Abstract: In the present invention nanocomposite materials in form of three-dimensional structure formed by a polymeric matrix consisting of a polysaccharidic composition of neutral or anionic polysaccharides and a branched cationic polysaccharides, in which metallic nanoparticles are uniformly dispersed and stabilized, are described. Using appropriate techniques of gelification or by means of an appropriate dehydration, the nanocomposite materials are three-dimensional matrices having different shapes in hydrated form as hydrogels, or in non-hydrated form. These nanocomposite materials have a broad-spectrum of strong bactericidal activity, but do not show any cytotoxicity.