Development of chitosan bioink: Effect of nanocellulose reinforcement in three-dimensional bioprinting applications

In this study, chitosan based bioinks reinforced with bacterial nanocellulose (BNC) and vegetal nanocellulose (VNC) were developed for extrusion based bioprinting applications. Chitosan was selected as the main polymeric component due to its biocompatibility and biodegradability, although its limited mechanical properties and printability require reinforcement strategies. To address these limitations, different concentrations of nanocellulose were incorporated into the formulations and their influence on bioink performance was evaluated. The resulting bioinks were characterized in terms of rheological behavior, printability, buildability, chemical composition (FTIR), thermal behavior (DSC), crystalline structure (XRD), mechanical properties, degradation, and biological properties. Nanocellulose incorporation improved the rheological, structural, and mechanical properties of the bioinks. A nanocellulose concentration of 1.0% w/w provided the best balance between flow behavior, shape fidelity and buildability. XRD and DSC analyses revealed differences associated with the nanocellulose source, with BNC exhibiting higher crystallinity and stronger interactions within the chitosan matrix than VNC. CH-BNC 1.0 showed superior compressive properties, while both nanocellulose sources contributed to the fabrication of stable structures with improved dimensional fidelity and vertical stability after printing. Biological evaluation demonstrated that both bioinks maintained high cell viability and showed no evidence of cytotoxicity under the conditions evaluated. Overall, the chitosan nanocellulose bioinks developed in this work represent a promising strategy for the fabrication of structurally stable and biologically compatible scaffolds for tissue engineering applications.