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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The synthesis and characterization of imprinted polymer composite membranes and use of the membranes for depleting riboflavine from beer are hereby reported. The membranes were prepared by phase inversion of a suspension of imprinted polymer particles, which had previously been shown to exhibit selective recognition of vitamin B2 in aqueous media in a solution of poly‐methylmethacrylate and polyethylenglycol in acetone. Membranes with different loads of imprinted particles were prepared and characterized by scanning electron microscopy, Fourier‐transform infrared chemical imaging and permeability measurements. Subsequently they were tested in both static and dynamic partitioning experiments concerning their ability to bind riboflavine versus other competing solutes such as lumichrome and uridine. The membranes exhibited a pronounced selectivity for riboflavine and were capable of partially depleting nearly 80% of the vitamin from beer. Meanwhile, a membrane prepared identically using nonimprinted particles resulted in a maximum removal of nearly 50%, however, with low selectivity. PRACTICAL APPLICATIONS Membranes incorporating molecularly imprinted polymer particles is a new tool for food processing allowing the traceless removal of preselected substances, e.g., flavors, spoilage agents or impurities. As suggested by the results presented in this contribution, such membranes could potentially find use in the brewing industry for selective depletion of riboflavine thus leading to enhanced beer stability.