Preparation and characterization of magnetic alginate nanocomposites

GIANINA A. KLOSTER; DIEGO MURACA; NORMA E. MARCOVICH; MIRNA A. MOSIEWICKI

Buenos Aires

Conferencia; 6th International Conference on Science and Technology of Composite Materials; 2015

ITPN - INTECIN - INIFTA - INTEMA - INTI - ECN - Facultad de Ingeniería UBA

The synthesis of monodisperse nanostructures of iron oxide is currently of tremendous interest since they are extensively used in magnetic materials, as photocatalyst, sensors and medical applications such as hyperthermia, targeted drug delivery, magnetic resonance imaging, etc. Below 15 nm, iron oxide nanoparticles have superparamagnetic behavior. However, magnetic iron oxide particles have hydrophobic surfaces with large surface area to volume ratio. These hydrophobic interactions coupled with magnetic ones result in particle aggregation, which leads to a decrease in the magnetic properties of the agglomerated iron oxide nanoparticles respect to those of the disaggregated ones. In this sense, synthesis methods that embed nanoparticles into polymer, glass, SiO2 matrices have the added benefits of minimizing nanoparticle aggregation and forming a uniform particle dispersion and a narrow particle size distribution. In this work, sodium alginate, a natural linear polysaccharide extracted from brown algae and composed of -L-guluronic and -D-mannuronic acid residues, was selected as the biodegradable and biocompatible polymeric matrix for the preparation of magnetic films. Sodium alginate (2% wt/v) was dissolved in NaOH (0.3 mol/L) solution and immediately mixed with the corresponding volume of a 0.2 mol/L ferric salts aqueous solution (Fe2+:Fe3+ = 1:2 molar ratio) to obtain final films with 0, 2, 5, 7 and 10 wt% nanomagnetite. The magnetic nanoparticles precipitated during this step, leading to darker suspensions as higher was the iron oxide concentration. These suspensions were then casted into Petri dished and dried at 40ºC in a convective oven, resulting in brown-colored, strong and flexible films that presented magnetic behavior. Preliminary results indicate that composite films resulted at least in a coupling between magnetic properties of the particles and the elastic ones of the polymer, however, a complete characterization will be performed in order to determine is there are synergetic effects between the components of the system.