3D printed anti-swelling hydrogel scaffold with dialdehyde cellulose nanocrystals

In this study, a novel hydrogel preparation method was developed to formulate a 3D printable hydrogel with low swelling ratio for biomedical scaffolds. Nanocellulose fibrils were first oxidized to synthesize dialdehyde cellulose nanocrystals (DACs). The aldehyde groups on DACs could crosslink with laponite nanoclay via an esterification reaction. The mechanism between the two materials through aldehyde and hydroxyl groups was further confirmed by FTIR results. To optimize the printability and printing quality of the prepared hydrogels, the rheological properties of the gels were carefully examined to understand the shear thinning effect and the thixotropic responses. An optimal hydrogel composition of 6 wt% laponite and 1 wt% DACs showed the best results to accurately print 3D structures with a nozzle dispenser. The printed gel structures exhibited high mechanical strength and low swelling effect without complicated post treatment steps. Several examples were also demonstrated to show the structural stability, accuracy, and cell viability of the printed hydrogel structures for potential in 3D bio-printing applications.