Rearch On Cathodic ECL Of CdSe/ZnS QDs And Its Quenching Effect By Heavy Metals Ions

Electrochemiluminescence is the combination of electrochemistry andchemiluminescence analysis. It involves generating intermediates electrochemically atelectrode surfaces via applied voltage and then undergoing a highly energeticelectron-transfer reaction. Afterwards, the luminescent reagents produce excited stateand emits a photon of light when the excited molecule returned to the ground state. Inthe past decades, ECL has been paid considerable attention due to its low back groundsignal, high sensitivity, simplified optical setup, good temporal and spatialcontrollability. Based on the quenching effect of heavy metal ions to ECL of QDs inthis thesis, we successfully established two sensors for detection of heavy metal ions.The main contents are summarized as follows:Chapter I?We have constructed an optional QDs-ECL sensor to detect heavymetal ions (Pb2+). Due to4-ATP had two functional group(-NH2and-SH) to formC-N and S-Cd respectively, it was used to combine GC electrodes and QDs. Owing tothis method, QDs could be immobilized firmly on the electrodes. Then, strong ECLsignal was observed and it could be quenched by trace amounts of heavy metal ions.However, Pb2+had the strongest quenching effect among different ions. What's more,ECL intensities had good linearity with the concentration of Pb2+and the linear rangewas widely extended from0nmol L-1to75.6nmol L-1. The detection limit was0.99nmol L-1.Chapter II?We have constructed an optional QDs-ECL sensor to detect heavymetal ions (Hg2+). Owing to L-cys had-NH2and-SH at the same time, it was used tocombine GC electrodes and QDs. QDs could also be immobilized on the electrodesfirmly through this way. Then, strong ECL signal was observed and it could bequenched by trace amounts of heavy metal ions. However, Hg2+had the strongestquenching effect among those different ions. What's more, ECL intensities had goodlinearity with the concentration of Hg2+and the linear range was extended from0nmol L-1to7.70nmol L-1. The detection limit was0.83nmol L-1.Chapter III: We have tried a new method to produce ECL singal. The modified GC electrodes electrodeposited by CdS NPs could generate stable ECL peak inweak-acid solution. However, the ECL signal was not quenched after adding differentheavy metal ions. It could open a new avenue in this field of ECL-sensor in the future.