Specific Isolation of Glycoproteins with Mesoporous Zirconia-Polyoxometalate Hybrid

A novel mesoporous zirconia-polyoxometalate ZrO₂ -P₈ W₄₈ hybrid was prepared using a surfactant-assisted solvent evaporation technique. The acid-base reaction between the Zr-OH groups of zirconium oxides and P₈ W₄₈ was followed by self-assembly with an amphiphilic triblock copolymer as template to obtain a polyoxometalate-based hybrid. The ZrO₂ -P₈ W₄₈ hybrid was characterized by Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetric assay (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray diffraction (XRD), and nitrogen sorption/desorption. Owing to the multiple hydrogen-bonding interactions between the P₈ W₄₈ moiety and the hydroxyl groups of glycoproteins, the ZrO₂ -P₈ W₄₈ hybrid exhibited highly selective isolation of glycoproteins from complex matrices that included various non-glycoproteins. The retained glycoproteins could be readily recovered using a 0.01 mol L^-1 cetane trimethyl ammonium bromide (CTAB) solution as stripping reagent, with recovery rates of 92, 100, 100, 100, and 74% for the five target glycoproteins, Ovalbumin (Ova), conalbumin (ConA), immunoglobulin G from human serum (IgG), γ-globulin from bovine milk (γ-Glo), and horseradish peroxidase (HRP), respectively. The ZrO₂ -P₈ W₄₈ hybrid was successfully applied to the isolation of glycoproteins from egg white and human serum samples, as confirmed by SDS-PAGE and LC-MS/MS assays.