Magnetic Silica-Coated Sub-Microspheres with Immobilized Metal Ions for the Selective Removal of Bovine Hemoglobin from Bovine Blood

Magnetic silica-coated magnetite (Fe3O4) sub-microspheres with immobilized metal-affinity ligands are prepared for protein adsorption. First, magnetite sub-microspheres were synthesized by a hydrothermal method. Then silica was coated on the surface of Fe3O4 particles using a sol gel method to obtain magnetic silica sub-microspheres with core-shell morphology. Next, the trichloro(4-chloromethyl-phenyl) silane was immobilized on them, reacted with iminodiacetic acid (IDA), and charged with Cu2+. The obtained magnetic silica sub-microspheres with immobilized Cu2+ were applied for the absorption of bovine hemoglobin (BHb) and the removal of BHb from bovine blood. The size, morphology, and magnetic properties of the resulting magnetic micro(nano) spheres were investigated by using scanning microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and a vibrating sample magnetometer (VSM). The measurements showed that the magnetic sub-micro-spheres are spherical in shape, very uniform in size with a core-shell, and are almost superparamagnetic. The saturation magnetization of silica-coated magnetite (Fe3O4) sub-microspheres reached about 33 emu g(-1). Protein adsorption results showed that the sub-microspheres had a high adsorption capacity for BHb (418.6 mg g(-1)), low nonspecific adsorption, and good removal of BHb from bovine blood. This opens a novel route for future applications in removing abundant proteins in proteomic analysis.