| Quantum dots(QDs),one of the most promising new materials released at the"2016 New Materials Capital Technology Spring Summit",are extremely small semiconductor nanocrystals that exhibit high brightness,tunable emission wavelength,wide excitation spectrum,narrow emission spectrum,long fluorescence lifetime,and high photobleaching resistance,QDs have attracted widespread attention in medicine,solar cells,display lighting and other fields in recent decades.At present,the research more mainly ?-? binary QDs,such as CdS,CdTe,CdSe,CdS/ZnS QDs etc.However,the release of heavy metal ions Cd2+ or Pb2+ will produce high toxicity,which will affect the environment and human health to varying degrees,even lead to death.Therefore,the development of QDs that do not contain toxic heavy metal elements to replace binary QDs based on Cd2+ or Pb2+ has important research and application value.Type ?-?-? QDs is a new type of QDs that has emerged in recent years.It overcomes the problem of traditional QDs containing heavy metal elements that are more toxic to the environment and biological systems.It can effectively reduce the biological toxicity and environmental pollution of QDs and meet the current environmental protection requirements.Among them,CuInS2 is non-toxic,has a high sunlight absorption coefficient,stable photochemical performance,and its fluorescence wavelength covers the visible light region to the near-infrared region.At the same time,CuInS2 QDS has large Stokes shift,long fluorescence lifetime,longer emission wave can reduce the interference caused by external excitation wave,which is beneficial to the application of biological imaging.Therefore,this paper designed and synthesized a variety of green and environmentally friendly water-soluble CuInS2 QDs bioluminescent nanoprobes to achieve the goal of reducing toxicity and environmental protection,and to meet the current strategic requirements for environmentally friendly materials.The research content of this paper is mainly divided into three parts.The first two parts are the design,synthesis and bio-fluorescence imaging application of three novel green and environmentally friendly water-soluble CuInS2 QDs based on natural carbohydrates,and systematically studied the sugar-based CuInS2 QDs nanomaterials,which performed microscopic appearance,fluorescence performance,cytotoxicity and fluorescence imaging ability of tumor cells.The third part is the design and synthesis of two environmentally responsive water-soluble polymers/CuInS2 QDs nanocomposites based on the reversible addition-fragmentation chain transfer(RAFT)polymerization technology,and coordinate with the rare earth element Eu(?)to form a polymer/CuInS2 QDs nanocomposite with dual fluorescence emission function,and systematically study the microscopic morphology,dual fluorescence performance,cytotoxicity and fluorescence imaging ability of this type of polymer nanocomposite.The main research contents are:1.Synthesis of water-soluble CuInS2 QDs based on two small carbohydrate molecules and their application in cell imagingFirstly,synthesize glucose and fructose derivatives containing-SH,and then use them as ligands,copper chloride(CuCl2·2H2O),indium chloride(InCl3·4H2O)as metal precursors,and thiourea as sulfur source.Using hydrothermal method,under the optimal reaction conditions of temperature 150?,pH=13 or 11,Cu:In:S:ligand=1:1:2:12,two water-soluble glycosyl Glu-CuInS2 QDs and Fru-CuInS2 QDs were synthesized.The test results show Glu-CuInS2 QDs and Fru-CuInS2 QDs have good dispersibility and stability,which average particle size are approximately 5.0 nm.The two QDs emit strong green fluorescence around 500 nm and 546 nm,respectively,and the fluorescence quantum yields are both over 10%.In addition,the aqueous fluorescence of Glu-CuInS2 QDs and Fru-CuInS2 QDs both have temperature,pH,metal ion and neomycin sulfate responsiveness.More importantly,cell imaging studies have proved that Glu-CuInS2 QDs and Fru-CuInS2 QDs both exhibit low cytotoxicity and excellent cell imaging