title: Nanostructure of polysaccharide complexes.
abstract: The interaction of gum arabic (GA) with chitosan (Ch) of different degree of deacetylation was studied by turbidity measurements, dynamic light scattering and atomic force microscopy. The structure of the complexes was found to be directly related to the charge density of chitosan molecules. Gum arabic and chitosan with a degree of deacetylation of 75% form soluble complexes with a loosely globular structure of about 250 nm, at weight ratios up to 1.2, if the concentrations are kept low (total biopolymer concentration up to 0.06%). If chitosan has a higher charge density (degree of deacetylation of 93%), colloidal particles are formed, independently of the polymer concentration or ratio. At low concentrations and GA/Ch ratios of 1 or 1.2, the particles have diameters of 200-250 nm. The formation of soluble complexes is attributed to a chitosan lower charge density and the presence of non-charged monomers, which prevent the efficient self-assembly of the macromolecules.
authors.affiliation: LEPAE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal.
authors.forename: Sílvia
authors.initials: S
authors.lastname: Coelho
authors.forename: Susana
authors.initials: S
authors.lastname: Moreno-Flores
authors.forename: José L
authors.initials: JL
authors.lastname: Toca-Herrera
authors.forename: Manuel A N
authors.initials: MA
authors.lastname: Coelho
authors.forename: M Carmo
authors.initials: MC
authors.lastname: Pereira
authors.forename: Sandra
authors.initials: S
authors.lastname: Rocha
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D006170:Gum Arabic / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D006170:Gum Arabic; D048271:Chitosan