Development and characterization of graphene derivative-GelMA hybrid bioinks for the generation of bioartificial tissue substitutes via 3D bioprinting

The fabrication of bioartificial tissue substitutes is a complex process that relies on the application of innovative biomaterials and manufacturing techniques enabling the generation of cell-laden scaffolds mimicking natural tissue interfaces. Among the many biomaterials, gelatin methacryloyl (GelMA) hydrogels have shown great potential for 3D bioprinting-based tissue engineering due to their high biocompatibility, biodegradability and tuneable mechanical properties. In this study, the potential use of hybrid hydrogels based on GelMA and a highly purified graphene-derivative (BioGraph) as biomaterials bioinks for extrusion-based 3D bioprinting was investigated. Formulations containing BioGraph concentrations of up to 0.1% (w/v) were well-suited for this technique, showing good extrudability with reduced clogging at the printing temperatures, effective photocrosslinking at the irradiances tested, high shape-fidelity and high resolution of the printed scaffold. In situ photocrosslinking tests revealed that BioGraph concentration decreased the speed of the photocrosslinking and the stiffness of the cured matrix. In vitro studies indicated that BioGraph content ≤ 0.1% (w/v) did not have an adverse impact on the viability and proliferation of rat adipose-derived mesenchymal stem cells (r-AMSCs). Similarly, acellular scaffolds implanted subcutaneously in rats showed a local macrophage-mediated inflammatory reaction and a collagen encapsulation process without any affection of surrounded host tissues. The addition of lower concentrations of BioGraph (0.025%, w/v) to the matrix resulted in enhanced macrophagic interactions and scaffold degradation in vivo, and r-AMSCs growth and proliferation in vitro. In conclusion, the GelMA-BioGraph hybrid hydrogels developed here demonstrate enhanced rheological and biological properties, tailored for extrusion-based 3D bioprinting with applications in the engineering of soft (neural, liver, etc.) or hard (bone) tissues.