaging resolution and reducing the imaging scale are the important development directions of ECL imaging.This thesis focused on ECL imaging at micron-sized single-particle level and conducted the reaserch on the preparation and characterization of ECL particle.Furtheremore,the mechanism of single-particle ECL was studied via ECL imaging.The work could be divided into following 4 chaptersThe first chapter overviewed the basic principles and development of ECL imaging.Then,several common ECL imaging systems and their ECL mechanisms were introduced,including luminol,bipyridine ruthenium and quantum dot.Finally,concentrating on ECL imaging of the single-particle,the synthesis of the ECL particle,the equipment of ECL imaging and its applications were reviewed in details.The second chapter introduced the preparation of microbead with high ECL activity.The microbead was modified by ECL moecules,which were vinyl-functionalized ruthenium complex or iridium complex.Through the"click reaction"between thiol and vinyl,ECL molecules could be covalently attached to the SiO2 microbead which was pre-modified by sulfydryl to form the ECL object.As shown by the experimental result,the modification method was highly effctive,easy and controllable,so that ECL imaging of single micro-sized particle was achieved based on the prepared microbead.In the the third chapter,the ECL mechanism of single-microbead was studied by using ECL imaging technology.SiO2 nanoporous membrane(SNM)was prepared on the surface of the indium-tin oxide(ITO)glass via the Stober-solution growth method.The ECL microbead was isolated from the electrode by the SNM so that the direct ECL and mediate ECL were well separated.Using the SiO2 modified by vinyl-functionalized bipyridine ruthenium complex(Ru-SiO2 microbead)as the ECL object,ECL imaging of the single-microbead on the SNM/ITO electrode was performed.In this case,ECL was generated only by mediate ECL process.After optimizing the concentration of TPrA and the applied oxidation potential,the effect of confined diffusion of TPrA·+(the oxidation product of TPrA)on the midiate ECL was studied via ECL imaging,by changing the thickness of SNM on the ITO.All the researches above were summarized in the last chapter and some existing problems and shortcomings were pointed out as well.Last but not least,some suggestions on future research were given.