Loading of Bacterial Cellulose Aerogels with Bioactive Compounds by Antisolvent Precipitation with Supercritical Carbon Dioxide

Macromolecular Symposia 08/2010; 294(2):64-74. DOI: 10.1002/masy.201000008


Bacterial cellulose aerogels overcome the drawback of shrinking during preparation by drying with supercritical CO(2). 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 CO(2) 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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    • "Beyond that, good biocompatibility and low immunogenic potential (Helenius et al., 2006; Klemm, Schumann, Udhardt, & Marsch, 2001) render BC a promising material for various biomedical applications. This comprises their use as artificial blood vessels (Klemm et al., 2001), semi-permanent artificial skin (Petersen & Gatenholm, 2011), as well as matrices for slow-release applications (Haimer et al., 2010), nerve surgery (Klemm et al., 2001), engineering of bone tissue (Zaborowska et al., 2010) or artificial knee menisci (Bodin, Concaro, Brittberg, & Gatenholm, 2007). Quantitative replacement of water by an organic solvent and subsequent extraction of the organic solvent from the porous BC matrix with supercritical carbon dioxide ( scCO 2 ) has been demon- strated to be the most successful approach for converting BC hydrogels into the respective aerogels . "
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    • "Intriguing features such as densities B8 mg cm -3 (Liebner et al. 2010 ), low heat transmission, high interconnected porosity (B99.99 %) and void surface area (B650 m -2 g -1 ) render cellulose aerogels promising materials for a large variety of technical applications. Potential fields of use are high-performance thermal insulation (Plawsky et al. 2010 ), lightweight construction materials (Granstrom et al. 2011), oil–water separation (Cervin et al. 2012), photo-switchable (Kettunen et al. 2011 ) or shape-recovering superadsorbers (Zhang et al. 2012), bio-inspired cargo carriers on water and oil (Jin et al. 2011), adsorption of pollutants from air and water, catalysis (Koga et al. 2012), energy storage (Razaq et al. 2012; Hu et al. 2013), temporary templates (Korhonen et al. 2011), hemodialysis (Carlsson et al. 2012), controlled drug release in wound treatment (Haimer et al. 2010), or regenerative therapies where cellulosic aerogels have been studied as artificial blood vessels (Klemm et al. 2001), cartilage tissue (Bodin et al. 2007), or cell scaffolding materials (Liebner et al. 2011). Covalent immobilisation of quantum dots on the large inner surface area of cellulosic aerogels is a new approach that is considered to further expand the application potential of cellulosic aerogels. "
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