Giant unilamellar vesicles (GUVs) are cell-sized compartments that can be assembled from amphiphilic lipid molecules in aqueous environments. The increasing interest in the use of cell-mimicking systems for therapeutics and drug delivery requires techniques that can enable the production of large numbers of GUVs at low costs. Previously, we proposed the budding and merging (BNM) model to show that the formation of GUVs on cylindrical nanofibers of cellulose was spontaneous versus flat surfaces, resulting in high GUV yields. Here, we investigate the effect of changing the surface concentration of zwitterionic lipid DOPC on the yield of GUVs assembled on cellulose nanofibers. We find that both yields and sizes of the GUVs peak at an optimal surface concentration of 17 nmol/cm<sup>2</sup>. We explain the results using the BNM model, which predicts the spontaneity of budding due to the geometry of the fiber up to a certain critical concentration, beyond which bud formation is no longer spontaneous. We use a Poisson distribution to simulate the distribution of bilayers on fibers with varying mean values to account for the variations in nominal surface concentration.  The number of buds that form spontaneously was determined using the energy required for the budding of bilayers adopting a cylindrical configuration. Only bilayers with radii below a critical radius were allowed to bud. The GUV yield and size distributions simulated from the distribution of nanobuds showed similar peaked behavior as the experimental results. It is therefore critical to control the amount of lipid deposited on the surface, to maximize yields and obtain populations of GUVs with the largest diameters.

Effect of surface concentration on the mechanism of GUV assembly

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.