Rheological behavior and microstructure of release-controlled hydrogels based on xanthan gum crosslinked with sodium trimetaphosphate

Xanthan-based hydrogels can be used for encapsulating and controlling release of nutrition ingredients, therapeutic agents, and cells in food and tissue engineering applications. Hydroxyl groups on the xanthan gum (XG) chains permitted the formation of the hydrogels through crosslinking XG with sodium trimetaphosphate (STMP). Dynamical oscillation tests were performed to monitor the in situ crosslinking process, and to evaluate the forming kinetics and mechanical stability for the XG-STMP hydrogels. The results indicated that the transition from hydrogen bonding to chemical crosslinking for the XG chains occurred and reached a balance approximately at 25 and 37 °C, respectively. The XG-STMP hydrogel networks with solid-like gel behavior exhibited more elastic and tougher to resist the deformation than the physical XG hydrogels. The XG-STMP hydrogels with porous and interconnected structure displayed good swelling and release-controlled properties. This work provides some valuable and fundamental information of the xanthan-based hydrogels for further application in biomaterials, medical and food engineering.