A molecularly imprinted polymer (MIP) refers to a synthetic polymer with templated binding or catalytic sites. MIPs are typically prepared by conventional network polymerization in the presence of a template serving the dual role of preorganizing individual monomers and as a mold for inducing shape complementary binding sites. Removal of the template result in a MIP exhibiting antibody-like recognition behavior with nanomolar, or higher, affinities for the template or targets with template substructures. These binders are robust, resist denaturing solvents, high temperatures and can be reproducibly and cost-effectively produced. Hence, they are potentially useful as antibody substitutes in protein and glycan detection strategies. MIPs targeting protein PTMs have in this context emerged as a promising alternative to established affinity reagents. For instance, efficient amino acid side chain specific enrichment of tryptic peptides from cell lysates or complex protein digests have been demonstrated for phosphotyrosine , phosphoserine and most recently labile phosphohistidine PTMs . The design of these MIPs relies on the use of neutral urea-based host monomers with tunable affinity for oxyanions such as carboxylates and phosphates.