(Electro) Chemiluminescence Of Novel Nanoluminophores And Their Applications In Bioassays

In this dissertation,the state of arts in the field of electrochemiluminescence(ECL),chemiluminescence(CL)nanoluminophores,potential-resolved multicolor ECL and their applications were reviewed.ECL as highly sensitive detection technology has been widely used in bioassays.However,the ECL studies without any coreactant have rarely been reported.In addition,most ECL studies involve single luminophore with a unique emission process.These drawbacks limited their applications in bioassays.In recent years,ECL nanoluminophores as nanoprobes and nanointerfaces have attracted much attention in bioassays,owning to their advantages such as good catalytic activity,CL/ECL activity,biocompatibility,and stability.In this thesis,the ECL behaviors of gold nanoparticles bifunctionalized by luminol analogues/metal complexes(BF-GNPs)were studied.It was found that BF-GNPs could directly generate outstanding ECL emission in neutral and alkaline aqueous solutions without additional coreactant.Furthermore,two methods were developed for the synthesis of two novel CL nanoluminophores.The potential-resolved multicolor ECL and CL properties,mechanisms and their analytical applications of these nanoliminophores were investigated.The main results are as follows:1.The ECL behaviors of gold nanoparticles bifunctionalized by luminol analogues/metal complexes were studied.It was found that BF-GNPs could directly generate outstanding ECL emission in neutral and alkaline aqueous solutions without additional coreactant.The ECL emission of N-(4-aminobutyl)-N-ethylisoluminol(ABE1)and Co2+ bifunctionalized gold nanoparticles(Co2+/DTDTPA/ABEI-GNPs)was over 2 orders of magnitude higher than that of ABEI functionalized gold nanoparticles in neutral and alkaline medium.The ECL mechanisms for all peaks have been proposed.Furthermore,fourteen transition and rare earth metal ions used for metal ions/DTDTPA complexes-ABEI-GNPs were found to exhibit good ECL property.Among them,Co2+/DTDTPA/ABE1-GNPs demonstrated the strongest ECL intensity.Luminol-type CL reagents functionalized on the surface of the nanocomposites such as luminol,isoluminol and ABEI also showed good ECL activity without additional coreactant and ABEI was the best one.Besides,stable and strong ECL emission can be obtained upon continuous pulse potentials.In particular,excellent ECL activity in neutral and weak alkaline medium without additional coreactant implying that BF-GNPs have a good application prospect for the sensitive detection of biologically important compounds occurring at physiological pH.2.A novel nanoluminophore was prepared by coating 5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin(TCPP)and ABEI on the surface of TiO2 nanoparticle(TiO2-TCPP-ABE1),which exhibited unique potential-resolved multicolor ECL emissions using H2O2 and K2S2O8 as coreactants in an aqueous solution.Three ECL peaks,ECL-1 at 458 nm,ECL-2 at 686 nm and ECL-3 at 529 nm,were obtained with peak potentials of 1.05,-1.65 and-1.85 V,which were attributed to the ECL emission of ABEI,TCPP and TiO2 moiety of the nanoluminophores,respectively.Related ECL mechanisms have been proposed as follows:ECL-1 was due to the reaction of electro-oxidized ABEI·-with O2·-by electro-oxidation or chemical conversion of H2O2 and O2;ECL-2 was due to the reaction of electro-reduced TCPP-with SO4·-by electro-reduction and chemical conversion of S2O82--;ECL-3 was due to that the formed SO4·-injected h+ into the valence band of TiO2 nanoparticles,which recombined with electrons from the conduction band to produce light emission.Moreover,inner ECL-RET between ABEI and TCPP moiety of TiO2-TCPP-ABEI nanoluminophores were demonstrated,showing anticipation for more ECL colors.Potential-resolved multicolor ECL from a nanoluminophore was observed for the first time in an aqueous solution.It opens a new research area of multi-color ECL of nanoluminophores,which is of great importance in ECL field from fundamental studies to practical applications.3.The CL behavior of TiO2-TCPP-ABEI was also studied.The nanoluminophore exhibited excellent CL property.Moreover,it was found that the CL of TiO2-TCPP-ABEI could be quenched by trisodium citrate stabilized gold nanoparticles(cit-AuNPs).On this basis,a CL immunosensor was developed for the sensitive detection of copeptin by using TiO2-TCPP-ABEI nanoluminophore as a CL nanointerface.First,TiO2-TCPP-ABEI was conjugated with primary antibody through amide reaction to form TiO2-TCPP-ABEI-Abi,and then blocked by bovine serum albumins.Second,the as-prepared TiO2-TCPP-ABEI-Ab1 was further combined with copeptin through specific reaction between antigen and antibody to from TiO2-TCPP-ABEI-Abi-Ag.Third,cit-AuNPs were conjugated with secondary antibody to form Ab2-cit-AuNPs,and then added to the above system to form sandwich structure TiO2-TCPP-ABEI-Abi-Ag-Ab2-cit-AuNPs.After centrifugation,H2O2 was added to produce CL emission.According to the CL intensity,copeptin could be determined in the range of 5 × 10-12?1 × 10-9 g/mL with a detection limit of 1.54 × 10-12 g/mL.The immunosensor also exhibited good stability,acceptable reproducibility and high specificity and could be used for detecting copeptin in real human serum samples.It is of great application potential in clinical analysis.Furthermore,the proposed strategy may be used for the determination of other antigens if corresponding antibodies are available.4.A self-enhanced dual-color ECL nanoluminophore ABEI-CQD was synthesized by connecting ABEI to the surface of CQDs through amine coupling reactions.The as-synthesized ABEI-CQDs nanoluminophores demonstrated three completely potential-resolved ECL emissions using K2S2O8 as coreactant.In the negative potential range,blue color ECL emission(ECL-1)was obtained at the potential range of-0.23?-0.8 V with peak potential of-0.58 V and green color ECL emission(ECL-2)was obtained at the potential range of-1.25?-2.3 V with peak potential of-1.85 V.In the positive potential range,a blue color ECL emission(ECL-3)could be observed at potential range from 0.85 to 1.5 V with a peak potential of 1.2 V.Related ECL mechanisms have been proposed.It was found that CQDs in this ECL system performed not only as ECL nanoluminophores but also catalysts for the ECL of ABEI by effectively facilitating generation of radicals such as-CO4·2-and O2·-.As a result,three completely potential-resolved ECL peaks were obtain in a single potential process.This ECL nanoluminophores are of important application potentials in multi-complex bioassays,bioimaging and light emission devices.