Calcium ion cross-linking alginate/dexamethasone sodium phosphate hybrid hydrogel for extended drug release.

•Calcium ion instructed the co-assembly of Dexp and Alginate to generate a hybrid hydrogel.•Ca2+/Dexp/alginate hybrid hydrogel could greatly extend drug release in vivo.•Ca2+/Dexp/alginate hybrid hydrogel could significantly improve the drug bioavailability.