Poly(aniline) nanowires in sol-gel coated ITO: A pH-responsive substrate for planar supported lipid bilayers

Chenhao Ge, Kristina S. Orosz, Neal R. Armstrong, S. Scott Saavedra

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Facilitated ion transport across an artificial lipid bilayer coupled to a solid substrate is a function common to several types of bioelectronic devices based on supported membranes, including biomimetic fuel cells and ion channel biosensors. Described here is fabrication of a pH-sensitive transducer composed of a porous sol-gel layer derivatized with poly(aniline) (PANI) nanowires grown from an underlying planar indium-tin oxide (ITO) electrode. The upper sol-gel surface is hydrophilic, smooth, and compatible with deposition of a planar supported lipid bilayer (PSLB) formed via vesicle fusion. Conducting tip AFM was used to show that the PANI wires are connected to the ITO, which convert this electrode into a potentiometric pH sensor. The response to changes in the pH of the buffer contacting the PANI nanowire/sol-gel/ITO electrode is blocked by the very low ion permeability of the overlying fluid PSLB. The feasibility of using this assembly to monitor facilitated proton transport across the PSLB was demonstrated by doping the membrane with lipophilic ionophores that respond to a transmembrane pH gradient, which produced an apparent proton permeability several orders of magnitude greater than values measured for undoped lipid bilayers.

Original languageEnglish (US)
Pages (from-to)2677-2685
Number of pages9
JournalACS Applied Materials and Interfaces
Volume3
Issue number7
DOIs
StatePublished - Jul 27 2011

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Keywords

  • conductive tip AFM
  • indium-tin oxide
  • ionophore
  • lipid bilayer
  • nanowires
  • poly(aniline)
  • proton transport
  • sol-gel

ASJC Scopus subject areas

  • Materials Science(all)

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