Abstract
Micro- and nanofabricated sample environments are useful tools for characterizing diffusion in confined aqueous environments. The steady-state diffusion and adsorption of unilamellar lipid vesicles in arrays of hydrophilic micropillars is investigated. Gradients in the coverage of fluorescently labeled, pillar-supported lipid films, formed from vesicle fusion, are determined from 3D z-stack images using confocal microscopy. The gradients are the result of preferential adsorption of vesicles near the tops of the pillars, which progressively deplete them from solution as they diffuse toward the base of the array. However, the increased propensity for vesicle adsorption near the pillar tops compared to the confined spaces between pillars results in the formation of confluent supported lipid bilayers at the pillar tops that resist the adsorption of additional vesicles while leaving the pillar surfaces below available for binding. This results in a reduction in the numbers of depleted vesicles compared to what one would anticipate based on diffusive fluxes. The resulting inhomogeneous spatial profiles of lipid structures on the pillars are the result of the system being maintained in a dissipative, nonequilibrium steady state during incubation of the pillar arrays in the vesicle solution, which is ultimately quenched by rinsing away the unbound, freely diffusing vesicles.
| Original language | English |
|---|---|
| Article number | 1900054 |
| Journal | Advanced Materials Interfaces |
| Volume | 6 |
| Issue number | 9 |
| DOIs | |
| State | Published - May 9 2019 |
Funding
Micropillar fabrication and fluorescent imaging and F.L., B.R.S., and C.P.C. were partially supported by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy. S.M.A. was supported by a Joint Directed Research and Development award from the UT-ORNL Science Alliance. J.K. was supported through the Scientific User Facilities Division of the Department of Energy (DOE) Office of Science, sponsored by the Basic Energy Sciences (BES) Program, under Contract No. DE-AC05-00OR22725. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This manuscript was authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the U.S. Government purposes.
Keywords
- adsorption
- diffusion
- microfabrication
- supported lipid bilayers
- vesicles
