Multilayers of a globular protein and a weak polyacid: Role of polyacid ionization in growth and decomposition in salt solutions

Academic Article

Abstract

  • Thin films obtained from a layer-by-layer deposition of a weak polycarboxylic acid and a positively charged globular protein were studied by in situ ATR-FTIR. The system was chicken egg lysozyme (Lys), bovine pancrease ribonuclease A (RNase), or bovine γ-globulin (IgG) self-assembled with polycarboxylic acids. When the pH value was lowered below a critical point, the growth of films and their tolerance to decomposition by added sodium chloride improved dramatically. Stabilization of protein/polyacid films in salt solutions at lower pH values occurred due to the onset of nonelectrostatic interactions to intermolecular binding within protein/polyacid multilayers, and was controlled by polyacid ionization within the film rather than the pH of the external solution. A fractional ionization of polyacid in the pH-stabilization region was lower with protein-containing films than for polyacid/linear polycation films, reflecting hindrance of the inter-association of protonated carboxylic groups by protein globules. Practical ramifications of the pH-stabilization effect might extend to areas of biotechnology and biomaterials. © 2005 American Chemical Society.
  • Published In

  • Biomacromolecules  Journal
  • Digital Object Identifier (doi)

    Author List

  • Izumrudov VA; Kharlampieva E; Sukhishvili SA
  • Start Page

  • 1782
  • End Page

  • 1788
  • Volume

  • 6
  • Issue

  • 3