Improvement of hyaluronic acid enzymatic stability by the grafting of amino-acids

► We modified hyaluronic acid by grafting various amino acids on its carboxylic groups. ► All amino acid-HA polymers were more resistant to degradation compared to native HA. ► The HA-amino acid products were cross-linked with butanediol diglycidyl ether (BDDE). ► The increased resistance of HA-aa gels towards hyaluronidase digestion remained.