The Application Of Quantum Dots Based Chemiluminescence And Electrochemiluminescence Systems In Biomedical Analytical Field

Quantum dots (QDs) have been a new class of chemiluminescence andelectrochemiluminescence luminophor in recent years. Compared with conventionalluminophor, QDs have many unique optical properties. In order to expand theapplication of QDs in bioanalytical, two chemiluminescence system and twoelectrochemiluminescence sensors were constructed based on water-soluble CdTeQDs in the present work. Satisfied results were got when they were applied to thespecific detection of biomolecules, pollutant and pathogenic DNA of malignanttumors.In chapter1, a brief review of development of QDs chemiluminescence andelectrochemiluminescence, including the basic properties of QDs, the principle andsystem of flow injection chemiluminescence and electrochemiluminescence and theirapplication in bioanalytical. The design proposal and significance of this work arepresent in the end of this chapter.In chapter2, a flow injection (FI)“turn off-on” chemiluminescent method wasdeveloped for the determination of glutathione (GSH). Strong chemiluminescence(CL) signals were observed from the hydrogen peroxide and CdTe quantum dots(QDs) system under basic condition, addition of trace amount of Cu(Ⅱ) could causedsignificant CL quenching of the CdTe QDs-H2O2system. In the presence of GSH,Cu(Ⅱ) can be removed from CdTe QDs surface via forming Cu(Ⅱ)-S bond withthiols, and the CL signal of CdTe QDs-H2O2system was recovered. Thus, the CLsignals of CdTe QDs-H2O2system were turned off and on by the addition of Cu(Ⅱ)and GSH respectively, and a flow injection CL analysis system for the determinationof GSH was established. Under the optimum conditions, the CL intensity and theconcentration of GSH have a good linear relationship in the range of2.0×109-6.5×107mol L1(R2=0.9993). The limit of detection for GSH is1.5×109mol L1(S/N=3). This method has been applied to detect GSH in human serum with satisfactory results.In chapter3, a novel flow injection CdTe quantum dots (QDs) basedchemiluminescent method was developed for the determination of nitrite. Weakchemiluminescence (CL) signals were observed from the hydrogen peroxide andCdTe QDs system under basic condition. The addition of trace amount of hemoglobin(Hb) can caused significant CL enhancing of the CdTe QDs-H2O2system. In thepresence of nitrite, it would reacted with ferrous Hb, forming ferric Hb and NO.Subsequently, NO bound to ferrous Hb to generate iron-nitrosyl Hb. As a result, theCL signal of CdTe QDs-H2O2-Hb system was quenched. Thus, a flow injection CLanalysis system for the determination of trace nitrite was established. Under theoptimum conditions, the CL intensity and the concentration of nitrite have a goodlinear relationship in the range of1.0×10-9-8.0×10-7mol L-1(R2=0.9957). The limit ofdetection for nitrite is3.0×10-10mol L-1(S/N=3). This method has been successfullyapplied to detect nitrite in water samples.In chapter4, a novel facile signal-off electrochemiluminescence (ECL) biosensorhas been developed for the determination of glucose based on the integration ofchitosan (CHIT), CdTe quantum dots (CdTe QDs) and Au nanoparticles (Au NPs) onthe glassy carbon electrode (GCE). Chitosan displays high water permeability,hydrophilic property, strong hydrogel ability and good adhesion to load the doublenanoparticles to the glassy carbon electrode surfaces. Au NPs are efficient glucoseoxidase (GOx)-mimicking to catalytically oxidize glucose similar to the naturalprocess. Upon the addition of glucose, the Au NPs catalyzed glucose to producegluconic acid and hydrogen peroxide (H2O2) based on the consumption of dissolvedoxygen (O2), which resulted in a quenching effect on the ECL emission. Therefore,the determination of glucose could be achieved by monitoring the signal-off ECLbiosensor. Under the optimum conditions, the ECL intensity of CdTe QDs and theconcentration of glucose have a good linear relationship in the range of0.01-10mmolL-1. The limit of detection for glucose was5.28μmol L-1(S/N=3). The biosensorshowed good sensitivity, selectivity, reproducibility and stability. The proposedbiosensor has been employed for the detection of glucose in human serum samples with satisfactory results.