Fabrication and characterization of rigid magnetic monodisperse microspheres for protein adsorption

This article describes the fabrication of a rigid magnetic monodisperse bead (M-PGMA-TRI, 4.92 microm) with polyglycidyl methacrylate (PGMA) cross-linked by trimethylolpropane trimethacrylate (TRI). This was realized by adding a proper amount (2%, w/w) of TRI after 3 h of the dispersion-polymerization reaction with the monomer of GMA. The mono-sized microspheres were further processed to introduce magnetic granules by sulfonation and penetration-deposition approaches. The monodisperse bead (M-PGMA) without TRI addition was also fabricated for comparison. The morphology, size and magnetic characteristics of the microspheres were extensively characterized. The M-PGMA-TRI microspheres were nonporous, of smooth surface and superparamagnetic with a saturation magnetization of 13.0 emicro/g. Recycled use of the material for protein adsorption exhibited stability of the magnetic properties of the M-PGMA-TRI, as compared to the significant loss of the saturation magnetization of the M-PGMA. The chemical stability of the M-PGMA-TRI was also confirmed by examining its protein adsorption and magnetic properties after incubation in various solutions such as acidic buffer (pH 2.2) for 24 h. The adsorption capacity of gamma-globulin reached 287.2 mg/g and kept stable in the repeated adsorption/desorption/regeneration cycles. The results indicated that the introduction of 2% TRI was promising for producing rigid magnetic mono-sized microspheres for protein adsorption.