Characterization and validation of a hybrid hydrogel for DLP bioprinting

3D bioprinting is a cutting-edge technology that has significantly advanced the fields of tissue engineering and regenerative medicine. By building tissues layer by layer, it enables the precise assembly of biological materials, including living cells, to create complex structures that closely mimic the architecture and function of human tissues. The development of bioinks, particularly those based on hydrogels, has been instrumental in this context. Hydrogels, with their high-water content and tunable properties, provide the necessary support and functionality, making them ideal for the fabrication of biologically relevant tissue models. This thesis focuses on the optimization of a hybrid hydrogel based on GelMA (gelatin methacrylate) and PEGDA (polyethylene glycol diacrylate) for use in 3D bioprinting, specifically for the creation of a liver model that accurately reproduces the complex structure of the organ. The liver plays a vital role in metabolism, detoxification and protein synthesis, and presents significant challenges for its in vitro reproduction. To address these challenges, Digital Light Processing (DLP), known for its high precision and control, was used as a bioprinting technique. The research activities of this thesis aimed at optimizing the mechanical properties of these hydrogels to ensure the stability and functionality of the bioprinted liver constructs. To this end, several tests were conducted on the material, including rheological measurements to assess viscoelastic properties, degradation and swelling tests to assess the stability over time, and fluorescence recovery after photobleaching (FRAP) to determine the diffusion characteristics within the hydrogels. Atomic force microscopy (AFM) was also used to measure Young’s modulus, providing insight into the stiffness of the hydrogel. Furthermore, a biological validation of the optimized hydrogels was performed, assessing the viability, proliferation and functionality of the cells within the bioprinted constructs. This validation confirmed that the hydrogels provided a suitable environment for cell growth while maintaining their structural integrity. In summary, this research contributes to the development of more reliable and functional hydrogels for 3D bioprinting, with specific applications in the creation of complex tissue models such as the liver.