Synthesis, characterization, and evaluation of phosphated cross-linked konjac glucomannan hydrogels for colon-targeted drug delivery

Hydrogel systems of konjac glucomannan (KGM) cross-linked with trisodium trimetaphosphate (STMP) were prepared for colontargeting drug delivery. Swelling degrees of the hydrogels were measured in artificial gastrointestinal fluids and in sodium chloride solution with different concentrations to study their dependence on the cross-linking density and the ionic strength. The absorption of methylene blue was used to characterize the degree of the KGM cross-linking. In vitro release of model drug hydrocortisone was studied in presence and absence of ss-mannanase. KGM cross-linked with STMP was able to retard the release of the poorly water-soluble drug and could be biodegraded enzymaticallN. HN drocortisone release was cross-linking density dependent and controlled by degradation of the hydrogles.