Hyperphosphorylation at tyrosine is commonly observed in tumor proteomes and, hence, specific phosphoproteins or phosphopeptides could serve as markers useful for cancer diagnostics and therapeutics. The analysis of such targets is, however, a challenging task, because of their commonly low abundance and the lack of robust and effective preconcentration techniques. As a robust alternative to the commonly used immunoaffinity techniques that rely on phosphotyrosine(pTyr)-specific antibodies, we have developed an epitope-imprinting strategy that leads to a synthetic pTyr-selective imprinted polymer receptor. The binding site incorporates two monourea ligands placed by preorganization around a pTyr dianion template. The tight binding site displayed good binding affinities for the pTyr template, in the range of that observed for corresponding antibodies, and a clear preference for pTyr over phosphoserine (pSer). In further analogy to the antibodies, the imprinted polymer was capable of capturing short tyrosine phosphorylated peptides in the presence of an excess of their non-phosphorylated counterparts or peptides phosphorylated at serine.

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A set of polymers has been imprinted with (−)-ephedrine at six different temperatures, ranging from −30 to +80 °C. Polymer affinity and specificity were observed to be strongly dependent on the polymerization temperature. The experimental results suggest that the polymer is able to “memorize” the temperature used in the polymerization process in a manner similar to previously documented MIP “memory” effects for the template and polymerization solvent. In a study of the effect of temperature on retention and selectivity in HPLC (using the MIP as a column packing), a clear gradient change in the Van't Hoff plots was observed at 20−30 °C. This indicates a transition in binding mechanism from exothermic at higher temperatures to endothermic at lower temperatures. These results, supported by the evidence of template-induced MIP swelling, are interpreted in terms of desolvation and conformational changes in the polymers induced by the interaction with the template.