High interaction alginate-hyaluronate associations by hyaluronate deacetylation for the preparation of efficient biomaterials

The paper presents fundamental investigations of alginate-hyaluronate assoc iation with significant polymer interactions for preparation of efficient b iomaterials. For this purpose, acetamide functions of hyaluronate were part ly cleaved by hydrazine at high temperature, yielding amino groups accessib le to carboxylic functions of the alginate chain. Alginate-hyaluronate asso ciation was studied both in dissolved state by rheological measurements and CD, and in the form of gel slabs prepared after calcium diffusion. Appreci able interaction between carboxylic groups of alginate and the released ami no groups of hyaluronate was put into evidence by enhanced values of the vi scosity of mixed solutions, and by assessment of the properties of the gel formed: moderate deacetylation allowed gels of improved hardness and viscos ity. Nevertheless, high deacetylation was observed to hinder the gel format ion by Ca2+ complexation of alginate, by the significant competition of COO H-NH2 association. Interaction between alginate and modified hyaluronate re sults in regular gel structure, with small cavities. (C) 2000 John Wiley & Sons, Inc.