| Flavonoids compounds were widely used in the fields of antitumor and antioxidative activity due to their special characteristics. Schiff base ligands and their metal complexes also possess a number of biological activities. Based on these reasons, we aimed to prepare some compounds with better biological activities. In this paper, we have synthesized and characterized a series of flavonoids Schiff base ligands and their metal complexes, including transition metal complexes and rare earth metal complexes. And we investigated their biological activities, such as DNA binding properties, antioxidant activities and so on. Magnetic nanoparticles are also applied in biomedicine area. They can be used as biological separation, ion sensors, magnetic resonance imaging contrast agent, drug delivery et al. And in this paper, we studied their uses on ions detection and magnetic resonance imaging contrast agent. The paper can be divided into four parts:1. A brief review on the biological activities of flavonoids and their metal complexes was given, and then the preparation, functionalization and biomedicine application of magnetic nanoparticles were summarized.2. In order to pursue more efficient antitumor drugs and antioxidants, we have prepared a series of flavonoids ligands and their metal complexes. Their structures were characterized by physicochemical methodologies, such as elemental analysis, infrared spectra, ultraviolet visible spectra, mass spectra, X single crystal diffraction and so on. We also investigated their biological activities. Their DNA binding mechanism and affinity were determined by ultraviolet visible titration, fluorescence spectra and viscosity measurements. Experimental results indicated that the flavonoids ligands and their metal complexes can intercalate into DNA base pairs, and the metal complexes can bind to DNA more strongly than the free ligands, showing that they are efficient potential antitumor drugs. In addition, we also studied the antioxidant activities of the ligand and their metal complexes by scavenging superoxide radical and hydroxyl radical effects in vitro, indicating that they are effective antioxidants and the antioxidant activity of the metal complexes is higher than that of the free ligand.3. Zinc ions are very important in the process of life, and the detection of zinc ions is also quite necessary. In this paper, we prepared the magnetic iron oxide nanoparticles via high-temperature decomposition of iron(III) acetylacetonate, and we functionalized them by high biological compatibility polyethyleneglycol derivatives. Quinoline derivatives were also coupled onto the surfaces of magnetic nanoparticles, and the new nanosensor was prepared. This kind of nanosensor can be used to detect zinc ions on the specific organs in aqueous media. The novel approach to devise nanosensor can be applied to design other water soluble nanosensors and eliminate toxic ions.4. Gd3+-DTPA is T1contrast agent, which is the first clinical MRI contrast agent; iron oxide nanoparticles are a kind of new T2contrast agents. We prepared the magnetic iron oxide nanoparticles via high-temperature decomposition of iron(III) acetylacetonate, and we functionalized them by high biological compatibility polyethyleneglycol derivatives. And the new contrast agent was prepared by coupling contrast agents based on gadolinium coordination compounds onto the surface of iron oxide nanoparticles. The new contrast agent not only enhanced the targeted ability of traditional contrast agents, but also increased the spin-lattice relaxation time to62.58mM-1s-1, which is almost8times as great as the traditional contrast agent, magnevist.
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