Controllable Preparation, Structure,Morphology Regulation And Luminescent Property Of Aliphatic Biodegradable Photoluminescent Polymer-Semiconductor Quantum Dot Fluorescent Nanocomposites,and Rare Earth Luminescence Nanacrystals

Fluorescent label has played an important role in bio-applications such as life sciences, medicines and corresponding interdisciplinary areas. Currently, the most widely used fluorescent materials for biological labeling application are organic dyes and fluorescent proteins, quantum dots, and rare earth luminescent nanomaterials. The organic dyes and fluorescent proteins are less photostable, and exhibit rapid photobleaching and serious photodegradation. Therefore, such disadvantages would make them difficult to label and track with a long period of time and greatly hinder their applications. Semiconductor quantum dots as novel fluorescence label hold great promise for many applications such as biological fluorescent label, targeted recognition, and medical therapy due to their high fluorescence efficiency, broad excitation and narrow emission, high photostability, good anti-bleaching ability, and tunable fluorescent colors. However, the chemical instability and biological toxicity of semiconductor quantum dots confine its further applications. The rare earth luminescent nanomaterials are thought of having more extensive applied foreground in life sciences and medicine fields because of their unique luminescent property, stable chemical property, and high optical stability.Based on the above research background, systematical explorations have been carried out for the controllable preparation, structure, morphology regulation and luminescent property of aliphatic biodegradable photoluminescent polymer-fluorescent semiconductor quantum dot nanocomposites, and rare earth visible and up-conversion nanomaterials. Meanwhile, we investigated the biological fluorescent imaging in breast cancer cells MCF-7using fluorescent semiconductor quantum dot-aliphatic biodegradable photoluminescent polymer nanocomposites as biological fluorescence labels.(1) A series of novel biodegradable photoluminescent polymers of BPLPs were synthesized by the condensation of citric acid, aliphatic diol and a variety of amino acid. Fluorescence property, biocompatibility, and chemical stability of biodegradable photoluminescent polymers of BPLPs are systematically studied. In the meantime, semiconductor CdTe quantum dots that show high fluorescence efficiency were synthesized by a soft chemical method. Furthermore, aliphatic biodegradable photoluminescent BPLPs polymer-fluorescent semiconductor CdTe quantum dot nanocomposites exhibiting dual emitting colors were synthesized by modifying the surface of semiconductor CdTe quantum dots with biodegradable photoluminescent BPLPs polymers, and the in-vitro biological fluorescent imaging in breast cancer cells MCF-7was explored using the dual emitting color nanocomposite as fluorescent labels.(2) Cubic phase (a-) and hexagonal phase (β-) NaYF4:Eu3+/Tb3+, hexagonal phase Y(OH)3:Eu3+/Tb3+and Y2O3:Eu3+nanocrystals were successfully synthesized by solvothermal method using oleic acid, oleic acid-oleylamine, and oleylamine as surfactants, respectively. The influences of Eu3+/Tb3+doping concentration, temperature, time, precursor, additive and surfactant on the size, morphology, microstructure and fluorescence property of NaYF4:Eu3+/Tb3+, Y(OH)3:Eu3+/Tb3+and Y2O3:Eu3+nanocrystals were systematically investigated. The relation between the size, morphology, microstructure of NaYF4:Eu3+/Tb3+nanocrystals and their fluorescence property was explored. Furthermore, the phase transform mechanism from cubic to hexagonal phase and the formation mechanisms of different morphologies of NaYF4:Eu3+/Tb3+nanocrystals were proposed.(3) NaYF4:Yb3+,Er3+/Tm3+upconversion luminescence nanocrystals were successfully synthesized by solvothermal method using oleic acid, and oleic acid-oleylamine as surfactants. The influences of Yb3+,Er3+/Tm3+doping concentration, temperature, time and surfactant on the size, morphology, microstructure and fluorescence property of NaYF4:Yb3+,Er3+/Tm3+upconversion luminescence nanocrystals were systematically studied. The surface of NaYF4:Yb3+,Er3+/Tm3+upconversion nanocrystals was functionalized by surface oxidation method. Meanwhile, their biocompatibility and water solubility were improved, which lays a foundation for the further study of biological imaging.(4) The conclusion of current research was summarized. In addition, the further extension of the research based on this dissertation were suggested.