Alginate beads have numerous biomedical applications, ranging from cell encapsulation to drug release. The present study focuses on the controlled release of glucose from calcium-alginate beads. The effects of alginate concentrations (1-6 wt %) and calcium chloride concentrations (0.1-1.0M) on glucose release from beads were examined. It was found that the time required for complete glucose release from beads could be tuned from 15 min to over 2 h, simply by varying alginate and calcium chloride concentrations in beads. For calcium-alginate beads with sodium alginate concentrations of 1-4 wt %, higher sodium alginate concentrations lead to more prolonged release of glucose and thus a smaller value of a rate constant k, a parameter shown to be proportional to the diffusion coefficient of glucose in the alginate gel. For beads with sodium alginate concentrations of 4-6 wt %, there was no statistically significant difference in k values, indicating a lower limit for glucose release from calcium-alginate beads. Similarly, higher calcium chloride concentrations appear to extend glucose release, however, no conclusive trend can be drawn from the data. In a 50 : 50 mixture of calcium-alginate beads of two different alginate concentrations (1 and 4 wt %), glucose release showed a two-step profile over the time range of 20-50 min, indicating that the pattern and time of glucose release from beads can be tuned by making combinations of beads with varying alginate and/or calcium chloride concentrations. (c) 2007 Wiley Periodicals, Inc.