Study On Synthesis And Fluorescence Quenching Of Fluorescent Magnetic Nanocomposite

Multifunctional nanomaterials have huge application potential in biomedical and chemical disciplines.Prominent applications include cell tracking,imaging,separation,drug delivery,and biosensing.In recent years,research on functional nanomaterials with both fluorescence and magnetism has attracted widespread attention in the fields of biology and medicine.These nanoparticles are required to be water-soluble colloids in the biomedical field,rich in water-soluble groups,and have a hydrodynamic size of 10 to 200nm.Therefore,surface modification of a single magnetic substance or a single fluorescent substance has become one of the concerns,and the study of the properties of synthetic materials is more important.In this paper,Fe₃O₄ magnetic nanoparticles are used as the magnetic source,and the core-shell CdTe@CdS quantum dots are used as the phosphor.Fluorescent magnetic nanocomposites are obtained by covalent coupling through activation means.And by studying the fluorescence properties of the material,speculate on the quenching form of fluorescence quenching.And through this feature to obtain potential application value.The main research of this article includes the following aspects:?1?Fe₃O₄ nanoparticles were synthesized by co-precipitation method.The surface was coated with SiO₂ by adding TEOS,and then the surface was modified with carboxyl groups by adding SA to obtain Fe₃O₄@SiO₂ magnetic nanoparticles with carboxyl-rich surfaces.A core-shell CdTe@CdS quantum dot rich in amino groups on the surface was prepared by one-pot synthesis.And by controlling the reaction time,the quantum dots with the highest fluorescence intensity is obtained.Under the activation of NHS and EDC on the carboxyl groups on the surface of magnetic nanoparticles,the functionalized Fe₃O₄@SiO₂-CONH-CdTe@CdS fluorescent magnetic nanoparticles were obtained by covalent coupling.At the same time,performance of fluorescent magnetic nanoparticles was analyzed by XRD,infrared spectroscopy,transmission electron microscopy and photoelectron spectroscopy.The results show that the fluorescent magnetic nanoparticles have good crystallinity,water solubility,excellent fluorescence performance and good magnetic response capability.?2?Under the activation effect of NHS and EDC on the carboxyl group on the surface of folic acid,CdTe@CdS quantum dots are provided with amino groups on their surfaces,respectively,CdTe@Cd S quantum dots,Fe₃O₄@SiO₂-CONH-CdTe@CdS fluorescent magnetic nanocomposites and folic acid Connected.Fluorescence attenuation or even quenching occurs.By adjusting the ratio of folic acid concentration input to the solution,it was found that the concentration of folic acid is linearly proportional to the degree of fluorescence decay.This relationship can be calculated by the Stern-Volmer equation,and the quenching method and quenching mechanism are speculated from the experimental results.The results show that the Fe₃O₄@SiO₂-CONH-CdTe@CdS fluorescent magnetic nanocomposite has a better fitting result than the fitting relationship between the fluorescence intensity obtained by connecting CdTe@CdS quantum dots with different concentrations of folic acid and the concentration of folic acid.?3?Under the optimal fluorescent conditions,the fluorescent magnetic composite material was combined with folic acid for fluorescence tracking in HepG2 cells,and it was found that Fe₃O₄@SiO₂-CONH-CdTe@CdS-FA binds to specific folate receptors in the cells to the cells surface.Moreover,the biotoxicity of the material was tested,and the results showed that Fe₃O₄@SiO₂-CONH-CdTe@CdS material still maintained a higher survival rate of mouse macrophages at a higher concentration.It shows that the material has potential application value in the biomedical direction.