ИСТИНА

The materials with magnetically adjustable pool of properties are of great importance because of great potential of their use for biomedical applications. From one hand the magnetism of nanoparticles determine their applications as: 1) contrast agents in magnetic resonance imaging studies; 2) compositions for hyperthermia treatment of lesions in the body, and 3) the magnetic component of compositions for targeted drug delivery. From another hand the polymer matrix of the composite materials must provide stabilization of nanoparticles by preventing theiraggregation and adhesion, solubility in physiological environments. In this report we present polymer composites of well defined maghemite nanoparticles and biocompatible anionic polysaccharide, sodium alginate cross-linked by Ca2+-ions.The proposed method of synthesis allows one to obtain water-soluble magnetic materials with controlled content of inorganic phase. Using this approach well defined maghemite nanoparticles with a narrow size distribution are formed. One of the major advantages of the proposed method is normal conditions of the synthesis. The role of crosslinked alginate macromolecules matrix is to restrict the growth and prevent the aggregation of forming magnetic nanoparticles. The average size of the resulted nanoparticles inclusions were 11 nm. The crystallography data has confirmed the maghemite structure of iron oxide nanoparticles. It was shown that the inorganic particles were bound to the polymer matrix by electrostatic interaction and by formation of coordination complexes. Magnetic properties of the obtained nanocomposites (saturation magnetization, residual magnetization, coercive force) were shown to depend on the maghemite content. Being dissolved in water nanocomposites formed aggregation-stable dispersions that were sensitive to the action of an external magnetic field. Stability against aggregation was ensured by overall negative surface charge of particles in the nanocomposite.