The Preparation And Analytical Applications Of New Luminophores

Carbon-based quantum dots(CDs)containing sp2 carbon structures and functional groups are considered as zero-dimensional nanomaterials.Due to the quantum confinement and edge effects,CDs exhibit many unique optical properties such as photoluminescence,chemiluminescence and electrochemiluminescence.Recently,CDs have attracted significant attention from researchers and have been widely used in many fields,including drug delivery,biological imaging,optical sensing,etc.This thesis consists of following four chapters.In chapter 1,the definition,synthesis methods,properties and applications of CDs were introduced.Furthermore,the purpose and significance of thesis work was put forward.In chapter 2,fullerene structural carbon based dots(f-CDs)were synthesized for the first time by chemically oxidizing fullerene molecules(C60)using concentrated HNO3.The lateral sizes of the f-CDs distributed in the range of 7-20 nm,and the heights mainly ranged from 0.4 to 1.3 nm with an average value of 0.7 nm.The presence of massive pentagonal carbon units made the f-CDs different from most of graphitic-CDs(g-CDs)both in structure and morphology.The f-CDs exhibited unique luminescent properties such as photoluminescence and electrochemiluminescence.Based on the investigation of the UV-vis absorption and luminescent properties,a novel and reasonable model has been proposed for the PL mechanism of f-CDs.Furthermore,the obtained f-CDs showed low cytotoxicity and would have potential application in cell imaging.In chapter 3,a fast,simple and sensitive method to detect trypsin was established based on our synthesized 3,5-dihydro-5-oxo-2H-thiazolo[3,2-a]pyridine-3,7-dicarboxylic acid(TPA)with high fluorescence quantum yield(FLQY).In the study,we found that positively charged cytochrome(Cyt C)could combine with negatively charged TPA and resulted in a significant quenching of the blue FL emission of TPA.The quenched FL could be recovered by trypsin via enzymatic degradation of Cyt C.On the basis of these FL interactions,sensing methods can be developed for the detection of Cyt C and trypsin.Under the optimum experimental conditions,there was good linear relationship between the FL intensity and Cyt C concentration in the range from 0.03 to 10?M,with a detection limit(S/N=3)of 0.03?M,and there was good linear response for trypsin in the range of 6 nM to 6 ?M,with a low detection limit(S/N=3)of 3.7 nM.In chapter 4,a universal,rapid,sensitive,highly specific immune method for AFP was established by preparation of Ag@CDs@Au composite nanomaterials as SERS-active substrates.Before sensing,some AFP antibody was labeled with p-aminothiophenol(4-ATP),while the other AFP antibody was immobilized on the Ag@CDs@Au SERS-active substrates.AFP antigen was indirectly tested through sandwich immunoreactions between AFP and the labeled antibody,and between AFP and immobilized antibody on the substrates,and the SERS signals of the labeled 4-ATP in the sandwich complexes.Then under the optimum experimental conditions,the linear response range of AFP antigen was from 0.01 ng mL-1 to 20 ng mL-1,and the detection limit was 0.01 ng mL-1(S/N = 3).