Poly(guanidinium ionic liquid)s particles as affinity platform for highly selective enrichment of phosphopeptides

The preparation of materials capable of the selective enrichment of phosphorylated peptides is important to phosphoproteome study. Herein, a new poly(guanidinium ionic liquid)s material was prepared using a polymerizable guanidinium ionic liquids as the functional monomer. A large number of guanidinium groups on the surface of the materials may interact with the phosphorylated peptides by a non-covalent bond such as a hydrogen bond and ionic bond. The feasibility of the resulting materials for the enrichment of phosphopeptides was investigated further using standard proteins, protein mixture and nonfat milk as samples. The resulting materials showed excellent enrichment property for phosphopeptides such as high selectivity (phosphopeptides/non-phosphopeptides at a molar ratio of 1:1000) and extremely high detection sensitivity (4.0 × 10−11 M). The excellent practical utility of the resulting materials for phosphopeptides enrichment was also demonstrated by enriching the phosphopeptides from tryptic digest of nonfat milk.