The Preparation Of Multifunctional Magnetic Nanocomposites Based On Lanthanide Complex And Their Application In Ion Senseing And Bioimaging

With the continuous development of nanotechnology,multifunctional magnetic nanomaterials can be prepared after surface modification by various chemical and biological reactions.These multifunctional nanomaterials have attracted extensively attention and have widely application in chemical sensing,bio sensing,cell imaging,drug delivery and magnetic induction hyperthermia.Lanthanide complexes have unique properties of narrow emission band,large Stokes shift and long flurescence lifetime.They can improve the resolution and exclude the interference of nonspecific fluorescence.The nanocomposite of lanthanide complexes and magnetic nanoparticle can be applied to bioanalysis by time-resolved fluoroimmunoassay.Graphene oxide-magnetic nanoparticle composite integrate characteristics of graphene oxide and mangetic nanoparticle.And these composites as a nanocarrier loading a variety of functional molecules can be widely used in biosensing,bioimaging and bioseparation.Using the inherent magnetic,mangnetic nanocomposites have been developed in high sensitivity detection and isolation of heavy metal ions pollutants in the environment,also in capture and magnetic separation of cancer cells in biomedicine field.Under above research background,the developed researches of this paper about the preparation of multifunctional magnetic nanocomposites and their application are described as follows:Chapter one:This parper briefly introduced the properties and surface modification of magnetic nanaoparticle,and simply reviewed the application of lanthanide complexes,graphene oxide,lanthanide-magnetic nanocomposite and graphene oxide-magnetic nanocomposite in environment monitoring and biomedicine.Chapter two:Magnetic fluorescent sensor based on Eu（Ⅲ）complexes modified Fe₃O₄ nanoparticle can be not only high sensitivity and specificity detect Cu²⁺ in aqueous between a wide pH range,but also effective separate excess Cu²⁺ in water.This sensor can also be used to detect Cu²⁺ within cells using fluorescent imaging.Chapter three:Based on dumbbell Au-Fe₃O₄ nanoparticle,Eu（Ⅲ）complexes,Tb（III）complexes and fluorescein isothiocyanate（FITC）were coupled on the two surfaces of Au-Fe₃O₄ nanoparticle to prepare a novel ratiometric magnetic nanoprobe.The excitation wavelengths of these three luminescent materials are matched and the emission spectrum are well-resolved and noninterference in this nanoprobe.FITC as reference signal,Eu（Ⅲ）complexes and Tb（Ⅲ）complexes as response signals,this probe can detect Cu²⁺ with ratiometric method and ratiometric imaging Cu²⁺ in cells.Furthermore,the nanocomposites after Au nanoparticle modified with functional molecule folic acid（FA）in the above probe can targeted image cancer cells.Chapter four:First,the surface of grapheme oxide（GO）covalently modified polyethylene imine（PEI）or the functional groups of GO transformed into carboxyl reacting with polyrthylene glycol derivatives,and then loading Au-Fe₃O₄ nanoparticle.Sensitive molecules of lanthanide ions pyridine dicarboxylic acid derivatives（HS-PEG-DPA）were coupled on Au nanoparticle and the graphene oxide-magnetic nanocomposite was prepared.After folic acid-Eu complexes targeted combined with cancer cells,the DPA molecule on nanocomposite sensitized and enhanced the Eu³⁺fluorescence after the coordination interaction between DPA and Eu³⁺.Captured cancer cells can be detected using fluorescence spectroscopy and be isolated with external magnetic.When hypochlorite is added to the above solution of nanocomposites and cancer cells,Eu³⁺ can coordinate with hypochlorite based on ligand exchange.Therefore,the characteristic spectrum of lanthanide disappeared and captured cells were released.