Molecular characterization of mucus binding

Mucus coats all wet epithelial surfaces of the body. Binding of small molecules to mucus has an important role in human health, as it may affect the diffusivity and activity of drugs and toxins that act in a mucosal environment. Despite the importance of mucus-small molecule binding, there is a lack of data revealing the precise physicochemical features of small molecules that lead to mucus binding. We developed a novel equilibrium dialysis assay to measure the binding of small molecules to mucin and other mucus components at unprecedented throughput, and combined this assay with a small molecule microarray to identify a novel mucin binding motif. Furthermore, we showed that for molecules with this motif, binding to mucins and the mucus-associated biopolymers DNA and alginate is modulated by differences in hydrophobicity and charge. Finally, we showed that molecules without the motif exhibited different trends from molecules with the motif, suggesting a complex dependence of mucin binding on molecular physicochemical properties.