The Design Synthesis Of The Magnetic Nanocomposites And Their Applications In The Field Of Medical Diagnosis And Organocatalysis

Binary metallic oxide magnetic nanocomposites are a kind of important inorganic functional materials which has special physical and chemical properties. It has attracted great attention in biological molecules of magnetic separation, enzyme reaction, drug-loaded, magnetic resonance imaging (MRI) and organic catalysis. In recent years, the design of multiple functionalization magnetic hybrid nanomaterials becomes an important research subject in magnetic nanomaterial. The study of this thesis is focus on the controllable synthesis of metal oxide magnetic nanomaterial, functional assembly and application in dual mode T1 and T2-MRI contrast agents, catalytic synthesis of quinoxalines and colorimetric biological detection, including the following three research works:1. MnFe2O4 NPs with plate-like shapes, spherical, and cubic can be successfully prepared by simply tuning the amount of acetylacetone iron (Ⅲ) and acetyl acetone copper (Ⅱ) in oleic acid. Magnetism and MR properties of the particles were found to depend on their size and shape. These MnFe2O4 NPs, when conjugated with gadolinium and folic acid (FA), showed a simultaneous bright signal enhancement on the T1-weighted images and significant signal reduction on the T2-weighted image. In vitro MR imaging experiments also show that the developed multifunctional Gd:FA-DTPA-PEG-DIB-MnFe2O4 NPs enable targeted dual-contrast T1- and T2-MR imaging of tumor cells over-expresses the folate receptor in vitro, and the T1- and T2-MRI has been greatly improved. Our results clearly indicate that such an approach of forming multifunctional Gd:FA-DTPA-PEG-DIB-MnFe2O4 NPs is of great significance for T1- and T2-MR imaging of specific cancer cells with high accuracy.2. Monodisperse core-shell structure Fe3O4@Cu2O nanocrystals was synthesized by using acetylacetone iron (Ⅲ) and acetyl acetone copper (Ⅱ) as precursor, thermal decomposition in the the mixture of oil amine and diphenyl ether system. A new three-dimensional (3D) mesoporous hybrid framework Fe3O4@Cu2O-rGO was synthesized by coordinated layer-by-layer assembly between nanosheets of reduced graphene oxide and Fe3O4@Gu2O. This 3D mesoporous framework shows an excellent catalytic performance with a remarkable activity, selectivity (>99%), and strong durability in the synthesis of quinoxalines.3.4 nm MnFe2O4 NPs was prepared by thermal decomposition of oil phase. Combining with 16 nm,18 nm and 27 nm MnFe2O4 NPs, which was synthesized before, were functional modified with DBI-PEG-NH2 to improve the water solubility. These series of modified nanoparticles were showed the inherent peroxidase-like activities in the presence of H2O2 catalyzed the color reaction of TMB (3,3’,5,5’-tetramethyl benzidine).The dynamic tests exhibited different levels of peroxidase-like activities, in the order of 4 nm spherical NPs> 18 nm plate-like NPs> 27 nm cubic-like NPs> 16 nm spherical NPs. After labeled with folate, the nanocomposite can specific catalyze the reaction in the Hela cell in a low Cell toxicity level.