Hydrogel comprising a cross-linked and silylated polysaccharide and process for obtaining same

A process for preparing a hydrogel comprising the following steps:

• a) providing at least a polysaccharide or a salt thereof;
• b) cross-linking the polysaccharide in the presence of 0.05 to 10 mol % of at least a cross-linking agent, or a salt thereof, per 1 mole of repeat units of the polysaccharide, the cross-linking agent comprising at least two functional Z groups, which are identical or different, selected from the group consisting of isocyanate, amino, epoxide, carboxyl,
• N-succinimidyloxycarbonyl, N-sulfosuccinimidyloxycarbonyl, halogenocarbonyl, isothiocyanate, vinyl, formyl, hydroxyl, sulfhydryl, hydrazino, acylhydrazino, aminoxy, carbodiimide, and an acid anhydride residue;
• c) functionalizing the polysaccharide with at least a molecule of formula Chem. I:
• or a salt thereof
• in which:
• T represents an isocyanate, amino, epoxide, carboxyl, N-succinimidyloxycarbonyl, N-sulfosuccinimidyloxycarbonyl, halogenocarbonyl, isothiocyanate, vinyl, formyl, hydroxyl, sulfhydryl, hydrazino, acylhydrazino, aminoxy, carbodiimide group, or an acid anhydride residue;
• A represents a chemical bond or a spacer group;
• R5 and R6, which are identical or different, represent a hydrogen atom;
• a halogen atom;
• an —OR4 group with R4 representing a hydrogen atom, an aryl group or an aliphatic hydrocarbon group including from 1 to 6 carbon atoms;
• an aryl;
• or an aliphatic hydrocarbon group including from 1 to 6 carbon atoms optionally substituted by one or more group(s) selected from the group consisting of a halogen atom, an aryl and a hydroxyl;
• R10 represents a hydrogen atom, an aryl group or an aliphatic hydrocarbon group including from 1 to 6 carbon atoms;
• d) sol-gel reacting at least a part of the Si—OR10 groups and optionally at least a part of the SiOR4 groups when they are present;
• in which step b) is carried out before, or concomitantly with step c), or step b) is carried out consecutively to steps c) and d).