Please use this identifier to cite or link to this item
|title: ||Effects of magnetite nanoparticles on the thermorheological properties of carrageenan hydrogels|
|authors: ||Daniel-da-Silva, Ana L.|
Lopes-da-Silva, Jose A.
Goodfellow, Brian J.
Gil, Ana M.
|keywords: ||Thermoreversible sol–gel transition|
|issue date: ||Aug-2008|
|abstract: ||The influence of magnetite (Fe3O4) nanoparticles on the rheological properties of κ-, ι- and λ-
carrageenan gels has been investigated. Small amplitude oscillatory shear measurements were performed
to study the effect of the presence of Fe3O4 nanoparticles with particle sizes of ca. 10 nm on the gel
properties, as a function of carrageenan type, carrageenan concentration and magnetite load. The formation
of Fe3O4 nanoparticles on the presence of biopolymer was observed to promote the gelation process
and lead to stronger gels as indicated by an increase in the gel viscoelastic moduli and of the gelation
temperature. This effect was more marked for κ-carrageenan than for ι- and λ-carrageenan and has been
proposed to depend not only on Fe3O4 concentration but also on the concentration of potassium ions.
A mechanism based on the combined effect of Fe3O4 nanoparticles and potassium ions was suggested,
involving the adsorption of potassium ions on the negatively charged surface of the Fe3O4 nanoparticles,
thus leading to an increase of the potassium ion concentration within the “carrageenan cages” containing
the magnetite. This would, therefore, promote more extensive biopolymer helical aggregation, thus
resulting in the formation of a stronger κ-carrageenan gel in the presence of Fe3O4, as observed. Since
ι- and λ-carrageenan gels are known to be less sensitive to potassium ions concentration, the effect of
precipitating Fe3O4 within these biopolymers is reduced.|
|publisher version/DOI: ||dx.doi.org/10.1016/j.jcis.2008.04.051|
|source: ||Journal Of Colloid And Interface Science|
|appears in collections||DQ - Artigos|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.