Progress in the development of nano-sized hybrid therapeutics and nano-sized drug delivery systems - "nanomedicines" - over the last decade has been remarkable. One key requirement is the knowledge of how polymers interact with the many biological barriers that they meet en route to the site of action. The mucus layer adherent to epithelial surfaces is a formidable barrier and offers considerable protection against inhaled materials, be they drug delivery related or environmental challenges (e.g. soot). This experiment is designed to probe the solution structure of mucin, a model for mucus, and how this is modulated by the presence of particles intended to represent both environmental and drug delivery related materials.