Synthesis of magnetic silica nanospheres with metal ligands and application in affinity separation of proteins

Magnetic silica nanospheres with immobilized metal ligands were prepared for the separation of proteins. First, silica-coated magnetite nanospheres were prepared by the deposition of silica onto ultrafine (about 8 nm) magnetite particles via controlled hydrolysis of sodium silicate. Then through reaction of iminodiacetic acid (IDA) with 3-glycidoxypropyltrimethoxysilane (GLYMO) and immobilization of them onto the above magnetic silica nanospheres, novel magnetic affinity adsorbents with IDA chelating groups were obtained. Charged with Zn2+, the magnetic nanospheres were applied to separate a model protein mixture of bovine hemoglobin (BHb) and bovine serum albumin (BSA). They could be separated completely and showed low non-specific adsorption. The morphology and magnetic properties of magnetic silica nanospheres were investigated by TEM and VSM. The nanospheres have an average size of 200 nm and possess superparamagnetic characteristics. These magnetic silica nanospheres with metal ligands can be used efficiently in protein affinity separation and purification.