CONICET | Buscador de Institutos y Recursos Humanos

The challenge of carbohydrate recognition has been taken by different groups in the last three decades motorized by the fundamental role of saccharides and their conjugates in major biological processes. The dynamic covalent reaction between boronic acids and cis-diols is a convenient and highly biocompatible strategy to develop fluorescent probes towards glicoconjugates [1], an elusive target in the molecular probes field. With the goal of providing novel labeling agents able to detect glycoproteins in biological media, we introduce a fluorescent molecular probe named Cy-Bx able to detect glycoproteins, especially mucins, with high sensitivity and with a turn-on response along with a large Stokes shift (>130 nm), in the biologically active window (700-900 nm). The probe contains an aminotricarbocyanine as the fluorescent reporter with a linked benzoboroxole as the recognition unit, which reacts through the boronic hemiester residue with the cis-diols of the analyte. Cy-Bx showed a fluorogenic response to the presence of model glycoproteins in cuvette with negligible non-specific binding. By means of a simple labeling protocol, the probe shows high specificity for mucin by imaging granules in airway epithelial Calu-3 cells, demonstrated by co-localization analysis in comparison to a specific antibody. We were also able to discriminate different morphologies of the granules in our cellular model. The new benzoboroxole fluorescent derivative gathers together key properties to meet high rated molecular probes: specificity, excellent solubility in water and off-on near infrared emission. The probe we provide is expected to be an excellent tool for imaging intracellular mucin to evaluate mucus related diseases as well as a sensing strategy towards glycosylated structures with a high potential for theranostics approaches in biological samples.

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