An improved method to prepare hyaluronic acid and type II collagen composite matrices

An improved method to prepare hyaluronic acid (HyA) and type II collagen composite matrices was developed. HyA and type II collagen formed polyion complex (PIC) in aqueous solution due to their opposite electrostatic charges. Therefore, optimal conditions at which PIC was not formed between HyA and type II collagen were determined in order to directly crosslink using a water-soluble carbodiimide [WSC; 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride]. HyA-collagen composite matrices were successfully obtained using WSC in the presence of 0.4M NaCl, which was found the optimal concentration to suppress PIC formation. Fourier transformed infrared spectra of the obtained matrices showed ester bond formation, indicating that the crosslinking reaction between HyA molecules, HyA and collagen molecules, and collagen molecules proceeded. The swelling ratio of a HyA-collagen composite matrix depended on the WSC concentration and HyA content. From scanning electron microscopy observations, the lyophilized matrices possess multi pore structures. The HyA-collagen composite matrices using this improved method will be useful in the preparation of cartilage regenerative scaffolds, and this methodology may be applied to other polyanion-polycation combinations as well.