Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis (1). In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc (2). Magnetic Fe3O4 nanoparticles were prepared by coprecipitating Fe2+ (FeSO4·7H2O) and Fe3+ (FeCl3·6H2O) ions in ammonia solution (3). To prepare reactive magnetic supports APES was added to solution of Nano Fe3O4 in Ethanol. The APES-bound magnetic nanoparticles were thus obtained. Thereafter, glutaraldehyde, as a coupling reagent, was added to the precipitates of APES-coated magnetic nanoparticles, the glutaraldehyde activated particles were separated by magnetic decantation. Then an aliquot of lipase (lipase from Asperjillus Niger) solution (0.1 M phosphate buffer, pH 7.0) was mixed with the above activated carriers. After completion of the reaction, the unbounded enzyme was removed under a magnetic field, and the precipitates were recovered and washed carefully with phosphate buffer (0.1 M phosphate buffer, pH 7.0) for several times, and then verified by transmission electron microscopy (TEM), scanning electron microscope (SEM), IR spectroscopy, X-ray diffraction (XRD) and a vibrating sample magnetometer (VSM). Then used it in synthesis of heterocyclic compounds.
