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Gel--sol transition in kappa-carrageenan systems: microviscosity of hydrophobic microdomains, dynamic rheology and molecular conformation.

Authors
  • Hugerth, A
  • Nilsson, S
  • Sundelöf, L O
Type
Published Article
Journal
International Journal of Biological Macromolecules
Publisher
Elsevier
Publication Date
Oct 01, 1999
Volume
26
Issue
1
Pages
69–76
Identifiers
PMID: 10520958
Source
Medline
License
Unknown

Abstract

The effect of gel-sol transition in kappa-carrageenan systems on the microviscosity of hydrophobic microdomains, as well as its relation to macroscopic rheology and molecular conformation, was studied in kappa-carrageenan systems. The microdomains were probed by 1,3-di(-1-pyrenyl)propane (P3P) for which the excimer intensity (Ie) provides relative measures of the microviscosity in the immediate probe surroundings. In particular the applicability of P3P to monitor the gel--sol transition was proved, the results showing a dramatic decrease in microviscosity in the vicinity of the transition point. The corresponding changes in rheological properties and carrageenan conformation were investigated by dynamic viscometry (DV) and optical rotation (OR), respectively. The temperature of onset of the transition as indicated by the microviscosity data (T0) was found to correlate well with the OR and DV-results. The application of microviscosity and OR-measurements allowed an estimation of the helical content at T0 to be determined. P3P-data indicate a microenvironment viscosity for the probe sites in the kappa-carrageenan system comparable to that found in SDS micelles.

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