Design Of Novel Electrochemiluminescence Systems And Their Applications In Biochemical Analysis

People care more about health in modern society,thus having higher requirements and expectations towards food security,environmental protection and medical treatment.The development of analytical methods with high-sensitivity,high-throughput,universal and versatile features and the fabrication of miniaturized and portable detection devices are particularly urgent,in which electrochemiluminescence(ECL)analysis could plays a significant role.ECL combines the advantages of both electrochemistry and chemiluminescence.On one hand,it is fast and could be controlled spatio-temporally as in electrochemical analysis;On the other hand,it has a high sensitivity and a wide linear range that chemiluminescent detection has.Since the first observation of light generated from the electrode surface,the research scope of ECL has expanded continuously with many new ECL systems established.The ECL generation mechanisms and reaction kinetics have also been investigated thoroughly over the past several decades.Nowadays,ECL has become a versatile analytical technique and has been widely used in many fields,such as clinical diagnosis,food security and environmental monitoring.The great market demand of portable and miniaturized devices for point of care testing provides an excellent chance to develop ECL based detection kits.This thesis focuses on the fundamental scientific questions involved in the ECL bioanalysis including sensitivity,stability,selectivity and speediness.We aim at developing ECL sensors with better performance through chemical modification of electrode surfaces and synthesis of new ECL emitters.The first chapter describes the basic definition,characteristic and brief history of ECL.Then,different ECL emitters and co-reactants are introduced,with the emphasis on two dominant reaction routes for ECL generation,annihilation pathway and co-reactant pathway.Finally,the chapter focuses on the research progresses of the ECL applications in the analytical chemistry field.In the second chapter,a bipolar electrode sensor fabricated on an ITO glass plate is reported.The bipolar electrode is T-shaped and modified with a thin film consisting of silica mesochannels(SMCs).Owing to the strong electrostatic interactions between negatively charged SMCs and positively charged tris(2,2'-bipyridyl)ruthenium(?)(Ru(bpy)32+),the SMCs increased the sensitivity for tri-n-propylamine(TPrA)analysis by more than two orders of magnitude.Moreover,the SMCs with ultrasmall channels served as an antifouling layer of the underlying ITO electrode,allowing the ECL detection of atropine and L-proline in human blood serum.The third chapter reports the synthesis of a vinyl-functionalized bipyridine ruthenium complex,bis(2,2'-bipyridine)(4,4'-di(4-vinylphenyl)-2,2'-bipyridine)ruthenium(?)hexaflurophosphate(Ru(bpy)2(dvbpy)(PF6)2).Time-resolved ECL spectra were recorded using a homemade ECL spooling system.The complex was then covalently attached to the pre-modified indium tin oxide electrode as a monolayer film to fabricate a solid-state ECL sensor.The forth chapter describes the synthesis,photophysics,electrochemistry and ECL of a series of ruthenium and iridium complexes based on Ru(bpy)32+ and tris(2-phenylpyridine)iridium(?)(Ir(ppy)3).The ECL emission wavelengths of these six complexes vary from 491 nm to 636 nm.Among them,(4,4'-di-tert-butyl-2,2'-bipyridine)bis(2-(2,4-difluorophenyl)-5-trifluoromethylpyridine)iridium(?)(Ir(dFCF3ppy)2(dtbbpy)~+),Ir(ppy)3 and Ru(bpy)2(dvbpy)2+are selected as the cyan-,green-,and red-ECL generating emitters.The ECL behaviors of individual emitters and their mixtures are investigated in details via multidimensional ECL measurements,including intensity,spooling and imaging.The potential-resolved ECL emissions have been achieved by introducing Ir(ppy)3 into either Ru(bpy)2(dvbpy)2+ or Ir(dFCF3ppy)2(dtbbpy)~+ systems,and the 'switch on-off effect of Ir(ppy)3 was investigated by Electrochemistry-Mass spectrometry(EC-MS).The ECL spectral peak separation between Ru(bpy)2(dvbpy)2+ and Ir(dFCF3ppy)2(dtbbpy)~+ is up to 145 nm,providing the spectrum-resolved possibility.Finally,a multiplex immunoassay was established in which antibody pairs provided the specificity to capture antigen and ECL served as readout signal.As a demonstration,the simultaneous determination of carcinoembryonic antigen(CEA),alpha-fetoprotein(AFP)and beta-human chorionic gonadotropin(?-HCG)was achieved in a single run.Chapter 5 summarizes the thesis work and provides a prospect for the future of ECL.