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 . the particular antibacterial properties associated with metallic particle nano - scale and the presence of biological signals on the polymeric chains along with the lack of cytotoxicity may be exploited in developing new - generation biomaterials provided with antimicrobial properties and for many other applications in biomedical , pharmaceutical and food field .