Fluorescent Nanofibrillar Hydrogels of Carbon Dots and Cellulose Nanocrystals and Their Biocompatibility

Synthetic nanofibrillar hydrogels resembling a natural extracellular matrix have emerged as a promising material in the biomedical field; however, achievement of multifunctional nanofibrillar hydrogels with good biocompatibility is still an important and challenging task. Herein, we report a fluorescent nanofibrillar hydrogel prepared with polyethyleneimine (PEI) and cellulose nanocrystals (CNCs) via one-step hydrothermal treatment. The nanofibrillar hydrogels are mainly formed from CNCs cross-linked by carbon dots (CDs) through hydrogen bonding and hydrophobic interactions. The nanostructures and the mechanical properties of the hydrogels are controlled by weight ratios of CNCs to PEI and the total concentration of CNCs and PEI. In comparison with other hydrogels from CNCs and CDs, the nanofibrillar hydrogels exhibit better mechanical properties with relatively high Young’s moduli. The hydrogels show relatively low cytotoxicity and good biocompatibility, which are demonstrated by in vitro cell culture and in vivo subcutaneous implantation in rats. This work provides a new approach to prepare biomimetic nanofibrillar hydrogels with fluorescence properties, thus offering a promising synthetic material resembling a natural extracellular matrix for bioapplications.