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

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.

Cellulose nanofiber aerogel as a promising biomaterial for customized oral drug delivery

“…However, it does not always confirm that the CNF aerogel follows the Korsmeyer-Peppas model. Literature mentions that the release from the CNFs depends on the thickness of the film/aerogel 22 and also on the property of the drug and the type of cellulose used in the formulation. …”

Reinforcement of bacterial cellulose aerogels with biocompatible polymers

“…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). …”

Cellulosic materials as biopolymers and supercritical CO2as a green process: chemistry and applications

“…Liebner et al (2007Liebner et al ( , 2008 have reported the cellulose aerogels produced by scCO 2 drying of regenerated cellulose obtained by solvent exchange of a solution of cellulose in N-methylmorpholine-N-oxide; these materials showed surface areas of 172-284 m 2 /g. In another study, cellulose aerogels have been prepared by scCO 2 drying of the bacterial cellulose produced by the gram-negative bacterium Gluconacetobacter xylinum, resulting in highly porous dry cellulose aerogels showing a density of 8 mg/cm 3 (Figures 5 and 6;Haimer et al 2010, Liebner et al 2010. Cellulose gels have been dried in scCO 2 followed by calcination and subsequent doping by platinum nanoparticles, yielding nanostructured highly porous electrocatalysts used for oxygen reduction (Guilminot et al 2008).…”