The Oil Phase Of Fe <sub> 3 </ Sub> The O <sub> 4 </ Sub> Magnetic Nanoparticles Aqueous Phase Studies And Preliminary Applications

Magnetic nanoparticles of iron oxides have attracted much attention because of their numerous applications in biomedical fields such as nucleic acid purification, magnetic resonance imaging (MRI), drug delivery. Oleic acid (OA) is a commonly used stabilizer in the magnetic nanoparticles synthetic methods. However the nanoparticles stabilized by OA, which were immiscible in the aqueous solution, were greatly restricted their applications in the biomedical field. Therefore, it is indispensable to transfer these magnetic iron oxide nanoparticles to aqueous phase.Our study focuses on the preparation of high quality iron oxide magnetic nanoparticles by thermolysis of iron-oleate complex, the phase transfer of synthesized nanoparticles from organic solvent to water solution in microemulsion system and mixed solution system, and the immobilization of Bovaine serum albumin (BSA) in buffer on the surface of magnetic particles. This work in detail was as follows:1. Preparation of magnetic nanoparticles coated with OAThe Fe3O4 nanoparticles coated with OA were prepared by thermolysis process of iron-oleate complex, and characterized by Transmission electron microscopy (TEM), X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FT-IR) and Vibrating sample magnetometer (VSM). The results showed the synthesized Fe3O4 nanoparticles were spherical and showed superparamagnetic behavior at room temperature. Because oleic acid was chemical adsorpted on the nanoparticles surfaces, the Fe3O4 nanoparticles could be well dispersed in organic nonpolar solvent such as hexane.2. The phase transfer of Fe3O4 nannoparticles in microemulsionThe nanoparticles could be transferred from the organic phase to water in the microemulsion system with NaClO as oxidiative for oleic acid. The phase dispersion experiments of tranfered magnetic nanoparticles shows that the nanoparticles after oxidation could be dispersed in water not in hexane. The shape and components of nanoparticles after phase transfer have no obvious changes by TEM. The characterization of Zeta potential showed that the surface of nanoparticles after phase transfer carried negative electric charge.3. The phase transfer of Fe3O4 nannoparticles in mixed solvents The Fe3O4 nanoparticles could be achieved aqueous transfer in the mixture of hexane, ethyl acetate, acetonitrile and water with NaIO4 as oxidiation for oleic acid. The characterizations showed that the nanoparticles after aqueous transfer have no change in morphology, crystalline and can be well dispersed in water. The magnetic nanoparticles were super paramagnetism at room temperature with the higher saturation magnetization.4. The immobilization of Bovaine serum albuminBovaine serum albumin (BSA) was immoblized on the surface of Fe3O4 nanoparticles with crosslinker of 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in the 2-(N-morpholino) ethanesulfonic acid (MES) buffer. The experimental results showed that the capacity of nanoparticles increased with the initial amount of BSA from 300 to 800μg with coupling efficiency decreased. These results showed that the magnetic nanoparticles after phase transfer can be used to the immobilization of biological molecule and could be potentially applied in down-steam application in the biomedical field.