Study On Surfacre Modification Of Magnetic Nanoparticles And Their Biomedical Applications

Biomedical and bioengineering applications require magnetic iron oxide nanoparticles have uniform physical and chemical properties.Such as high magnetization values and size smaller than 20 nm with overall narrow particle size distribution,In addition,these applications need special surface coating of the magnetic particles,which has to be non-toxic and biocompatible but also allow a targetable delivery with particle localization in a specific area.we reviewed various methods of preparing magnetic iron oxide nanoparticles and various surface-modification methods of magnetic nanoparticles.In additionally,A simple introduction of Biomedical and bioengineering applications of magnetic nanoparticles was metioned to make a base in theory for putting forward our research topics.The research topics of this thesis are to prepare novel magnetic nanoparticles with excellent physical and chemical properties,then study their biomedical applications.1.Using a simply method,magnetite nanoparticles were successfully modified with PMA.The characterization of the surface- modified Magnetite nanoparticles were examined by FT-IR,TGA.The result proved that PMA-modification not only increases magnetite nanoparticles biocompatibility and water solubility,also provides active group which can be attached to biomolecules.This kind of magnetic capture probe of DNA segments can be obtained by using the resultant magnetite nanoparticles.PMA-modified magnetite nanoparticles were coupled with amino-modified oligonucleotides,then complementary to biotin-modified target oligo sequence.The fluorescence images were obtained on a fluorescence microscope by biotin group specific binding with SA-PE.Oligonucleotide-modified magnetite nanoparticles have been shown great potential application as nanoparticle probe. 2.A two-step procedure was employed to obtain amino acid surface-modified iron oxide nanoparticles.First,OsO₄/NaIO₄ were used as oxidant of alkene group of oleic acid which capped on the magnetic nanoparticles in room temperature.In this step, the nanoparticles capped by aldehyde group were obtained in a mild condition.Then amino acid-surface modification for nanoparticles was completed by a reaction of -NH₂ of amino acid with aldehyde group on the nanoparticles.3.Superparamagnetic magnetic nanoparticles showing excellent water-dispersion were prepared through glucosaminic acid-surface modification of iron oxide nanoparticles coated with aldehyde group.In cell culture experiment,glucosaminic acid modified magnetic nanoparticles(GA-MNPs) internalization into different kinds of cells were observed for 5 days.The results of light microscopy indicated GA-MNPs internalization into mouse macrophage cells(RAW264.7) and mouse embryonic fibroblast cells(3T3) almost can not be found within 40 h of culture.For cancer cells,GA-MNPs were internalized quickly into human endometrial adenocarcinoma cell,colon carcinoma cell and human esophageal cancer cell after just 24 h of culture.Also inductively coupled plasma emission spectroscopy(ICP) measurement also showed that the uptake amount of GA-MNPs into cancer cells was much higher than that into RAW264.7 and 3T3 cells.TEM images of GA-MNPs uptake to ECA-109 cells were used to study internalization mechanisms of GA-MNPs and distribution of GA-MNPs in ECA-109 cells.Meantime,soluble magnetic capture probe was prepared by immobilization of oligonucleotides onto GA-MNPs and used for detection and separation of their complementary oligonucleotides sequence.4.Chitosan surface-modified magnetic nanoparticles were prepared used for cellular uptake to evaluate their potential biomedical applications.