Synthesis of new type of Au-magnetic nanocomposite and application for protein separation thereof

We present a different strategy for synthesizing the Au-γ-Fe(2)O(3) bifunctional nanoparticle by using a larger (50 nm) Au nanoparticle as the core surrounded by smaller (10 nm) γ-Fe(2)O(3) nanoparticles. The synthesis of the composite nanoparticles is quite facile based on a simple redox process whereby Fe(2+) is used to reduce Au(3+). The morphology and composition of the product is measured by transmission electron microscopy, X-ray powder diffraction and UV–vis spectroscopy. We demonstrate the utility of these as-prepared Au-γ-Fe(2)O(3) nanoparticles by showing they can be used to separate proteins in solution. For example, bovine serum is efficiently removed from an aqueous solution with the simple addition of the NPs and application of a small magnet. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis is performed to evaluate the fidelity and efficiency of the protein separation procedure.