Biological membranes and synthetic vesicles (small membrane-bound sacs) often contain regions that behave like thin, elastic solids embedded within otherwise fluid surfaces. Predicting how these solid patches deform is a major scientific challenge because two competing forces are at work: fluid membrane regions naturally want to adopt smoothly curved shapes, while solid domains, like a sheet of paper, resist stretching and tearing. Since fluid and solid portions are forced coexist in one single, close quasi-spherical surface, a geometric conflict arises, known as frustration, leading to surprisingly complex compromised structures.
In this study, UMass Amherst researchers used advanced computational modeling to explore how a circular solid domain behaves when attached to a closed membrane vesicle. Their simulations revealed a rich sequence of shape transitions as the vesicle inflates. Depending on membrane tension and material properties, the solid region can roll, fold, crumple, wrinkle, or ultimately smooth into a cap-like shape. The work identifies the key physical mechanisms that control these transitions and shows strong agreement with experimentally observed lipid vesicles.
The findings provide new insight into how complex structures emerge in biological membranes and soft materials. Beyond explaining direct experimental observations, made by UMass collaborators in the Polymer Science and Engineering Department, the results offer design principles for engineered vesicles, stimuli-responsive materials, and membrane-based systems whose shape and function can be controlled through geometry and mechanics.
UMass research computing enabled the large-scale finite-element simulations needed to map these intricate shape behaviors and connect theory with experiment, via iterative and close-loop feedbacks.
Jeon, G., Prempeh, A. N. A., Santore, M. M., & Grason, G. M. (2026), Frustrated Shapes of Solid Domains in Fluid Membrane Vesicles: From Rolls and Folds to Crumples and Wrinkles, New Journal of Physics, doi: 10.1088/1367-2630/aea4e
