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

A novel phosphoprotein separation material was developed, which is constructed by a magnetic mesoporous Fe 3 O 4 @TiO 2 (Fe 3 O 4 @mTiO 2 ) microsphere and a 5-aminoisophthalic acid (AIPA) monolayer that provides additional binding sites toward phosphate groups. The results of characteristic experiments demonstrated that Fe 3 O 4 @mTiO 2 -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, Fe 3 O 4 @mTiO 2 -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 Fe 3 O 4 @mTiO 2 -AIPA for application in phosphoprotein enrichment.