Figure 1.

Overview of mucus and mucus selectivity. (A) Mucins contain disordered, heavily glycosylated, polyanionic domains interspersed with globular hydrophobic domains. These polymers are chemically and physically cross-linked to form a polymer network. (B) Particles larger than the mesh size of mucus (magenta) have hindered passage, while particles smaller than the mesh size may pass through more freely. (C) Binding to polymeric mucin components slows diffusion. D) Polyvalent binding strongly hinders diffusion, even if each individual binding interaction is weak. E) Spatial arrangement of charge impacts the diffusion of particles in mucus.