Highly sensitive detection of processes occurring inside nanoporous anodic alumina templates: a waveguide optical study

K. H. A. Lau, L. S. Tan, K. Tamada, M. S. Sander, W. Knoll

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Abstract

We have applied nanoporous anodic alumina films as planar optical waveguides and studied changes in the effective dielectric constants of these thin films due to various processes occurring in the pores. We demonstrate the potential of the porous anodic alumina waveguide for high sensitivity (bio-) chemical sensing with bovine serum albumin adsorption and desorption at various pH values, with subangstrom sensitivity in the effective thickness of protein adsorbed. We also monitored pore widening (alumina dissolution) with subangstrom sensitivity, which is conceptually the reverse of detecting conformal film deposition on pore surfaces. Furthermore, we monitored the exchange of pore-filling media between phosphate buffer solution and ethanol, which produces qualitatively the same response as complete pore filling with other materials by various deposition techniques. Thus porous anodic alumina films may be employed simultaneously as deposition templates and as highly sensitive detectors of processes within the pores.
Original languageEnglish
Pages (from-to)10812-10818
Number of pages7
JournalJournal of Physical Chemistry B
Volume108
Issue number30
Early online date23 Jun 2004
DOIs
Publication statusPublished - 2004

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Keywords

  • desorption
  • bovine serum-albumin
  • self-assembled monolayers
  • solid-liquid interfaces
  • protein adsorption
  • lipid-bilayers
  • thin-films
  • surface membranes
  • kinetics

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