Preparation And Study Of Fluorescence-encoded Magnetic Nanoparticles Based On CdSe@ZnS QDs And Fe₃O₄

The fluorescent magnetic bifunctional material has played a very important role in biological analysis and can be applied to fluorescence imaging and magnetic resonance imaging at the same time,and possessing higher imaging sensitivity and accuracy.It has broad application prospects in the areas of disease diagnosis and treatment.However,for the moment,its preparation method is still not satisfactory,and the microspheres' are generally obtained and are not easily phagocytosed by cells.On this basis,we prepared fluorescent magnetic bifunctional nanoparticles.In this dissertation,based on the red and green CdSe@ZnS QDs and magnetic nanoparticle Fe3O4,nanoscale magnetic fluorescent nanospheres were prepared and some innovative results were obtained.The specific work is as follows:(1)Small particle size green and red CdSe@ZnS QDs were prepared using the seed growth method;firstly,CdSe seeds were prepared by the method of injection at high temperature,and then the amount of precursors was controlled by continuous ion adsorption growth method.The particle size is regulated,and the wavelength of visible light from the green light to the green light and the green light to the red light from the quantum dots can be adjusted.The thermal stability of the quantum dots is studied and tested,and finally,the annealing treatment and the use of the polymer PMMA coating are performed.Quantum dots obtain two kinds of quantum dots with excellent luminescence properties.(2)Using a reprecipitation-coating method,a poly-lysine(PLL)-coated enzyme-modified magnetic fluorescent nano sphere is directly obtained through a one-step reaction,and the process realizes the quantum dot's phase change,from oil phase to water.In terms of optical properties,we mainly prepared 11 kinds of fluorescent codes,and discussed the energy transfer mechanisms of the red and green quantum dots inside the nanoparticles through fluorescence spectra and fluorescence attenuation curves,and used the spectral regularity to obtain more accurate encoding preparation scheme.Magnetic properties are mainly characterized by magnetic separation experiments and magnetic resonance imaging.Magnetic separations were used to screen nanoparticles of different particle sizes,further optimizing the coding structure and accuracy.Finally,four kinds of codes were used to fluorescently label human hepatoma cells(HepG2).The results of confocal imaging showed that the cells were stained with a single color,demonstrating that we successfully prepared higher-quality codes.In this work,a reprecipitation coating method was used to construct nanoparticles with both magnetic and fluorescent dual functions.Among them,the further optimization of the fluorescence encoding can be achieved by the magnetic properties of the nanoparticles,and then the multi-color markers for the four groups of cells can be realized by using the function of the fluorescence encoding.This idea solves the problem of probe scarring in the biomarker and can realize the problem of Batch labeling of different cells and differentiation markers of the same kind of cells.The obtained results have reference to referenced significance for bio-color markers.