Loading of Bacterial Cellulose Aerogels with Bioactive Compounds by Antisolvent Precipitation with Supercritical Carbon Dioxide |
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Authors: | Emmerich Haimer Martin Wendland Kerstin Schlufter Katrin Frankenfeld Peter Miethe Antje Potthast Thomas Rosenau Falk Liebner |
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Institution: | 1. University of Natural Resources and Applied Life Sciences, Institute of Chemical and Energy Engineering, Muthgasse 107, A-1190 Vienna, Austria;2. FZMB - Research Center for Medical Technology and Biotechnology Ltd., Geranienweg 7, D-99947 Bad Langensalza, Germany;3. University of Natural Resources and Applied Life Sciences, Institute of Organic Chemistry, Muthgasse 18, A-1190 Vienna, Austria |
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Abstract: | Bacterial cellulose aerogels overcome the drawback of shrinking during preparation by drying with supercritical CO2. Thus, the pore network of these gels is fully accessible. These materials can be fully rewetted to 100% of its initial water content, without collapsing of the structure due to surface tension of the rewetting solvent. This rehydration property and the high pore volume of these material rendered bacterial cellulose aerogels very interesting as controlled release matrices. Supercritical CO2 drying, the method of choice for aerogel preparation, can simultaneously be used to precipitate solutes within the cellulose matrix and thus to load bacterial cellulose aerogels with active substances. This process, frequently termed supercritical antisolvent precipitation, is able to perform production of the actual aerogel and its loading in one single preparation step. In this work, the loading of a bacterial cellulose aerogel matrix with two model substances, namely dexpanthenol and L-ascorbic acid, and the release behavior from the matrix were studied. A mathematical release model was applied to model the interactions between the solutes and the cellulose matrix. The bacterial cellulose aerogels were easily equipped with the reagents by supercritical antisolvent precipitation. Loading isotherms as well as release kinetics indicated no specific interaction between matrix and loaded substances. Hence, loading and release can be controlled and predicted just by varying the thickness of the gel and the solute concentration in the loading bath. |
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Keywords: | aerogels bacterial cellulose controlled release supercritical antisolvent precipitation supercritical drying |
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