Role of Electrostatic Interactions in Two-Dimensional Self-Assembly of Tobacco Mosaic Viruses on Cationic Lipid Monolayers
Abstract
We explore two-dimensional self-assembly of tobacco mosaic viruses (TMVs) on a substrate-supported, fluid lipid monolayer by manipulating the electrostatic interactions, with specific focus on the effects of the cationic lipid concentration in the monolayer and the presence of Ca2+ ions in the surrounding bulk solution. The TMV assemblies were characterized by grazing-incidence X-ray scattering and atomic force microscopy, and the inter-particle interaction quantified through X-ray scattering data analysis. In the absence of Ca2+ ions, we found that higher charge densities on the lipid monolayer led to poorer in-plane order, which may be attributed to faster adsorption kinetics, due to the surface potential that increases with charge density. At the same time, higher lipid-charge densities also resulted in weaker repulsion between TMVs, due to partial screening of Coulomb repulsion by mobile cationic lipids in the monolayer. The lipid-charge dependence was diminished with increasing concentration of Ca2+ ions, which also led to tighter packing of TMVs. The results indicate that Ca2+ ions strengthen the screening of Coulomb repulsion between TMVs and consequently enhance the role of attractive forces. Control experiments involving Na+ ions suggest that the attractive inter-TMV interaction has contributions from both the van der Waals force and the counter-ion-induced attraction that depends on ion valence.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 21, 2011
- Accession Number
- ADA580318
Entities
People
- Antonio Checco
- Lin Yang
- Masafumi Fukuto
- Qian Wang
- Suntao Wang
- Zhongwei Niu
Organizations
- Brookhaven National Laboratory