Silane-Modified Magnetic Beads: Application to Immunoglobulin G Separation

Abstract

The magnetic poly(2-hydroxyethyl methacrylate ethylene glycol dimethacrylate) [m-poly(HEMA-EGDMA)] beads (150-250-microm diameter in spherical form) were prepared by a radical suspension polymerization technique. The pseudo-specific ligand, reactive imidazole containing 3-(2-imidazoline-1-yl)propyl (triethoxysilane) (IMEO) was selected as a silanization agent. IMEO was covalently immobilized onto the magnetic beads. IMEO-immobilized m-poly(HEMA-EGDMA) beads were used for the affinity adsorption of immunoglobulin-G (IgG) from aqueous solutions and human plasma. To evaluate the degree of IMEO attachment, the m-poly(HEMA-EGDMA) beads were subjected to Si analysis by using flame atomizer atomic absorption spectrometer, and it was estimated as 36.6 mg IMEO/g of polymer. The nonspecific IgG adsorption onto the plain m-poly(HEMA-EGDMA) beads was very low (about 0.4 mg/g). Higher adsorption values (up to 55 mg/g) were obtained when the m-poly(HEMA-EGDMA)/IMEO beads were used from both aqueous solutions and human plasma. The maximum IgG adsorption on the m-poly(HEMA-EGDMA)-IMEO beads was observed at pH 7.0. The IgG molecules could be repeatedly adsorbed and desorbed with m-poly(HEMA-EGDMA)-IMEO beads without noticeable loss in the IgG adsorption capacity. The adsorption capacity from human plasma in magnetically stabilized fluidized bed decreased drastically from 78.9 to 19.6 mg/g with the increase of the flow rate from 0.2 to 3.5 mL/min.

Surface-modification-directed controlled adsorption of serum albumin onto magnetite nanocuboids synthesized in a gel-diffusion technique

“…Due to the availability of -OH groups on surfaces, a variety of surface modifications can be done on magnetite surfaces, such as organic acids [6,7], several hydrophilic and hydrophobic polymers [8][9][10][11], and surfactants [12]. Magnetic separation technology has been widely investigated in the field of protein separation in recent years [13][14][15]. Pure magnetic particles may have the following limitations [16]: (i) they tend to form large aggregates; (ii) their original structure may be changed if they are not stable enough, resulting in the alteration of their magnetic properties; and (iii) they can undergo rapid biodegradation when they are directly exposed to the biological system.…”

pH-Sensitive Magnetic Ion Exchanger for Protein Separation

“…However, they usually contain multistage processes such as precipitation, dialysis, ultrafiltration, and chromatography, which are generally complicated, time-consuming, and expensive for large-scale production. To solve these problems, magnetic separation technology has been introduced and widely investigated in the field of protein separation in recent years, − because it can be used to selectively recover desired proteins from liquors containing biological particulates in a rapid and easy way . By now, many investigations that focused on combining magnetic particles with ion-exchange support or synthesizing magnetic ion exchangers and have achieved success to some extent. − However, because the surface electric properties of most traditional ion-exchange supports were usually unalterable or unable to reverse through the changes of pH, the supports could not be controlled to selectively adsorb and release proteins through self-transformation.…”