Charge reversal by salt-induced aggregation in aqueous lactoferrin solutions

Mela, Ioanna, Aumaitre, Elodie, Williamson, Ann-Marie and Yakubov, Gleb E. (2010) Charge reversal by salt-induced aggregation in aqueous lactoferrin solutions. Colloids and Surfaces B: Biointerfaces, 78 1: 53-60. doi:10.1016/j.colsurfb.2010.02.011

Author Mela, Ioanna
Aumaitre, Elodie
Williamson, Ann-Marie
Yakubov, Gleb E.
Title Charge reversal by salt-induced aggregation in aqueous lactoferrin solutions
Journal name Colloids and Surfaces B: Biointerfaces   Check publisher's open access policy
ISSN 0927-7765
Publication date 2010
Year available 2010
Sub-type Article (original research)
DOI 10.1016/j.colsurfb.2010.02.011
Open Access Status
Volume 78
Issue 1
Start page 53
End page 60
Total pages 8
Place of publication Amsterdam, The Netherlands
Publisher Elsevier BV
Language eng
Abstract We have observed salt-induced aggregation in lactoferrin solutions using dynamic light scattering (DLS). Aggregates start to form once the ionic strength exceeds 10. mM, and are of opposite charge to their monomer building blocks. The presence of aggregates was monitored by electrophoretic measurements, in which the change of isoelectric point in lactoferrin solutions was observed and found to depend on the concentration of background electrolyte. Complimentary atomic force microscopy (AFM) imaging of adsorbed lactoferrin films demonstrated that for negatively charged surfaces (mica, glass) the topography of the adsorbed film remains invariant to changes in ionic strength, whilst for positively charged surfaces (chitosan coated mica) we observed a salt-induced transition in deposited architecture, with ∼100. nm aggregates being deposited together with monomers for ionic strengths in excess of 10. mM. The size of aggregates observed with AFM is consistent with those observed using DLS. These results suggest that negatively charged lactoferrin aggregates adsorb only onto positively charged surfaces, whereas isolated lactoferrin molecules are sufficiently amphiphilic and adsorb at surfaces of either charge, although without producing a charge inversion effect.
Keyword Atomic force microscopy
Dynamic light scattering
Electrophoretic mobility
Gastric mucin
Iron bioavailability
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemical Engineering Publications
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Created: Thu, 14 May 2015, 16:31:23 EST by Gleb Yakubov on behalf of School of Chemical Engineering