Injectable Polysaccharide Hydrogels Reinforced with
Cellulose Nanocrystals: Morphology, Rheology, Degradation, and Cytotoxicity
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Abstract
Injectable
hydrogels based on carboxymethyl cellulose and dextran,
reinforced with rigid rod-like cellulose nanocrystals (CNCs) and aldehyde-functionalized
CNCs (CHO–CNCs), were prepared and characterized. The mechanical
properties, internal morphology, and swelling of injectable hydrogels
with unmodified and modified CNCs at various loadings were examined.
In all cases, gelation occurred within seconds as the hydrogel components
were extruded from a double-barrel syringe, and the CNCs were evenly
distributed throughout the composite, as observed by scanning and
transmission electron microscopy. When immersed in purified water
or 10 mM PBS, all CNC-reinforced hydrogels maintained their original
shape for more than 60 days. The maximum storage modulus was observed
in hydrogels with 0.250 wt % of unmodified CNCs and 0.375 wt % of
CHO–CNCs. CHO–CNCs acted as both a filler and a chemical
cross-linker, making the CHO–CNC-reinforced hydrogels more
elastic, more dimensionally stable, and capable of facilitating higher
nanoparticle loadings compared to hydrogels with unmodified CNCs,
without sacrificing mechanical strength. No significant cytotoxicity
to NIH 3T3 fibroblast cells was observed for the hydrogels or their
individual components. These properties make CNC-reinforced injectable
hydrogels of potential interest for various biomedical applications
such as drug delivery vehicles or tissue engineering matrices