Synthesis And Property Research Of Amino-Magnetic Polymer Microspheres

Magnetic microspheres are the combination of inorganic magnetic nanoparticles and organic polymer, which are magnetic and have specific structures. Functionalization on the surface of the magnetic microspheres can make the microspheres much easier to conjugate with avidin and antibody(or antigen), etc. Thus functionalized microspheres can be applied in various aspects in biotechnology.In this study, magnetic nanoparticles were prepared by co-precipitation, and then the microspheres were prepared by microemulsion polymerization. Surface coating modification method was used to cover the microspheres with silica, and in the meantime functionlizing the microspheres with -NH2 groups. Optical microscopy and Scanning Electron Microscopy(SEM) indicate that the magnetic microspheres have spherical shape with the size of 1-3um. Fourier Transform Infrared Spectrometer(FTIR) and X-ray fluorescence(XRF) specifies the covalent bond of the microspheres and the containing elements. Thermal Gravity Analysis(TGA) results show the Fe3O4 content is 30%, and as to the microspheres which have been covered with silica, the content of silica is 1.5351%. Vibrating Sample Magnetometer is used to measure the magnetic properties, which shows the saturation magnetization is 5emu/g, and the residual magnetization and coercivity are very little. The microspheres can respond quickly under a magnetic field; it can be separated from the microspheres suspension water within 30s. Conductometric titration analyze the amount of–NH2 on the microspheres, and it can at most reach 3.2mmol/g. Fluorescence microscope is used to observe the microspheres with avidin/antibody, the results show that all microspheres can successfully conjugate with biomolecular.