Synthesis Of Surface Modified Quantum Dots And Their Applications

Quantum dots (QDs) have attracted much attention in the last two decades due to their outstanding fluorescence property. A limitation of QDs is their surface defect which makes them unstable and causes the non-radiation reorganization between electron and hole, thus affecting the optical properties of quantum dots. To avoid surface defect, many organic and inorganic materials can be employed to modify the QDs, which could relatively change their luminescence, increase their water solubility as well as biocompatibility.Thus, based on the current developments in our group, we explored the synthesis of surface modified quantum dots. By combining the QDs with ECL and other technologies, they could be applied in the detection of biomolecules and metal ions. The major contents were described as follows:1. High-efficient energy funneling based on electrochemiluminescence resonance energy transfer in graded-gap quantum dots bilayers and the application in immunoassayA microwave-assisted method was used to synthesize different sized CdSeTe@ZnS-SiO2QDs by simply varying the reaction time. And they had perfectly matched excitation and emission spectra, thus made them an ideal material as acceptor-donor pair for ECLRET-based systems. The CdSeTe@ZnS-SiO2QDs with different sizes were conjugated to glutaraldehyde-activated chitosan on the glassy carbon electrode (GCE) surface layer by layer. By combining the system with ECL technology, the ECL signals increased significantly. We also developed a novel ECLRET immunosensor for carcinoembryonic antigen (CEA) detection. This approach provided a sensitive response to CEA in a wide range from0.01pg mL-1to100ng mL-1with a detection limit of0.009pg mL-1. And the immunosensor showed great specificity, reproducibility and stability. These properties indicated that the ECLRET in QDs bilayers could allow the development of a simple but highly sensitive method for the detection of antigen, and the method showed exciting potentials in developing advanced nanostructures and biosensors.2. Microwave-assisted synthesis of chiral quantum dots and their application in the detection of Co(Ⅱ)The chiral CdSeTe QDs were synthesized with D-and L-cysteine by microwave irradiation. To study their properties, XPS, FT-IR spectra and circular dichroism (CD) were employed to measure the chiral QDs. The QDs showed good luminescence and great water solubility. A strongly selective change by Co2+ions was investigated, as a result, chiral CdSeTe QDs could be used in the detection of Co2+. Moreover, chiral QDs can be widely applied in analytical chemistry and life science.