Process for the simultaneous substitution and crosslinking of a polysaccharide via its hydroxyl functional groups

A process for obtaining a substituted and crosslinked polysaccharide, comprising:

• performing simultaneous substitution and crosslinking of a polysaccharide in an aqueous reaction medium by reacting at least one precursor of a substituent and a crosslinking agent with hydroxyl functional groups of the polysaccharide, in the presence of a basic or acidic catalyst at a concentration between 3.16×10−7 and 0.32 mol/L, and at a temperature of less than 60° C.;
• and
• obtaining the substituted and crosslinked polysaccharide in gel form after the simultaneous substitution and crosslinking of the polysaccharide is performed,
• wherein:
• the polysaccharide is chosen from the group consisting of hyaluronic acid and salts thereof, chitosan, cellulose, and derivatives thereof;
• the crosslinking agent is chosen from the group consisting of ethylene glycol diglycidyl ether, butanediol diglycidyl ether, polyglycerol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, a bisepoxy or a polyepoxy, a dialkyl sulfone, divinyl sulfone, formaldehyde, and glutaraldehyde;
• the precursor of the substituent comprises a single reactive functional group capable of forming a bond with a hydroxyl functional group of the polysaccharide, the reactive functional group being chosen from the group consisting of substituted or unsubstituted vinyl, substituted or unsubstituted epoxide, substituted or unsubstituted allyl, ketone, aldehyde, thiocyanate, halide, isocyanate, halosilicon, nitrile and sultone functional groups;
• and
• substitution is not carried out via the crosslinking agent.