The Preparation,Characterization And Performance Study Of Fluorescent Magnetic Nanomaterials

The important scientific significance of the appearance of nanomaterials is that it leads people to a new level of understanding the nature,the special structure of nanomaterials decides a series of specific effects,so compared with conventional materials,nanomaterials have many special properties,these make nano-materials are widely used now.Fe₃O₄ magnetic nanomaterials exhibit many unique excellent properties,such as superparamagnetic,high coercivity,good saturation magnetization and biocompatibility.These properties make Fe₃O₄ magnetic nanoparticles have a wide range of applications,and has been favored by a growing number of scholars.The fluorescence intensity of quantum dots is 20 times than the most extensive organic fluorescent substance Rhodamine6 G,and the stability is more than 100 times than it,and can detect in the cell long time efficiently.With the development of society,the requirements of material are also getting higher,single-function-material can not meet the needs of biomedical science.Therefore,the combination of fluorescent quantum dots and nanomagnetic properties has important practical significance.This new material has the propertie of magnetic and fluorescent,and solve the problem of the separation of single fluorescent marker after labeling cells,it is expected to have an excellent performance in cross-cutting areas of biology,medicine,and chemistry.So,the selection of the way and materials of connections become the focus of the study.In this paper,we used coupling method,coating method and biocompatible materials to modify Fe₃O₄ magnetic nanoparticles,then connect with the core-shell quantum dots CdSe/CdS,after a series of characterization.We selected the high performance fluorescent magnetic nanoparticles to interact with the BSA,detected its biocompatibility briefly.（1）Preparation of Quantum Dot CdSe/CdS.Core-shell quantum dots CdSe/CdS were prepared in water phase and oil phase.Discussing the properties of CdSe/CdS in water and oil phases from fluorescent intensity,stability,the quantum yield.The results showed that CdSe/CdS prepared in oil phase are better than in water.And research the influence of different concentration of S and stabilizers on fluorescent intensity of CdSe/CdS prepared in oil phase.The fluorescence microscopy and transmission electron microscopy characterization testing indicate that CdSe/CdS QDs not only have good dispersity but also strong fluorescence and stability,fully meet the needs of analysis and detection long time in practical application.（2）Choosing direct coupling method,Fe₃O₄ were modified by（3-mercaptopropyl）trimethoxysilane（MPTMS）.The Fe₃O₄ nanoparticles were synthesized by coprecipitation method,then encapsulated it by MPTMS.Afterwards,their surface are rich in reactive functional group sulfhydryl.The magnetic fluorescent bifunctional material Fe₃O₄/MPTMs@CdSe/CdS were obtained by the strong bond of cooperation between Sulfhydryl and the surface of CdSe/CdS QDS.After various types of characterization,the results showed that: this new dual-function nanoparticle have good dispersion and excellent magnetic.However,influenced by the quenching effect of Fe₃O₄,The fluorescence intensity and fluorescence quantum yields are in low level,and it still needs further improvement.（3）Modified Fe₃O₄ by coating method.To abate the quenching effect of CdSe/CdS quantum dots by Fe₃O₄,we used stober method,the magnetic nanoparticles were added into TEOS in alcohol-water system,coating the magnetic nanoparticles with amorphous silica shells.Rich of functional double bond were contained to the magnetic nanoparticles by modifing with MPTS,With ethylenediamine as the coupling agent,and thioglycolic acid modified CdSe/CdS quantum dots,We got fluorescent magnetic double function material Fe₃O₄/MPTS@CdSe/CdS.The nanocomposites have good relative fluorescence intensity,good dispersion.But because of the influence of the cladding layer,the saturation magnetization intensity of compound was greatly abated.（4）Modified Fe₃O₄ by good biocompatibility material.By use of glycine and methyl methacrylate,greatly enhanced its dispersion and biocompatibility,Then connected with quantum dots,successfully obtained a new kind of fluorescent magnetic nanomaterials Fe₃O₄/MMA@CdSe/CdS,and carried on the characterization analysis.The results showed that: the magnetic responsiveness and fluorescence performance of the composite all met the requirements of actual use.Then make it interacted with BSA in PBS buffer solution,it showed that the composite nanoparticles had good biological compatibility,it can be conjugated with biological macromolecules and generate coordination compounds.