MICROCAPSULES PREPARED THROUGH INTERFACIAL CROSS-LINKING OF STARCH DERIVATIVES

An interfacial cross-linking process was applied to hydrosoluble starch derivatives: hydroxyethylstarch (HES) and carboxymethylstarch (CMS). It resulted in stable microcapsules, which could be easily lyophilized and gave free-flowing powders. Sodium salicylate was encapsulated in HES microcapsules. In vitro dissolution studies indicated that these walls allow a prolonged release of the tracer. CMS microcapsules exhibited hydrophilic properties, as shown by water-induced swelling and gel formation. All cross-linked polysaccharide microcapsules were characterized by a total resistance to digestive media. However, when a protein, human serum albumin (HSA) or gelatin, was added to the starch derivatives in the aqueous phase, the process provided biodegradable microcapsules. © 1990.