Hyaluronic acid (HA) or hyaluronan is a natural glycosaminoglycan copolymer of D-glucuronic acid andN-acetyl-D-glucosamine. Hyaluronic acid can be found inarticular cartilageand the synovial fluid. It is degraded by cell-secreted hyaluronidase. Its molecular weight varies and can go up to 1-2 million Da.

Hyaluronan can be prepared from a variety of animal tissues therefore it possesses a risk of animal-derived pathogens.

Figure 1: Structure of hyaluronic acid.

Hyaluronic acid (HA) has been used successfully ashydrogelsbut it is difficult to tailor the mechanical properties of this naturalscaffoldaccording to tissue requirements.