Integration of 3D Bioprinting in Bone Tissue Engineering Using Chitosan Hydrogels: Preliminary Experiments Based on Formulation and Characterization of Three Chitosan Hydrogels

In bone tissue engineering, chitosan hydrogel has become a promising material for scaffolds due to its biocompatibility and structural and functional similarities with glycosaminoglycans—essential components of the extracellular matrix. One of its key advantages is its ability to promote osteoblastic adhesion, which is crucial for initiating bone regeneration. Additionally, adding phosphate salts to chitosan mixtures serves two purposes: it stops the gel from forming too quickly during preparation—making it easier to handle and inject—and helps mesenchymal stem cells turn into bone-forming cells, which aids in creating bone tissue.

The advent of 3D bioprinting has revolutionized tissue engineering by enabling the fabrication of complex, patient-specific scaffolds with precise control over architecture and cell distribution. Chitosan hydrogels are considered attractive candidates for bioinks in 3D bioprinting due to their favorable biological properties. However, their application is hindered by inherent limitations, i.e., notably slow gelation rates and weak mechanical properties, which compromise the printability and structural integrity of the printed constructs.

In this study, we formulated and characterized three different chitosan-based thermosensitive hydrogels to evaluate their suitability as biomaterial inks for bone tissue engineering applications. The investigation focused on assessing their rheological behavior and mechanical performance—critical factors influencing printability and scaffold stability. Specifically, we determined the gelation time of each hydrogel and assessed their linear equilibrium modulus plateau through frequency sweep tests. Additionally, the compressive strength of the hydrogels was measured to evaluate their structural integrity under mechanical stress. Beyond these mechanical properties, we examined other essential characteristics, including swelling capacity and antibacterial activity, to provide a comprehensive understanding of their functional performance through a comparative analysis.

Our findings aim to inform the development of chitosan-based bioinks with enhanced properties, facilitating their application in 3D bioprinting for bone tissue engineering.