Preparation, Characterization, and Enzyme Immobilization Capacities of Superparamagnetic Silica/Iron Oxide Nanocomposites with Mesostructured Porosity

We present a method to produce superparamagnetic iron oxide/silica nanocomposites that have a large BET surface area, a high pore volume, and at least one pore size population centered at around or larger than 10 nm. By means of this methodology, which is based on nanocasting techniques, we are able to not only prepare mesoporous iron oxide/silica nanocomposites with adequate pore sizes and magnetic properties for enzyme immobilization but also explore various phenomena associated with the characteristics of the magnetic mesoporous matrixes. Magnetic nanocomposites that have a ordered mesostructured porosity, a high BET surface area, and a high pore volume display a better distribution of their magnetic components and superior magnetic properties than magnetic nanocomposites with a disordered mesostructured porosity and low BET surface area. The applicability of this kind of composites for the immobilization and magnetic separation of biomolecules has been clearly demonstrated in the case of lysozyme.