The effect of hydration on the material and mechanical properties of cellulose nanocrystal-alginate composites

Alginate is commonly used in the form of hydrogels in biomedical applications. It is known to be highly sensitive to liquid exposure and can degrade or solubilize easily. This study attempts to improve the mechanical and material properties in various humidity conditions and in liquid immersion of thin alginate films with the addition of unmodified and oxidized cellulose nanocrystals (CNCs, CNC-Ts). CNCs and CNC-Ts were added to alginate composites in varying amounts, and the material and mechanical properties were measured in dry, humid, and liquid conditions. It was shown that the properties can be enhanced with the addition of nanocellulose as tested by liquid uptake, and mechanical testing. These results suggest that the addition of TEMPO-oxidized nanocellulose crystals improves the performance and longevity of alginate when exposed to phosphate buffer solution (PBS) compared to deionized water. This improved performance was shown to have a limited effect on the adhesion of mesenchymal stem cells (MSCs) to the surface of the nanocomposites.