CAREER: Solute and particle transport in granular microgels

Hydrogels are soft, sponge-like materials that contain large amounts of water. When a hydrogel is broken down into small particles, it forms a microgel. A microgel is a grain like cluster of soft, slippery particles. Cells that are placed in microgels grow, organize, and divide, much like they would in their natural environment. As a result, microgels have significant potential in cancer research for studying tumor behavior and rapidly testing potential anticancer agents outside the body. However, microgels dramatically limit the transport of oxygen and nutrients to the cells, hindering long-term cell studies. Using a combination of experimental and computer modeling, this CAREER project will investigate mechanisms of molecular and particle transport in microgels. The results will improve understanding of transport in soft porous materials and inform the development of engineered cell culture environments that more accurately replicate physiological exchanges. The research project will engage high school, undergraduate, and graduate students, thereby contributing to the development of a skilled workforce trained to engineer systems that advance biotechnology and national health. In addition, the project will integrate outreach initiatives, ranging from activities that encourage scientific curiosity in children to educational programs for high school students. This award will elucidate transport phenomena in multiscale poroelastic substrates using jammed suspensions of sub-millimeter hydrogel particles, or granular microgels, as a model system. Poroelastic materials are commonly described as a solid matrix that deforms elastically, with void spaces filled with a viscous fluid. This description does not directly apply to granular microgels, as the hydrogel particles are themselves poroelastic. To address this knowledge gap, the project will use novel methods to synthesize hydrogel particles with tunable properties. Three fundamental questions will be addressed through a combination of millifluidic experiments and numerical simulations: (1) How do the bulk and surface properties of hydrogel particles affect the fluid flow and the transport of solutes and particles through granular microgels? (2) How does pressure influence flow and transport? (3) Can granular microgel be engineered to enhance transport and support cell growth and assembly? The results will contribute to predictive models and inform biomedical applications. Cell culture environments with tunable transport properties could support fundamental studies on cell aggregates and advance patient specific medicine. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.