Magnetic cucurbit[6]uril-based hypercrosslinked polymers for efficient enrichment of ubiquitin

The design and preparation of magnetic cucurbit[6]uril hypercrosslinked with polymers are described. The materials have a large specific surface, abundant mesopores and cavities, and display superparamagnetism. They were applied to the enrichment of ubiquitinated peptides from standard protein digests. Following desorption with 0.15% TFA, the peptides were quantified by MALDI-TOF MS. The method has a detection limit of 2 fmol·μL^-1 and a mass ratio selectivity of 1:5000 as shown for ubiquitin and bovine serum albumin. The materials enable selective capture of ubiquitinated peptides from genuine samples comprising of oyster mushroom and human serum. This demonstrates their potential for the analysis of low-level ubiquitin in complex samples. Graphical abstract Schematic presentation for the synthesis of magnetic cucurbit[6]urils hypercrosslinked polymers (MagCB[6]-HCPs).