Mucus is a bio-gel, an opaque and slimy secretion that forms a continuous ¿blanket¿ adherent to epithelial surfaces in mammalian organs (eye, nose, conductive airways, gastrointestinal tract). Mucus has a fundamental role in protecting organs exposed to external hazards and, therefore, it represents a real barrier to efficient drug delivery. Our interest lies in quantifying the diffusion of polymer drug carriers through such mucin solutions, and therefore the impact of such polymers on the structure of mucin solutions. Our SANS and NMR data has been very instructive in highlighting the relevant factors - principally electrostatics - in defining the nature of the interaction. However, a key question arises regarding whether SANS can probe the pertinent length scale. We wish to address this issue by undertaking a spin-echo SAND study to extend the length probed in the solution.