Hyaluronic acid solutions—A processing method for efficient chemical modification

To ensure repeatability of these crosslinking procedures and thereby improve the degradation time of hyaluronic acid (HA)-based biomaterials in vitro, it is essential to have an understanding of the solution properties of HA. Control of HA dissolution is important because dissolution and solution degradation are concurrent processes during solution preparation. Complete dissolution is also important to maximize intermolecular crosslinking and reduce wasteful intramolecular reactions. Viscosity time profiles of HA solutions during dissolution have been obtained in order to optimize crosslinking efficiencies. Optimum dissolution occurs between 24 and 40 h when the HA is in a fully solvated disentangled state as indicated by the peak in the solvating curves which corresponds with Mark-Houwink a parameters of 0.76-0.85. The developed and characterized dissolution process was used to produce carbodii- mide crosslinked HA films that were found to be reproducible and stable when immersed in distilled water. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 145-152, 2013