Tailoring the Surface Properties of Co-based Metal–Organic Frameworks for Highly Efficient and Selective Enrichment of Immunoglobulin G

The high tunability of metal–organic frameworks (MOFs) provides attractive flexibility to tailor their surface properties for practical demands. Here we report the regulation of the surface properties (hydrophilicity and charge characteristics) of Co-based MOFs by exploiting different organic building units and tailor them as efficient adsorbents for specific protein enrichment. Compared with the pristine Co-based MOF (Co-MOF) and the aminated MOF (Co-MOF-NH2), the MOF decorated with abundant hydroxyl groups (Co-MOF-OH) exhibits superior adsorption selectivity and enriched efficiency toward immunoglobulin G (IgG) in the physiological state (pH 7.4) by taking advantage of the favorable hydrogen-bonding interactions and electrostatic force between IgG and Co-MOF-OH. The enrichment factor for IgG is high, up to 97.7 for enriching IgG from the IgG/human serum albumin mixture with a mass ratio of 1:50, and circular dichroism indicates that the enrichment process poses no influence on the protein structure. Moreover, Co-MOF-OH proves its practicability in complex biological samples by the selective extraction of IgG from complex human serum samples.