Application Of Quantum Dots As Fluorescent Probe In Biology

Quantum dots (QDs) are the new powerful tool in biomedical and nanobiophotonics as a kind of novel fluorescent label and used in many fields. Comparing with narrow excitation, broad emission and narrow Stokes shift of traditional organic dyes, they possess tunable fluorescence emission, high photostability and attractive spectrum with almost symmetrical narrow emission and broad excitation; and they are scores of times as bright as the organic dyes at least. Due to such optical properties and with the development of the sensitive microscope, in these years more and more important results have been achieved in bioimaging and assay such as cell labeling, signal transmission, biomolecular detection and immunoassay. This thesis mainly focuses on the application of QDs in biology, especially in the cell labeling and immunoassay. The main results are as the following:1. QDs with different colors that made in our laboratory were used to label the different cells. With the help of microscope, the different colors and the different fields of the cells were observed. This work will be helpful in biology science.2. Red QDs were conjugated to mouse anti-human CD71 monoclonal antibody (McAb anti-CD71/QDs) and green QDs labeling goat anti mouse IgG. (IgG./QDs). The red McAb anti-CD71/QDs were firstly labeled tumor cells successfully, and then green IgG./QDs was added to bind labeled McAb anti-CD71/QDs on the cell surface by immunoreaction. As the collected fluorescence spectra and the figures shown, the"red peak intensity increased and in the same time,"green"one decreasing. The results show that fluorescence resonance energy transfer (FRET) occurs between these two kinds of QDs on the cells. Therefore, the FRET based on multicolor QDs enhances the reliability for immunoassays of antigen/antibody, and accomplish the specific identification of tumor cells.3. QDs conjugated to transferrin (Tf) can conjugation efficiently to the transferring receptors on the cells. We used Tf and QDs/ Tf to compete with each other for the receptors. The results proved that the QDs/ Tf have the same function with Tf. Thus the molecules which labeled by QDs still have the same function with the unlabeled.