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Scientific article
English

Conformational Changes and Aggregation of Alginic Acid as Determined By Fluorescence Correlation Spectroscopy

Published inBiomacromolecules, vol. 8, no. 1, p. 106-112
Publication date2007
Abstract

Insight into the conformations and aggregation of alginic acid was gained by measuring its diffusion coefficient at very dilute concentrations using fluorescence correlation spectroscopy. Both the pH and ionic strength (I) had an important influence on the diffusion coefficient of the polysaccharide. For pH, three effects were isolated:  (i) below pH 4, the charge density decreased causing increased aggregation; (ii) between pH 4 and 8, a molecular expansion was observed with increasing pH, whereas (iii) above pH 8 some dissociation of the polymer was observed. Increasing I from 0.001 to 0.1 M resulted in a ca. 20% increase in the diffusion coefficient. By coupling these measurements to molar mass determinations obtained by size exclusion chromatography and monomer size estimations determined from ab initio calculations, it was possible to determine the radii of gyration via de Gennes renormalization theory. From diffusion coefficients and radii of gyration obtained as a function of ionic strength, persistence lengths (total, electrostatic, and intrinsic) were calculated from the Benoit−Doty relationship.

Keywords
  • Conformational Changes
  • Aggregation
  • Alginic Acid
  • Fluorescence Correlation Spectroscopy
  • Ionic Strength
Funding
  • Swiss National Science Foundation - Microstructures and dynamic processes in aquatic systems
  • Autre - Engineering Research Council of Canada
Citation (ISO format)
AVALTRONI, Fabrice François et al. Conformational Changes and Aggregation of Alginic Acid as Determined By Fluorescence Correlation Spectroscopy. In: Biomacromolecules, 2007, vol. 8, n° 1, p. 106–112. doi: 10.1021/bm060655d
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Article (Published version)
accessLevelRestricted
Identifiers
ISSN of the journal1525-7797
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