Defining structure–function relationships of mucins & mucus through synthetic glycopolymer design

From coral to humans, mucus is essential for the protection, lubrication, and hydration of cells. Despite advances in network theory and polymer synthesis, how to mimic mucus and understand its critical functions remains mystifying. Our group previously disclosed that synthetic glycopolymers could mimic mucin, the primary constituent of mucus. The key to recapitulating essential features of mucin was generating an extended polymer backbone. We sought to explore the polymer attributes that influence their mucin-mimetic ability, including molecular weight, polymer backbone, sugar identity, and crosslinking motifs. Evaluation of the synthetic mucins’ morphology and cholera toxin inhibition provided an initial screen to correlate structure to function. Using chemical synthesis, we have produced a collection of mucin-mimetic glycopolymers so that mimics bearing all terminal glycans present in native mucins could be evaluated. New protocols established to assess polymer–protein binding, formerly limited to small molecule–protein binding, confirmed the terminal glycan identity is determinant of binding affinity. Finally, crosslinking of synthetic mucins was achieved through disulfide, ionic, or covalent bonds and the materials were compared through rheology to assign which crosslinking strategy best mimicked native mucus.