Thermoresponsive and biocompatible poly(N-isopropylacrylamide)-cellulose nanocrystals hydrogel for cell growth

We describe herein a poly(N-isopropylacrylamide) (PNIPAAm)-cellulose nanocrystals (CNC) hydrogel as thermoresponsive and biocompatible material. The hydrogel was generated with simple and robust mixing without need for complicated derivatization. The composition of the hydrogel was optimized for good stiffening and its biocompatibility was verified with fibroblast cells. The hydrogel was prepared using an osmotic dehydration method by tuning its water content and porosity without the incorporation of additional cross-linkers. The interaction of PNIPAAm and CNC was supported by the formation of a small endotherm at 30.5-33.5 °C observed with differential scanning calorimetry and a negative value for the enthalpy during the adsorption of both compounds by the isothermal titration calorimeter. The resulting PNIPAAm-CNC hydrogel (0.25 wt%; 0.5 wt%) showed better compatibility with fibroblasts than 0.5 wt% CNC alone. Our preliminary data indicates that it is possible to use the thermoresponsive characteristics of the material to influence cell behavior by temperature changes. PNIPAAm-CNC hydrogel offer a platform for the development of versatile and affordable plant-based materials for controllable 3D cell culture and the thermoresponsive nature of the material may help to develop novel applications for example in 3D-printing.