Novel multi-component synergistic bioink that balances biocompatibility and mechanical strength for cartilage regeneration

Hydrogels, owing to their porous network structure resembling the extracellular matrix (ECM), have become essential scaffold materials in the field of cartilage tissue engineering. Among them, gelatin methacrylate (GelMA) hydrogels are widely used in bioink development due to their excellent biocompatibility, biodegradability, and tunable photo-crosslinking properties. However, the high biocompatibility of pure GelMA often comes at the cost of mechanical strength, limiting its applicability in cartilage regeneration. To overcome this trade-off, this study developed composite bioinks based on GelMA, silk fibroin (SF), and polyethylene oxide (PEO) for fabricating porous hydrogel scaffolds, which were then systematically characterized in terms of morphology, porosity, hydrophilicity, mechanical strength, rheological behavior, printability, and cytocompatibility. In this design, PEO serves as a porogen to generate highly porous structures (porosity up to 88%), while SF compensates for the mechanical loss caused by PEO, enabling the scaffold to retain a compression strength of up to 29.10 kPa. Among the tested formulations, the 10% GelMA/1% SF/1.5% PEO (1%=0.01 g/mL) bioink exhibited excellent printability, mechanical integrity, and cytocompatibility, and it supported a robust deposition of collagen II and aggrecan by chondrocytes after printing. This work provides a versatile strategy for balancing the biocompatibility and mechanical robustness in bioinks, offering a promising platform for next-generation cartilage tissue engineering scaffolds.