Surface Modification Of The Quantum Dots And Its Application In Probing

Recent years, Due to their novel photoelectric properties and excellent photoluminescence （PL） property and stability compared to the organic fluorescent dyes, semiconductor quantum dots （QDs） have attracted great interests in both academic and industrial applications such as biomedical imaging, lighting, and photovoltaic devices etc. The recent development indicates that the most direct application of PL QD should serve as fluorophore and used in the biomedical imaging. Therefore, it is necessary to develop a facile and convenient synthesis route, exploit chemical treatment on QD surface in order to improve the bio-compatibility and minimize the toxicity.In chapter one, we first described the concept and basic properties of QDs, followed by the synthesis, phase transfer technology, and the application of QD as fluorophore sensor. Then we made a brief summary of the methods to incorporate quantum dots with polymer micorspheres, the synthesis and properties of the spherical polyelectrolyte brushes.In chapter two, we reported the detection of dopamine （DA） with high sensitivity and excellent selectivity used a water-soluble quantum dot fluorophore probe. The probe was based on the high quality adenosine capped water-soluble QDs, which derived from the initial oil-soluble CdSe/CdS/Cd_0.5Zn_0.5S/ZnS QDs and undergone a phase transfer procedure with use of adenosine as phase transfer reagent. The fact that our reported probe can be used in the detection of adenosine in practical biological fluids demonstrates its value in practical application.In chapter three, we reported the preparation of the quantum dot-polystyrene （QDs-PS） composite microspheres and the fluorescent spherical polyelectrolyte brushes. During the progress of mini-emulsion, with the combination of sonication and agitation, the homogeneous QD/stylene emulsion was obtained. Then initiating the mini-emulsion polymerization, and obtained the QDs-PS composite microspheres. At the same time, we also studied the influence of the nature of initiators on the PL intensity of the QDs-PS microspheres. With the combination of the sonication and agitation, we prepared the colloidal quantum dots aggregate. Via the hybrid emulsion polymerization, QD-PS composite with different morphologies were obtained from the colloidal QD aggregates. Dense linear polyacrylic acid （PAA） was grafted on the surface of the QD-PS microspherical composites through the photo-emulsion polymerization, and the fluorescent spherical polyelectrolyte brushes （FSPBs） were obtained. The PL intensity of the FSPBs is sensitive to pH and ionic strength of the dispersed media. The FSPBs show excellent dispersibility in water with stable fluorescence and therefore can be used as a stable and modifiable fluorescent marker.