Probing and modeling of transport properties of hydrogels

Biological hydrogels such as mucus form natural barriers for infectious agents and play important roles in regulating the exchange of molecules and particles between and within cells. Understanding the barrier properties and role of individual hydrogel components on the function of the barrier requires systematic measurements of the transport of particles (e.g., proteins, viruses, bacteria) into and within biological hydrogels. In this project, we will develop a new combined experimental/theoretical approach involving confocal microscopy, fluorescence correlation spectroscopy (FCS), and single particle tracking (SPT) to extract from the diffusion of particles through hydrogels the spatially dependent diffusivity profiles and, at the same time, the free-energy profiles of different types of particles in complex and inhomogeneous hydrogel materials. Only the combined knowledge of these two position-dependent material properties will allow for the development of multi-scale models that accurately describe the passive and active transport of biologically relevant particles through biological hydrogels. By systematic variation of particle size (ranging from the nm- to the μm-scale) and hydrogel design (e.g., chemical architecture, mesh size, presence of functional side groups etc.) it will be possible to elucidate the contribution of the individual hydrogel components on the generated barrier functionality.