Synthesis,Characterization And Application Of Fe₃O₄ And TiO₂ Nanoparticles

Nanotechnology is one of the three high technologies in the twenty-one century. Nanotechnology has been developing fast since 1980s. The research of inorganic nanopaticles is one of the hottest aspects in nanotechnology. Fe3O4 nanoparticles and TiO2 nanoparticles were investigated in this paper. The effects of different kinds of synthesis condition on the crystal, shape, sizes, chemical and physical properties were studied in detail, and some useful results were obtained.Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe2+ and Fe3+ in an ammonia solution, and its size was about 36 nm measured by Atomic Force Microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR conformed the forming of Fe-O-C bond. The immobilization of trypsin directly on Fe3O4 magnetic nanoparticles as well as via L-dopa and dopamine spacer molecules using glutaraldehyde as coupling agent was investigated. The sizes and magnetic properties of the three kinds of magnetic nanoparticles with or without trypsin had no significant change. The spacer molecule on magnetic nanoparticles could improve the activity and the storage stability of bound trypsin greatly by increasing the flexibility of enzyme and changing the microenvironment around the enzyme on nanoparticles surface compared to magnetic nanoparticles without being modified.Three different TiO2 nanoparticles were prepared by hydrothermal method, Sol-Gel method and homogeneous precipitation method respectively. Their crystal were rutile (contained some other crystal nanoparticles), rutile and anatase measured by XRD respectively. Their sizes were about 30nm, 10~100nm and 1nm measured by TEM respectively. Their isoelectric points were about 5.2, 6.1 and 3.0 respectively. The above results indicate that the TiO2 nanoparticles prepared by hydrothermal have regular shapes, good dispersion properties and small sizes. The TiO2 nanoparticles prepared by sol-gel were pure, and had irregular shapes and sizes, and easily to aggregate. The nanoparticles prepared by homogeneous precipitation had the minimal size, but aggregate very easily. The nanoparticles prepared by homogeneous precipitation could absorb ultraviolet more broadly and strongly than the other two.