Cellulose nanocrystals reinforced highly stretchable thermal-sensitive hydrogel with ultra-high drug loading

Hydrogels often have poor mechanical properties which limit their application in load-bearing tissues such as muscle and cartilage. In this work, a near-infrared light-triggered stretchable thermal-sensitive hydrogel with ultra-high drug loading was developed by a combination of natural polymeric nanocrystals, a network of synthetic thermo-responsive polymer, and magnetic Fe₃O₄ nanoparticles. The hydrogels comprise cellulose nanocrystals (CNCs) decorated with Fe₃O₄ nanoparticles (Fe₃O₄/CNCs) dispersed homogeneously in poly(N-isopropylacrylamide) (PNIPAm) networks. The composite hydrogels exhibit an extensibility of 2200%. Drug loading of vancomycin (VCM) reached a high value of 10.18 g g^-1 due to the dispersion of Fe₃O₄/CNCs and the interactions between the CNCs and the PNIPAm network. Importantly, the hydrogels demonstrated a thermo-response triggered by NIR, with the temperature increasing from 26 to 41 °C within 60 s. The hydrogels have high biocompatibility evidenced by cell proliferation tests, illustrating that these hydrogels are promising as dressings for wound closure, and wound healing.