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Early detection of cancer is essential for successful treatment and improvement in patient prognosis. Deregulation of post-translational modifications (PTMs) of proteins, especially phosphorylation, is present in many types of cancer. Therefore, the development of materials for the rapid sensing of low abundant phosphorylated peptides in biological samples can be of great therapeutic value. In this work, we have synthesised fluorescent molecularly imprinted polymers (fMIPs) for the detection of the phosphorylated tyrosine epitope of ZAP70, a cancer biomarker. The polymers were grafted as nanometer-thin shells from functionalised submicron-sized silica particles using a reversible addition-fragmentation chain-transfer (RAFT) polymerisation. Employing the combination of fluorescent urea and intrinsically cationic bis-imidazolium receptor cross-linkers, we have developed fluorescent sensory particles, showing an imprinting factor (IF) of 5.0. The imprinted polymer can successfully distinguish between phosphorylated and non-phosphorylated tripeptides, reaching lower micromolar sensitivity in organic solvents and specifically capture unprotected peptide complements in a neutral buffer. Additionally, we have shown the importance of assessing the influence of counterions present in the MIP system on the imprinting process and final material performance. The potential drawbacks of using epitopes with protective groups, which can co-imprint with targeted functionality, are also discussed. [ABSTRACT FROM AUTHOR]

We describe a facile method to prepare water-compatible molecularly imprinted polymer nanogels (MIP NGs) as synthetic antibodies against target glycans. Three different phenylboronic acid (PBA) derivatives were explored as monomers for the synthesis of MIP NGs targeting either α2,6- or α2,3-sialyllactose, taken as oversimplified models of cancer-related sT and sTn antigens. Starting from commercially available 3-acrylamidophenylboronic acid, also its 2-substituted isomer and the 5-acrylamido-2-hydroxymethyl cyclic PBA monoester derivative were initially evaluated by NMR studies. Then, a small library of MIP NGs imprinted with the α2,6-linked template was synthesized and tested by mobility shift Affinity Capillary Electrophoresis (msACE), to rapidly assess an affinity ranking. Finally, the best monomer 2-acrylamido PBA was selected for the synthesis of polymers targeting both sialyllactoses. The resulting MIP NGs display an affinity constant≈10 6  M -1 and selectivity towards imprinted glycans. This general procedure could be applied to any non-modified carbohydrate template possessing a reducing end., (© 2024 Wiley-VCH GmbH.)

Aberrant sialic acid expression is one of the key indicators of pathological processes. This acidic saccharide is overexpressed in tumor cells and is a potent biomarker. Development of specific capture tools for various sialylated targets is an important step for early cancer diagnosis. However, sialic acid recognition by synthetic hosts is often complicated due to the competition for the anion binding by their counterions, such as Na + and K + . Here we report on the design of a sialic acid receptor via simultaneous recognition of both the anion and cation of the target analyte. The polymeric receptor was produced using neutral (thio)urea and crown ether based monomers for simultaneous complexation of sialic acid's carboxylate group and its countercation. Thiourea and urea based functional monomers were tested both in solution by 1 H NMR titration and in a polymer matrix system for their ability to complex the sodium salt of sialic acid alone and in the presence of crown ether. Combination of both orthogonally acting monomers resulted in higher affinities for the template in organic solvent media. The imprinted polymers displayed enhanced sialic acid recognition driven to a significant extent by the addition of the macrocyclic cation host. The effect of various counterions and solvent systems on the binding affinities is reported. Binding of K + , Na + and NH 4 + salts of sialic acid exceeded the uptake of bulky lipophilic salts. Polymers imprinted with sialic or glucuronic acids displayed a preference for their corresponding templates and showed a promising enrichment of sialylated peptides from the tryptic digest of glycoprotein bovine fetuin., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)