The present invention describes the preparation of hydrogels (or 3D matrices) obtainable from aqueous solutions of mixtures of acid polysaccharides and derivatives of basic polysaccharides, such as oligosaccharide derivatives of chitosan. Said solutions are suitably gelled with either chemical or physical gelling agents with the aim of encapsulating either cells, isolated or in multicellular associations, or pharmacologically active molecules, in solution or suspension, for use in the biomedical and pharmaceutical field.
