Investigation Of Superparamagnetic Nano-Spheres And Nano-Partical Synthesized Through Polyol Process

Magnetic nanomaterials have been widely used in biomedical fields, such as bioseparation, immunoassay, drug and gene delivery, magnetic reso-nance imaging and so on. With the development of biomedical research, it is essential and necessary to optimize the physicochemical properties of mag-netic nanomaterials to fulfill their functions in biomedical fields.Magnetic nanosphere is a kind of the important magnetic materials, which has been used in biosparation, quantitative immunoassay, drug delivery as mag-netic vector. The diameter, magnetic content, saturation magnetization and surface property of magnetic nanospheres play important roles in their bio-medical applications and determine their moving speed in the solution, signal intensity and conjugation with drug or biomolecules. It is essential to realize the controllable synthesis of magnetic nanospheres with tunable physico-chemical properties. Polyol method has been proved to be a facile synthetic method for metal and metal oxide nanomaterials. Recently, synthesis of mag-netic nanosphere by polyol process has attracted more and more attention of chemical and materials researchers due to the one-pot synthetic route and the well controlled properties for the resultant. However, the mechanism of the formation of magetic nanosphere in polyol process has not been well under-stood by far, it is still a challenge to accurately synthesize the magnetic nano-spheres with controllable physicochemical properties by polyol process. In the first section of this paper, carboxylates functionalized magnetite nano-spheres were synthesized in one-pot through polyol process. The effect of H2O, surfactant, reaction time and temperature on the produced nanospheres was systematically investigated. The prepared magnetite nanospheres were uniform in size and their size could be tuned range from about 200nm to 460nm. The magnetic content of the nanosphere was more than 90wt%. The magnetite nanospheres were superparamagnetic at room temperature and their saturation magnetization was as high as 74emu/g. The carboxylate molecules were bond on the surface of the magnetite nanosphere, which would facilitate their conjugation with bioactive molecules. Base on the systematical investi-gation of the reaction parameters, the mechanism of the formation of the magnetite nanospheres in polyol process were primarily interpreted. With the tunable physicochemical properties, the magnetite nanospheres will have good potential in biomedical applications.Magnetic nanoparticle was another kind of the important magnetic mate-rials that has been widely application in biomedical fields. As magnetic reso-nance imaging (MRI) contrast agent, superparamagnetic iron oxide nanopar-ticles are nontoxic, high sensitive and possess long imaging window time, which also made them become good candidate as the probe in cellular and molecular imaging. The size, stability in aqueous solution and magnetic prop-erty are predominant properties for their application in MRI. In the second section of this paper, nearly monodispersed magnetite nanoparticles were synthesized through polyol process and the effects of polyol solvent and sur-factant on the magnetite nanocrystals were systematically investigated. By varying the polyol solvent and the surfactant, the size of the nanocrystals could be tuned from 5nm to 10nm and the saturation magnetization was as high as 70emu/g. The transverse relaxivity of the magnetite nanoparticles was characterized by Bruker mq60 relaximeter. The synthesized magnetite nanoparticles will be promising in the application of MRI and cellu-lar/molecular imaging.