Magnetic Fe₃O₄@mTiO₂-AIPA Microspheres for Separation of Phosphoproteins and Non-phosphoproteins

Abstract

A novel phosphoprotein separation material was developed, which is constructed by a magnetic mesoporous Fe₃O₄@TiO₂ (Fe₃O₄@mTiO₂) microsphere and a 5-aminoisophthalic acid (AIPA) monolayer that provides additional binding sites toward phosphate groups. The results of characteristic experiments demonstrated that Fe₃O₄@mTiO₂-AIPA had good dispersability, high magnetic susceptibility, and satisfactory grafting ratio of AIPA, ascribed to the large specific surface area of the inorganic substrate. Taking advantages of these features, Fe₃O₄@mTiO₂-AIPA was successfully utilized to separate α-casein (a typical phosphoprotein) and bovine serum albumin (BSA, a typical non-phosphoprotein) from their mixtures (molar ratio = 1:2). Through adjusting pH and polarity of solutions, the BSA and α-casein were respectively enriched in washing fraction and elution fraction. This result displays the good potential of Fe₃O₄@mTiO₂-AIPA for application in phosphoprotein enrichment.

Keywords

magnetic microsphere / phosphoprotein / separation / α-casein