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Preparation of core–shell microcapsules using nanodispersed fibroin



An elaborate control of fibroin self-assembly is critical in determining the size, structure, and release properties of a microcapsule. This report describes the preparation of microspheres in the submicron range using an aqueous fibroin solution nanoemulsified in decane with a mixed detergent solution of Tween 80 and Span 80. Nanodispersed water droplets containing fibroin molecules were dried under vacuum to facilitate the coalescence of fibroin and then transformed to suspended particles in the range of 200–1200 nm in diameter. The method was also applied to encapsulate dextran and fluorescein isothiocyanate-dextran (FITC-dextran), producing core–shell structured microcapsules as identified by scanning electron microscopy and confocal scanning laser microscopy. The microcapsule yield was in the range of 82–85% per fibroin consumed. The encapsulation efficiency was 64% for the microcapsules fabricated from a nanoemulsion containing 0.1 mg of FITC-dextran per mg fibroin. Approximately 70.5% of the core material was released within 2 weeks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011