Techniques to Measure Biophysical Properties of Lipid Membranes and Lily Flowers

Abstract

Complex biophysical phenomena can be broken down into building blocks that can be probed and manipulated through experiment to expand our understanding of those phenomena. To define and characterize the building blocks, experimentalists choose techniques to measure the underlying biophysical properties that influence the phenomena. Each technique has advantages and disadvantages and may come with underlying assumptions that should be confronted in order to strengthen scientific results. In this dissertation, we will discuss two biophysical systems: phospholipid membranes and lily flowers. In the first discussion, we pare down the compositional organization of biological membranes, focusing on the utility of model membranes for isolating the independent, biophysical contributions of each constituent lipid. We evaluate an assumption that model membranes have the same composition of lipids as the stock from which they are made. Model membranes are then used to elucidate the effect of PE-lipids on micron-scale, liquid-liquid phase separation in membranes with a ternary lipid composition. In the second discussion, we shift to a much larger biophysical system and characterize rippling and blooming phenomena in lily flowers using a combination of physical, spectroscopic, and computational techniques. While our experimental results with lily flowers are motivated and inspired by previous work and simulations, we expect that our experimental results for the phase behavior of model membranes containing PE-lipids will inspire new theory and simulations.