An original method for studying in vitro the enzymatic degradation of cross-linked starch microspheres.

A reproducible technique based on microvolume measurements has been described which can be used for the assessment of the enzymatic degradation of small samples of microspheres (typically 104 to 105 micrometer3). As a model, the degradation pattern of epichlorohydrin cross-linked starch microspheres by alpha-amylase has been studied in the range of 5 to 100 IU/l by this technique. On the one hand, analysis of the decrease in volume of the microspheres by a cubic root law suggested that the degradation profiles were dependent on the initial size distribution of the microspheres. On the other hand, no internal rupture of the microspheres was detected from size distribution data, suggesting that enzymatic degradation of starch microspheres is surface-controlled.