Magnetic nanostructured composites using alginates of different M/G ratios as polymeric matrix

International Journal of Biological Macromolecules

Volume 27, Issue 1, pp. 35 - 40, 16 March, 2000

Magnetic nanostructured composites using alginates of different M/G ratios as polymeric matrix

Authors

Francisco Llanes^a, Dominic H. Ryan^b, Robert H. Marchessault^c

^a Biomaterials Center, University of Havana, 10400 Havana, Cuba
^b Department of Physics, McGill University, Montreal, Québec, Canada H3A 2T8
^c Pulp and Paper Research Centre and Department of Chemistry, McGill University, 3420 University Street, Montreal, Québec, Canada H3A 2A7

Abstract

Alginate extracted from Sargassum fluitans and Macrocystis pyrifera with different molecular weights and mannuronic/guluronic ratios, M/G, were used as gel matrixes in order to obtain magnetic nanostructured composites. Magnetic nanocrystalline particles of iron oxides were formed inside the alginate matrix by in situ alkaline oxidation of ferrous ions. The magnetic materials obtained were subjected to several oxidative cycles and the increment in iron content was determined after each cycle. X-ray diffraction, magnetometry and Mössbauer spectroscopy were used to examine the materials. The high magnetic response, the absence of hysteresis, and the centered paramagnetic doublet in the Mössbauer spectra indicate the presence of nanocrystalline particles with a superparamagnetic behavior. X-ray diffractograms show peaks that correspond to maghemite. After the first cycle, Sargassum had four times the magnetic response of Macrocystis, which had more than twice the M/G ratio.

Keywords: Alginate, Maghemite, Magnetic nanocomposites

PII: s0141813099001154