RUI: Self-Assembled Interfaces: Protolipids, Asymmetry, and Energetics

Iona University, New Rochelle NY

Investigators

Abstract

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Sunghee Lee and her research group in the Department of Chemistry at Iona University are undertaking studies on how living cells arrange molecular components in their membranes. These boundary layers are composed of long-tailed lipid (fatty) molecules that assemble in a double layer (a bilayer) with different kinds of lipid molecules on the inner layer relative to the outer layer. This molecular difference, or asymmetry, is vital for cell function, and yet the fundamental reasons for this arrangement are not fully known. Professor Lee and her team will explore a large array of lipid compositions of cell membranes, using cell-size water droplets that self-arrange into asymmetric bilayers, and microscopically examine the resulting physical, chemical, and mechanical properties of these cell-mimics. The goal of the project is to determine how the differing shapes and sizes of individual lipid molecules can impact cell-membrane mechanical strength, leakiness, and stability, which determine the functions and the life cycle of living cells. The project has the potential to provide insights that aid in the design of soft matter systems and functional materials, and also contribute to better understanding of biologically relevant materials. The scientific broader impacts of the proposed work relate to potential longer term implications of these studies for the production of biosensors, diagnostics, and drug screening platforms. This project will also employ research methods that will help train the next generation of globally-competitive scientists with hypothesis-driven interdisciplinary research, and is expected to include participation from members of underrepresented groups. Outreach activities are planned to extend the public engagement with this research by involving middle/high school students and teachers at minority serving institutions. Under this award, Professor Sunghee Lee and her group will impose increasing spontaneous curvature upon symmetric and asymmetric planar lipid bilayers and ascertain changes in the driving force for bilayer formation, to develop a direct experimental transducer for curvature elastic stress energy. Models of symmetric and asymmetric bilayers comprising lipids of negative curvature will be examined for their effect upon the thermodynamic driving force for bilayer formation. To quantify the effects of lipid shape, the Lee group will acquire water transport parameters across the bilayer, determine bilayer stability parameters, ascertain electrical properties, use vibrational spectroscopy for determination of acyl chain order, and perform thermotropic analyses of lipid dispersions. Dissemination of the technology will include working with collaborators to apply the techniques of asymmetric droplet interface bilayers for studies of protein function. 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.