Bilayer Membranes and Cell-free Systems
The container: Phospholipid vesicles, or liposomes, have traditionally been used to model cell membranes, but are limited in mechanical strength and synthetic flexibility. In order to create synthetic membranes with a diverse range of physical and chemical properties, it has become important to expand the composition of model membranes to include other amphiphilic molecules, like diblock copolymers. We will work with a combination of biological and synthetic materials to construct responsive vesicle membranes.
The brain/factory: Cell-free systems consist of molecular machinery extracted from biological cells. They include components such as ribosomes, polymerases, nucleotide triphosphates, amino acids, among more. Together with genes, that provide genetically encoded instructions, cell-free systems can be used to synthesize RNA, DNA, and proteins and execute biological programs. When encapsulated inside bilayer membranes, cell-free systems can confer new functions to the membrane. Likewise, encapsulation of cell-free systems in a bilayer membrane can provide cell-free systems both protection and the ability to function in new environments.
Advances in the fields of synthetic biology and biomaterials have brought us closer to the goal of designing artificial cells and cellular mimetic structures capable of complex biomanufacturing, biosensing, and communication. We are especially interested in developing material systems that can mimic the biosensing and biomanufacturing capabilities of cells. Using biological parts, such as lipids and cell free expression systems, as well as synthetic parts, such as diblock copolymers and optical dyes, we are building cellular mimetic systems that can sense and report environmental analytes and environmental physical changes (ex. mechanical force, temperature, light) and that can synthesize useful products.
A self-assembled lipid bilayer forms the structural backbone of the cell membrane. This structure has a variety of physical properties that we are increasingly finding play a critical role in controlling the activities of embedded membrane proteins. These properties, like elasticity, rigidity, fluidity, hydrophobic thickness, among more, are thought to indirectly control protein behavior through long range physical interactions. We are developing technologies to measure the physical properties of bilayer membranes and are studying how mechanical properties of the membrane influence cellular processes like membrane protein folding and membrane protein activity. Our ultimate goal is to understand why cells change their composition as a function of cell type, cell organelle, and/or in response to environmental stimuli and what effect these composition changes have on the physical properties of cell membranes. Our work will provide new insight into the physical role of bilayer membranes in regulating membrane protein activities to complement ongoing studies that are investigating the biochemical role of membrane lipids on protein function.
We use a variety of tools and techniques to build and characterize membrane-based materials including microscopy, microfluidic techniques, quantitative fluorescence measurements, micropipette aspiration, microcontact printing, cell free expression, molecular biology, and bacterial and mammalian cell culture.