Facile synthesis of high-magnetization γ-Fe2O3/alginate/silica microspheres for isolation of plasma DNA

A novel process combining emulsification with sol–gel method is described to synthesize γ-Fe2O3/alginate/silica microspheres. The synthesis procedure consists of two steps: (1) synthesis of magnetic alginate microspheres via an emulsification technique; (2) in situ synthesis of magnetic silica microspheres by the hydrolysis of TEOS in the presence of ammonia solution. The as-synthesized composite microspheres with a typical average diameter of 4.4 μm were spherical and superparamagnetic. Moreover, they contained up to 31.7 wt% maghemite with a saturation magnetization of 15.1 emu g−1. The application of these magnetic microspheres as adsorbents for isolation of plasma DNA has also been studied.