Ionic conductivity of the aqueous layer separating a lipid bilayer membrane and a glass support

Ryan J. White, Bo Zhang, Susan Daniel, John M. Tang, Eric N. Ervin, Paul S. Cremer, Henry S. White

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

The in-plane ionic conductivity of the ∼ 1-nm-thick aqueous layer separating a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer membrane and a glass support was investigated. The aqueous layer conductivity was measured by tip-dip deposition of a POPC bilayer onto the surface of a 20- to 75-μm-thick glass membrane containing a single conical-shaped nanopore and recording the current-voltage (i-V) behavior of the glass membrane nanopore/POPC bilayer structure. The steady-state current across the glass membrane passes through the nanopore (45-480 nm radius) and spreads radially outward within the aqueous layer between the glass support and bilayer. This aqueous layer corresponds to the dominant resistance of the glass membrane nanopore/POPC bilayer structure. Fluorescence recovery after photobleaching measurements using dye-labeled lipids verified that the POPC bilayer maintains a significant degree of fluidity on the glass membrane. The slopes of ohmic i-V curves yield an aqueous layer conductivity of (3 ±1) × 10 -3 Ω-1 cm-1 assuming a layer thickness of 1.0 nm. This conductivity is essentially independent of the concentration of KCl in the bulk solution ( 10-4 to 1 M) in contact with the membrane. The results indicate that the concentration and mobility of charge carriers in the aqueous layer between the glass support and bilayer are largely determined by the local structure of the glass/water/bilayer interface.

Original languageEnglish (US)
Pages (from-to)10777-10783
Number of pages7
JournalLangmuir
Volume22
Issue number25
DOIs
StatePublished - Dec 5 2006

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Fingerprint Dive into the research topics of 'Ionic conductivity of the aqueous layer separating a lipid bilayer membrane and a glass support'. Together they form a unique fingerprint.

Cite this