DYNAMICS, STABILITY, AND THERMODYNAMICS OF DEFORMABLE BIOLOGICAL MEMBRANES INTERACTING WITH NEWTONIAN AND VISCOELASTIC FLUIDS

Biological membranes are ubiquitous for the regular functioning of our human body. If we view our body from a micro perspective, we are made up of objects that are derformable in nature. This could be a blood vessel or a cell membrane containing nutrients. Fluid-structure interactions lie at the heart of these phenomena. Moreover, when one inspects these biological membranes, they would come across a plethora of complex macromolecules that make up such systems. An example of such a system is the lipid bilayer that surrounds most of the cells in our body. These bilayers are made up of phsopholipid molecules interspersed with cholesterol and other molecules. Due to the nature of the cholesterol molecules and steric effects, they prefer one type of lipid molecule over the other thereby leading to phase separation on the cell membrane surface. This phase separation has been understood experimentally in systems involving no flow or other complex dynamics. This phase separation is the basis of the formation of lipid rafts which is key in the transport of nutrients across such membranes. Analyzing these systems is of importance from a fundamental as well as an applied perspective in order to tune therapeutics as well as processing techniques. In this thesis, we try to evaluate deformable biological aspects from multiple lenses – fluid dynamics, mechanics, and thermodynamics.