Effective adsorption and separation of lysozyme with PAA-modified Fe3O4@silica core/shell microspheres.

Submicron-size Fe(3)O(4)@silica core/shell microspheres were prepared by sol-gel method. Through coating inert silica shell and adjusting the thickness, the dispersibility of magnetic microspheres in water was greatly improved. The resultant Fe(3)O(4)@silica microspheres with controllable saturation magnetization between 34.3 emu/g and 47.3 emu/g were superparamagnetic. All as-prepared magnetic composite microspheres possessed fleetly magnetic responsivity. The PAA-modified Fe(3)O(4)@silica microspheres were used for selective adsorption and separation of lysozyme, and the experimental results showed that the maximum binding capacity is about 127 mg/g. After surface modification of Fe(3)O(4)@silica with polyacrylic acid (PAA) flexible chains, the binding capacity of Fe(3)O(4)@silica-g-PAA microspheres for lysozyme were 22 times as much as that of pure Fe(3)O(4)@silica microspheres at the same pH condition.