Enhanced Stability and Fluidity in Droplet on Hydrogel Bilayers for Measuring Membrane Protein Diffusion

• Published in: Nano letters Vol. 7; no. 12; pp. 3875 - 3878
• Main Authors: Thompson, James R, Heron, Andrew J, Santoso, Yusdi, Wallace, Mark I
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-12-2007
• Subjects: Biological and medical sciences; Condensed matter: structure, mechanical and thermal properties; Diffusion; Diffusion in nanoscale solids; Diffusion in solids; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General aspects; Hemolysin Proteins - chemistry; Hydrogels - chemistry; Instrumentation. Materials. Reagents. Research laboratory organization; Kinetics; Lipid Bilayers - chemistry; Membrane Proteins - chemistry; Microscopy, Fluorescence; Models, Biological; Physics; Transport properties of condensed matter (nonelectronic); Hemolysins; Lipids; Droplets; Hydrogel; Diffusion; Precursor; Lipid bilayers; Fluorescence microscopy; Monomers; Bilayers; Membrane proteins
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl071943y

We form artificial lipid bilayers suitable for single-molecule fluorescence microscopy by contacting an aqueous droplet with a hydrogel support immersed in a solution of lipid in oil. Our results show that droplet on hydrogel bilayers (DHBs) have high lipid mobilities, similar to those observed in unsupported lipid bilayers. DHBs are also stable over a period of several weeks. We examine membrane protein diffusion in these bilayers and report a decreased lateral mobility of the heptameric β-barrel pore-forming toxin α-hemolysin versus that of its monomeric precursor. These results corroborate previous models of the α-hemolysin insertion mechanism where the monomer binds to the lipid bilayer without insertion.