Synthesis and properties of melt-processable hyaluronan esters.

A series of melt-processable hyaluronan (HA) esters were synthesized for potential biomedical applications (e.g., hot molding with thermoplastic ultra high molecular weight polyethylene for total joint replacements or molding tissue engineering scaffold). A silylated complex of HA with cetyltrimethylammonium cations (silyl HA-CTA) was used as the starting material. The reactions were performed with acid chlorides as the acylation agents in xylenes or no solvent other than the acid chloride. The disappearance of all characteristic FT-IR vibration bands associated with the -OSi(CH3)3 groups and the appearance of the strong ester carbonyl peak at 1753 cm-1 demonstrated the success of esterification. Thermoplasticity was achieved when the length of aliphatic chains in the HA esters was equal to or greater than 10 carbon atoms. It was found that the longer the ester chain, the lower the melting point; thus, to meet various needs different melting temperatures can be obtained by adjusting the acid chloride chain length.