capabilities,and are expected to be an ideal green and environmentally friendly bioluminescent probe.2.Synthesis of water-soluble CS-CuInS2 QDs based on carbohydrate macromolecules and application of fluorescence imaging in cancer cellsFirstly,synthesize chitosan derivatives containing-SH,and then use them as ligands,copper chloride(CuCl2·2H2O),indium chloride(InCl3·4H2O)as metal precursors,and thiourea as sulfur source.Using hydrothermal method,under the optimal reaction conditions of temperature 150?,pH=9,Cu:In:S:ligand=1:1:2:12,water-soluble chitosan based CS-CuInS2 QDs was synthesized.The test results show CS-CuInS2 QDs has good dispersibility and stability,which average particle size was approximately 6.0 nm.That QDs emit strong green fluorescence around 530 nm,and the fluorescence quantum yields is 12.28%.In addition,the aqueous fluorescence of CS-CuInS2 QDs has temperature,pH,metal ion and neomycin sulfate responsiveness.More importantly,cell imaging studies have proved that CS-CuInS2 QDs exhibit low cytotoxicity and excellent cell imaging capabilities,and is expected to be an ideal green and environmentally friendly bioluminescent probe.3.Preparation of two environmentally responsive Eu coordination polymers/CuInS2 QDs nanocomposites and their application in dual-color fluorescence imaging in cancer cells.Firstly,use the mercaptopolyethyleneimine(PEI)with a molecular weight of 600 as the ligand,copper chloride(CuCl2·2H2O),indium chloride(InCl3·4H2O)as metal precursors,and thiourea as sulfur source.Using hydrothermal method,water-soluble PEI-CuInS2 QDs with amino groups on the surface was synthesized.Then a RAFT chain transfer agent containing trithioester structure was bonded on the surface of CuInS2 QDs by amidation reaction,and then two vinyl monomers were initiated by RAFT polymerization method:N-vinylpyrrolidone(NVP)and N-isopropyl Acrylamide(NIPAM)were polymerized on the surface of CuInS2 QDs.Finally,the rare earth ion Eu(?)was added,and the coordination reaction occurs with the poly-Nvinylpyrrolidone(PVP)and poly-N-isopropylacrylamide(PNIPAM)polymers with side chains rich in N and O elements,respectively.To prep are Two-col or polymer/CuInS2 QDs nanocomposites containing rare earth luminescent groups:PNIPAM-Eu(?)/PEI-CuInS2 QDs and PVP-Eu(?)/PEI-CuInS2 QDs.The test results show Glu-CuInS2 QDs and Fru-CuInS2 QDs have good dispersibility and stability,which average particle size are approximately 18 nm.The two QDs emit strong double fluorescence around 460 nm and 615 nm,respectively.The blue and red fluorescence quantum yields are about 10%and 30%.In addition,the aqueous fluorescence of PNIPAM-Eu(?)/PEI-CuInS2 QDs and PVP-Eu(?)/PEI-CuInS2 QDs both have temperature and pH responsiveness.More importantly,cell imaging studies have proved that Glu-CuInS2 QDs and Fru-CuInS2 QDs both exhibit low cytotoxicity and excellent reversible two-color fluorescence imaging capabilities,and are expected to be an ideal environmentally friendly bioluminescent probe.This research method provides simple and feasible ideas and synthetic methods for the design and synthesis of new low-cytotoxic dual-fluorescence emission QDs materials.In summary,the hydrothermal synthesis method used in this study avoids the use of organic solvents throughout the process,and the reaction conditions are relatively mild,easy to operate,and overcome the disadvantages of traditional quantum dot preparation that are relatively toxic to the environment and biological systems.The goal of green environmental protection is achieved.In addition,the water-soluble CuInS2 QDs synthesized in the thesis have excellent luminescence properties and good cell imaging capabilities,especially the realization of reversible two-color fluorescence imaging of organisms by fluorescent probes.Therefore,this research provides a theoretical basis for the extensive application of CuInS2 QDs in the field of biomedicine,and lays a foundation for the biological application of intelligent QDs. |
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