Equilibrium water content of microspheres based on cross-linked dextran

In this paper a method is presented to determine the equilibrium water content of microspheres with a hydrogel character based on cross-linked dextran. The water content was established by determination of the increase in blue dextran concentration after incubation of this solution with dried microspheres. An excellent correlation between the actual and predicted water contents was observed for microspheres with a moderate to high cross-link density. On the other hand, for particles with low cross-link density, the equilibrium water content was higher than predicted. This could be fully ascribed to swelling of the microspheres.