Study On The Cellular Labeling Of Quantum Dots Fluorescent Probes

As a novel kind of fluorescent nano-materials, quantum dots (QDs) have manyexcellent optical properties compared with other fluorescent materials like organic dyes,fluorescent proteins. QDs-based fluorescent probes have been widely used in cell labeling,tissue and in vivo imaging in recent years. In order to realize multifunction in labeling andimaging, QDs are always modified with various and specific biological molecules. Thus, itis essential to evaluate the characteristics of modified QDs. Quantum dots-transferrinconjugates were prepared by three different methods in this thesis, and a complete set ofsystem was established to estimate cell labeling effects of quantum dots-transferrinfluorescent probes. The main results are summarized as follows:(1) Quantum dots-transferrin fluorescent probes were prepared by three differentmethods electrostatic interaction, EDC coupling and denatured transferrin coating, andcharacterized by many approaches like emission spectrums, capillary electrophoresis andzeta potential. The obtained results indicated that the fluorescence intensities of quantumdots-transferrin (QDs-Tf) fluorescent probes prepared by electrostatic interaction, EDCcoupling both decreased compared to QDs, while that of QDs-Tf prepared by denaturedtransferrin coating increased a little. The values of zeta potential of three QDs-Tffluorescent probes decreased, indicating that QDs-Tf colloidal systems of QDs-Tf probesbecame less stable than QDs. In addition, QDs-Tf probes were used to label cells and theirlabeling effects were studied by CCD images and fluorescence spectrums.(2) A simple method has been established to detect cell labeling efficiency ofquantum dots (QDs) probe. Briefly, the labeled cells were injected into the capillary bymicro-flow injection pump, and passed through the detection window one by one underliquid flow driven pressure. Then labeling efficiency was calculated through statisticalanalysis of cellular fluorescent signal collected by dual-channel spectrometer. Using this system, the HeLa Cells labeling efficiency of CdTe/CdSe QDs-transferrin (QDs-Tf)fluorescent probes prepared by three different methods, electrostatic interaction, EDCcoupling and denatured transferrin (dTf) coating were investigated, and labeling efficiencywere found to be78.86±9.57%,85.55±3.88%,40.09±10.2%, respectively. The resultsshowed that the efficiency of EDC-coupled QDs-Tf probe was the highest and QDs-dTfprobe was the lowest, which is corresponded to the results obtained by flow cytometry. Inconclusion, this method is simple, fast, low-cost, and can keep the activity and integrity ofcells, and it can be used to study the cell labeling efficiency and other fields in quantumdots probe research.