Mucus is a viscoelastic gel present on various moist surfaces of human body including gastrointestinal tract, eyes, respiratory system, bladder and vagina. Administration of drugs via mucosal membranes offers a number of advantages as it can be used as an alternative to injections and sometimes gives an opportunity to deliver medication directly to the target organ. However, the mucus gel often acts as a barrier for successful drug delivery; it can trap drug molecules before they are able to reach surface cells and achieve therapeutic effects. The aim of our research is to develop nanoparticles capable of crossing mucosal membranes efficiently. We will use neutron scattering to probe the structure of these nanoparticles to understand how their structural features could affect their diffusivity through mucosal membranes.