Preparation Of Multifunctional Iron Oxide Nanoparticles And The Application Of Magnetic Resonance Imaging

Due to the good biocompatibility,iron oxide nanoparticles are widely used in biomedical fields,such as nuclear magnetic resonance imaging,drug delivery and tumor therapy.However,the iron oxide nanoparticles without surface modification are easily oxidized in air.Furthermore,these unmodified nanoparticles tend to agglomerate due to the high specific surface area and strong magnetic dipole interaction.In view of the above problems,iron oxide nanoparticles can be modified with water-soluble polymers,inorganic materials and biological macromolecules to obtain uniform particle size and good biocompatibility.This paper designed and synthesized the polymer ligand-dodecanthiol-polymethacrylic acid(DDT-PMAA)and pentaerythritol tetrakis 3-mercaptopropionate-polymethacrylic acid(PTMP-PMAA)to modify iron oxide nanoparticles.The morphology,particle size,structure,stability,cell toxicity of the nanoparticles was characterized.The potential of the nanoparticles used as contrast agents in MRI were further explored.The details are summarized as follows:(1)In this study,magnetic iron oxide nanoparticles prepared by the functionalized polymer ligand DDT-PMAA had good water solubility under a wide pH range and high salt concentration due to rich carboxyl functional groups on the surface of the particles.The nanoparticle powder obtained by steaming can be stored for a long time.The effects of molecular weight and concentration of polymer ligands on the size of magnetic nanoparticles were investigated.The magnetic nanoparticles have good biocompatibility:the cell survival rate measured by the CCK-8 reagent method at 400 u g/mL concentrations reached more than 80%.After 3 and 14 days of the tail vein injection,the mice were sacrificed and the main organs such as the heart,liver,spleen,lungs and kidney were collected for HE staining detection.Compared with control group,the glomeruli were not found in the liver cells and the glomeruli were obvious.There was no obvious tissue damage and inflammatory reaction,no necrosis and blood retention occurred.In vitro and in vivo,the nanoparticle as a T1 contrast agents achieved good results and showed great potential in the field of MRI.(2)In this study,magnetic iron oxide nanoparticles with high water solubility,high saturation magnetization and uniform size were prepared by coprecipitation method using the multi-functional water-soluble polymer PTMP-PMAA as the ligand and the various functional groups on the surface could be further modified to meet the requirements of various biological applications.In the process of magnetic nanoparticle generation,the carboxyl group of the multifunctional water-soluble polymer ligand PTMP-PMAA can form Fe-O bonds with Fe3O4 to improve the stability of particles.The size of iron oxide nanoparticles can be controlled by changing the molecular weight and concentration of polymer ligands.The results of XRD indicate that the synthesized Fe3O4 nanoparticles were spinel structure.The magnetic nanoparticles had good biocompatibility:even the concentration reached 400 g/mL,the cell survival rate still maintained a high level.After the injection of the magnetic nanoparticles,no obvious inflammatory and tissue damage has been found in the histological analysis of the mice.In vivo and in vitro,T2-weighted MRI achieved good results.It can be seen that the PTMP-PMAA stabilized iron oxide nanoparticles have good biocompatibility and can be further modified because of their rich surface carboxyl functional groups,such as treatment,targeting and biomarkers.