Creating and exploring carboxymethyl cellulose aerogels as drug delivery devices.

Carboxymethyl cellulose (CMC) is a well-known cellulose derivative used in biomedical applications due to its biocompatibility and biodegradability. In this work, novel porous CMC materials, aerogels, were prepared and tested as a drug delivery device. CMC aerogels were made from CMC solutions, followed by non-solvent induced phase separation and drying with supercritical CO. The influence of CMC characteristics and of processing conditions on aerogels' density, specific surface area, morphology and drug release properties were investigated. Freeze-drying of CMC solutions was also used as an alternative process to compare the properties of the as-obtained "cryogels" with those of aerogels. Aerogels were nanostructured materials with bulk density below 0.25 g/cm and high specific surface area up to 143 m/g. Freeze drying yields highly macroporous materials with low specific surface areas (around 5-18 m/g) and very low density, 0.01 - 0.07g/cm. Swelling and dissolution of aerogels and cryogels in water and in a simulated wound exudate (SWE) were evaluated. The drug was loaded in aerogels and cryogels, and release kinetics in SWE was investigated. Drug diffusion coefficients were correlated with material solubility, morphology, density, degree of substitution and drying methods, demonstrating tuneability of new materials' properties in view of their use as delivery matrices.