The present invention relates to biocompatible crosslinked hyaluronic acidgel compositions, methods of their manufacture and use, and the crosslinkersused to make them. In one aspect of the invention, a polyethylene glycol crosslinkingagent is described for crosslinking hyaluronic acid preferably a multifunctionalone like 4-Arm Star PEG. In another aspect of the invention, crosslinking agentscomprising more than two functional groups are described. These multifunctionalcrosslinking agents can be used on their own to crosslink hyaluronic acid, orthey may be combined with bifunctional crosslinking agents in varying ratiosto make hyaluronic acid of tunable mechanical strength and hardness. The presentinvention also discloses hyaluronic acid compositions that have been coatedwith polyethylene glycol and methods of their use.
