HA is a non-sulphated glycosaminoglycan (GAG) and is composed of repeating polymeric disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine linked by a glucuronidic β (1→3) bond.In aqueous solutions HA forms specific stable tertiary structures. Despite the simplicity in its composition, without variations in its sugar composition or without branching points, HA has a variety of physicochemical properties. HA polymers occur in a vast number of configurations and shapes, depending on their size, salt concentration, pH, and associated cations.