Boronic Acid-Functionalized Magnetic Metal–Organic Frameworks via a Dual-Ligand Strategy for Highly Efficient Enrichment of Phosphopeptides and Glycopeptides

To date, abundant strategies and affinity materials are proposed to enrich phosphopeptides and glycopeptides from biological systems. However, few affinity materials can meet the demand for enriching both phosphopeptides and glycopeptides with an integrated single material. In this work, a novel magnetic metal–organic framework nanocomposite with Zr4+ ions as metal unit as well as terephthalic acid (PTA) and 1,4-phenylenebisboronic acid (denoted as PBA) as dual organic ligands was designed and fabricated for highly efficient enrichment of both phosphopeptides and glycopeptides. It is worth mentioning that Zr4+ ions and PBA were well assembled into the MOF coating via the dual-ligand strategy to achieve both phosphopeptide and glycopeptide enrichment by the Zr–O clusters based on metal oxide affinity chromatography (MOAC) and abundant boronic acid groups based on boronic acid affinity chromatography (BAAC) methods. The quick magnetic response performance and high surface area endowed the affinity material outstanding ability for phosphopeptide and glycopeptide enrichment in the model protein mixtures (β-casein, human IgG, and bovine serum albumin). Furthermore, the nanocomposites exhibited specific enrichment capacity in complex biological samples (rat brain and rat liver), revealing the great potential for the identification and analysis of trace phosphopeptides and glycopeptides in biological samples.