Abstract: The active ingredient was encapsulated in the alginate microgel using spray-drying technology. The microgel was crosslinked with calcium cations and chitosan to prepare the composite microspheres. Their application in controlled release was investigated using vitamin B₂ as the model drug. SEM analysis indicated that the aggregate structure was formed after compositely crosslinking of alginate microgel. In comparison with alginate microspheres crosslinked solely by calcium cations, the composite microspheres showed slower release of vitamin B₂, with t₅₀ prolonged by about 6 times. The longer the crosslinking time and higher dose of crosslinker, the slower the release of vitamin B₂. The release time of vitamin B₂ was extended to above 24 h at the loading amount of 16.0%-35.6%. The release process was dominated by Fickian diffusion.

Key words: alginate, chitosan, microgel, controlled release