Cross-linked polysaccharides

A product having application in the medical, pharmaceutical and dermo-cosmetic fields comprising a cross-linked polysaccharide in which cross-linking occurs only through amide bonds between carboxy groups of the polysaccharide and amino groups of a polyamine in which the polysaccharide is selected from the group consisting of hyaluronic acids, carboxymethyldextran, carboxymethylcellulose, carboxymethylstarch, alginic acids, cellulose acid, N-carboxymethyl or butyl glucans or chitosans, heparins with different molecular weights, optionally desulfated and succinylated, dermatan sulfates, chodroitin sulfates and heparin sulfates obtained by (a) reacting the carboxy groups of a polysaccharide in an aqueous aprotic solvent using a suitable carboxy activating agent, (b) reacting the carboxy activated polysaccharide with a polyamine selected from the group having the formula R1—NH-A-NH—R2 herein R1 and R2, which may be the same or different, are hydrogen, C1-C6 alkyl, phenyl, or benzyl groups;

• A is a C2-C10 alkylene chain;
• a polyoxylene chain of the formula [(CH2)n]m wherein n is 2 or 3 and m is an interger from 2 to 10, a C5-C7 cycloalkyl group or an aryl or heterocyclic group and (c) recovering the resultant cross-linked polsaccharide.