Chemical Engineering Seminar

Biological compartments such as organelles, cells, organs, and organisms are all surrounded by selective barriers, which control the exchange of material between them and their environment. These barriers typically consist of a lipid bilayer that is externally coated by a protein-polysaccharide hydrogel. The selective permeability properties of the lipid bilayer have been extensively studied in the last century. In contrast, we know little about the structure and dynamics of biological hydrogels and how their properties allow them to act as selective barriers that permit passage of certain objects but reject others. One important and understudied hydrogel is mucus, the clear, slimy gel that coats wet surfaces in the body of all animals. Mucus barriers have critical roles in health and disease and changes in their structure or properties can result in diseases ranging from dental cavity formation, cystic fibrosis, viral and parasitic infections, to some forms of infertility caused by a failure of the sperm to migrate through mucus in the female genital tract. I will present our work on basic mechanisms by which mucus barriers exclude, or allow passage of different molecules and pathogens, and the mechanisms pathogens have evolved to penetrate mucus barriers. We hope to provide the foundation for a theoretical framework that captures general principles governing selectivity in mucus, and likely other biological hydrogels such as nuclear pores, and bacterial biofilms. Our work may also be the basis for the reconstitution of synthetic gels that mimic the basic selective properties of biological gel-based barriers.