Geometry-Dependent Nonequilibrium Steady-State Diffusion and Adsorption of Lipid Vesicles in Micropillar Arrays
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Univ. of Tennessee, Knoxville, TN (United States)
- Eastern Tennessee State Univ., Johnson City, TN (United States)
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.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC05-00OR22725; DE‐AC05‐00OR22725
- OSTI ID:
- 1546529
- Alternate ID(s):
- OSTI ID: 1501712
- Journal Information:
- Advanced Materials Interfaces, Vol. 6, Issue 9; ISSN 2196-7350
- Publisher:
- Wiley-VCHCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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