Analytical and Bioanalytical Chemistry

, Volume 389, Issue 7, pp 2115–2124

Photonic crystal sensor for organophosphate nerve agents utilizing the organophosphorus hydrolase enzyme

  • Jeremy P. Walker
  • Kyle W. Kimble
  • Sanford A. Asher
Original Paper

DOI: 10.1007/s00216-007-1599-y

Cite this article as:
Walker, J.P., Kimble, K.W. & Asher, S.A. Anal Bioanal Chem (2007) 389: 2115. doi:10.1007/s00216-007-1599-y

Abstract

We developed an intelligent polymerized crystalline colloidal array (IPCCA) photonic crystal sensing material which reversibly senses the organophosphate compound methyl paraoxon at micromolar concentrations in aqueous solutions. A periodic array of colloidal particles is embedded in a poly-2-hydroxyethylacrylate hydrogel. The particle lattice spacing is such that the array Bragg-diffracts visible light. We utilize a bimodular sensing approach in which the enzyme organophosphorus hydrolase (OPH) catalyzes the hydrolysis of methyl paraoxon at basic pH, producing p-nitrophenolate, dimethylphosphate, and two protons. The protons lower the pH and create a steady-state pH gradient. Protonation of the phenolates attached to the hydrogel makes the free energy of mixing of the hydrogel less favorable, which causes the hydrogel to shrink. The IPCCA’s lattice constant decreases, which blueshifts the diffracted light. The magnitude of the steady-state diffraction blueshift is proportional to the concentration of methyl paraoxon. The current detection limit is 0.2 μmol methyl paraoxon per liter.

Keywords

Sensor Pesticide Organophosphate Organophosphorus hydrolase Enzyme Polymerized Crystalline Colloidal Array (PCCA) 

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Jeremy P. Walker
    • 1
  • Kyle W. Kimble
    • 1
  • Sanford A. Asher
    • 1
  1. 1.Department of Chemistry, Chevron Science CenterUniversity of PittsburghPittsburghUSA