Microcapsules for Enhanced Cargo Retention and Diversity

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 11; no. 24; pp. 2903 - 2909
• Main Authors: Zieringer, Maximilian A., Carroll, Nick J., Abbaspourrad, Alireza, Koehler, Stephan A., Weitz, David A.
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 01-06-2015; Wiley Subscription Services, Inc
• Subjects: Controlled release; Cosmetics; Drug delivery systems; Encapsulation; Leakage; microcapsules; Microfluidics; Nanotechnology; perfluoropolyethers; retention; Solvents; Stems; encapsulation; microcapsules; perfluoropolyethers; microfluidics; retention
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201403175

Prevention of undesired leakage of encapsulated materials prior to triggered release presents a technological challenge for the practical application of microcapsule technologies in agriculture, drug delivery, and cosmetics. A microfluidic approach is reported to fabricate perfluoropolyether (PFPE)‐based microcapsules with a high core‐shell ratio that show enhanced retention of encapsulated actives. For the PFPE capsules, less than 2% leakage of encapsulated model compounds, including Allura Red and CaCl2, over a four week trial period is observed. In addition, PFPE capsules allow cargo diversity by the fabrication of capsules with either a water‐in‐oil emulsion or an organic solvent as core. Capsules with a toluene‐based core begin a sustained release of hydrophobic model encapsulants immediately upon immersion in an organic continuous phase. The major contribution on the release kinetics stems from the toluene in the core. Furthermore, degradable silica particles are incorporated to confer porosity and functionality to the otherwise chemically inert PFPE‐based polymer shell. These results demonstrate the capability of PFPE capsules with large core–shell ratios to retain diverse sets of cargo for extended periods and make them valuable for controlled release applications that require a low residual footprint of the shell material.
Perfluoropolyether microcapsules with a high core–shell ratio are produced using double emulsion drops as templates. This microfluidic approach enables the encapsulation of aqueous and organic cargos with precise control over the capsule size and composition. The shell material provides a highly efficient diffusion barrier even for ionic encapsulants.