An anionic polysaccharide chosen from polysaccharides comprising carboxyl functions of formula V, said polysaccharides being monofunctionalized: - in which n represents the degree of functionalization of the carboxyl functions of the polysaccharide by an F 1 -R 1 -G-Ach sequence and is between 0.01 and 0.7, • F 1 being either an amide function or an ester function or a thioester function, • G being either an ester function or an amide function or a thioester function, • R 1 being a divalent radical composed of a chain comprising between 1 and 15 carbon atoms which is optionally branched and/or unsaturated, which optionally comprises one or more heteroatoms, such as O, N and/or S, and which optionally comprises one or more saturated, unsaturated or aromatic rings or heterocycles and resulting from the reaction of a precursor R 1 ' having at least two identical or different reactive functions chosen from the group consisting of alcohol, amine and thiol functions, • Ach being a radical which is the product of the coupling between the carboxyl function of the hydrophobic acid and at least one reactive function carried by the precursor R 1 ' of the divalent radical R 1, and, when the carboxyl function of the polysaccharide is not functionalized by F 1 -R 1 -G-Ach, then the carboxyl function or functions of the polysaccharide are cation carboxylates. - in which n represents the degree of functionalization of the carboxyl functions of the polysaccharide by an F 1 -R 1 -G-Ach sequence and is between 0.01 and 0.7, • F 1 being either an amide function or an ester function or a thioester function, • G being either an ester function or an amide function or a thioester function, • R 1 being a divalent radical composed of a chain comprising between 1 and 15 carbon atoms which is optionally branched and/or unsaturated, which optionally comprises one or more heteroatoms, such as O, N and/or S, and which optionally comprises one or more saturated, unsaturated or aromatic rings or heterocycles and resulting from the reaction of a precursor R 1 ' having at least two identical or different reactive functions chosen from the group consisting of alcohol, amine and thiol functions, • Ach being a radical which is the product of the coupling between the carboxyl function of the hydrophobic acid and at least one reactive function carried by the precursor R 1 ' of the divalent radical R 1, and, when the carboxyl function of the polysaccharide is not functionalized by F 1 -R 1 -G-Ach, then the carboxyl function or functions of the polysaccharide are cation carboxylates. • F 1 being either an amide function or an ester function or a thioester function, • G being either an ester function or an amide function or a thioester function, • R 1 being a divalent radical composed of a chain comprising between 1 and 15 carbon atoms which is optionally branched and/or unsaturated, which optionally comprises one or more heteroatoms, such as O, N and/or S, and which optionally comprises one or more saturated, unsaturated or aromatic rings or heterocycles and resulting from the reaction of a precursor R 1 ' having at least two identical or different reactive functions chosen from the group consisting of alcohol, amine and thiol functions, • Ach being a radical which is the product of the coupling between the carboxyl function of the hydrophobic acid and at least one reactive function carried by the precursor R 1 ' of the divalent radical R 1,