Monodispersed magnetite/silica composite microspheres: Preparation and application for plasmid DNA purification

This paper describes a new method for preparation of superparamagnetic magnetite/silica composite microspheres by modified miniemulsion polymerization. The reaction parameters on shape, size and uniformity of the nanomicrospheres were studied. Through changing the dosage of iron oxide, the composite microspheres with different magnetite content from 10wt% to 30wt% could be prepared, and the response to magnetic field is tunable depending on the magnetite loading. Under the optimized condition, the prepared composite microspheres have the character of monodispersity and quick magnetic response. This characteristic is critical for the application in biomolecular separations. The separation experiment for plasmid DNA showed that the composite microspheres possess stronger magnetic response compared with commercialized reagent. (C) 2008 Elsevier B.V. All rights reserved.