Direct ink writing of biocompatible chitosan/non-isocyanate polyurethane/cellulose nanofiber hydrogels for wound-healing applications

The demand for new biocompatible and 3D printable materials for biomedical applications is on the rise. Ideally, such materials should exhibit either biodegradability or recyclability, possess antibacterial properties, and demonstrate remarkable biocompatibility with no cytotoxic effects. In this research, we synthesized biocompatible and 3D printable hydrogels tailored for biomedical applications, such as wound healing films, by combining antibacterial double-quaternized chitosan (DQC) with cystamine-based non-isocyanate polyurethane (NIPU-Cys) - a material renowned for enhancing both the flexibility and mechanical properties of the hydrogels. To improve the rheological behavior, swelling attributes, and printability, cellulose nanofibrils were introduced into the matrix. We investigated the impact of DQC on degradability, swelling capacity, rheological behavior, printability, and cell biocompatibility. The slightly cytotoxic nature associated with quaternary chitosan was evaluated, and the optimal concentration of DQC in the hydrogel was determined to ensure biocompatibility. The resulting hydrogels were found to be suitable materials for 3D printing via a direct ink writing technique (DIW), producing porous, biocompatible hydrogels endowed with valuable attributes suitable for various wound-healing applications.