Structural and mechanical characterization of crosslinked and sterilised nanocellulose-based hydrogels for cartilage tissue engineering

Nanocellulose is a natural biopolymer derived from cellulose. Combined with sodium alginate, it is used to 3D print hydrogels for articular and nasal cartilage engineering and shows good integration, promising cartilage regeneration and mechanical stability over 60 days of implantation in mice. Yet, little is known about their structural and mechanical properties, particularly the impact of crosslinking and sterilisation methods. This study investigates the impact of different calcium chloride crosslinker concentrations and sterilization methods on the structural and mechanical properties of nanocellulose-based hydrogels containing plant-derived cellulose nanofibrils, cellulose nanocrystals or a blend of the two. Crosslinking significantly alters the overall network distribution, surface morphology, pore size and porosity of the hydrogels. Sterilisation has a striking effect on pore size and affects swelling depending on the sterilisation method. The effect of crosslinker and sterilisation on the overall properties of the hydrogels was reliant on the form of nanocellulose that comprised them.