Functionalized polyoxometalate microspheres ensure selective adsorption of phosphoproteins and glycoproteins

Abstract

Lacunary polyoxometalate (POM), [PW₉O₃₄]⁹⁻, grafts with a boronic acid group attached via an organosilane bridge assemble into microspheres, PW₉–Si–APBA. The oxygen-rich and hydrophilic surface of POM facilitates the binding of phosphate groups in phosphoproteins and glycans in glycoproteins. While the metal–oxo in POM provides π–π interactions with the phosphate groups of phosphoproteins, the boronic acid group specifically binds to glycoproteins via the cis-diols of glycans. Therefore, these multi-driving forces ensure the selective adsorption of phosphoproteins and glycoproteins by PW₉–Si–APBA microspheres in biological sample matrixes, even in the presence of very high protein abundance, i.e., BSA, at mass ratio of β-ca/IgG/OVA/BSA = 1 : 1 : 1 : 200.