Injectable hyaluronic acid hydrogel for 19F magnetic resonance imaging

Abstract We report on a 19 F labeled injectable hyaluronic acid (HA) hydrogel that can be monitored by both 1 H and 19 F MR imaging. The HA based hydrogel formed via carbazone reaction can be obtained within a minute by simple mixing of HA-carbazate and HA-aldehyde derivatized polymers. 19 F contrast agent was linked to with carbazate and thiol dually functionalized HA via orthogonal Michael addition reaction which afforded cross-linkable and 19 F labeled HA. The 19 F labeling of HA polymer did not affect the mechanical properties of the formed hydrogel. As a result, the shape of a hydrogel sample could be imaged very well by both 1 H MRI and high resolution 19 F MRI. This hydrogel has high potential in clinical applications since it is injectable, biocompatible, and can be tracked in a minimally invasive manner. The present approach can be applied in preparation of injectable 19 F labeled hydrogel biomaterials from other natural biomacromolecules.