Abstract
Directing the geometry of membranes is a goal shared by many disciplines. From designing drug delivery systems in bioengineering to understanding how membranes regulate their size and shape in physics, the study of structural transitions of membranes offers many potential insights into membrane assembly. However, biological membranes operate on small length and time scales that make it difficult to examine the physics behind biomembrane configuration using standard microscopy techniques. Here, we present an experimental model system consisting of colloidal membranes that can be used to study the universal physics driving membrane restructuring. These colloidal membranes are much larger than lipid membranes, making them easily accessible to standard microscopy techniques, such as confocal microscopy. Colloidal membranes are assembled from rod-shaped filamentous viruses through the depletion interaction. The preferred membrane configuration can be promoted by tuning the physical parameters of the filamentous viruses, such as length and chirality, through biomolecular techniques, as well as altering the environment surrounding the membranes. Primarily, we use the system to examine the universal physics governing vesicle formation, in which the membrane transitions from a two-dimensional flat sheet to a three-dimensional closed hollow shell. We find that vesicle formation in the colloidal membrane system depends on the thickness of the membrane, which is set by the virus length. Moreover, we record the transition via confocal microscopy, giving us a direct look at vesicle formation. Additionally, we study how heterogeneity affects in-plane membrane organization. Length asymmetry between two rod populations leads to the formation of domains within membranes, indicating that constituent length is an important physical characteristic in determining membrane configuration. Finally, we investigate transitions from flat sheets to one-dimensional twisted ribbons. We study the link between membrane constituent chirality and overall ribbon structure. Through this research, we find insights into the physics driving membrane reconfiguration and how the physical properties of membrane constituents affect membrane structure.