3D bioprinting of betamethasone-loaded gellan gum–polyethyleneimine composite hydrogels for ocular drug delivery

Transparent hydrogels have numerous applications in materials science and tissue engineering, particularly as materials for corneal repair. In this study, we developed a three-dimensional (3D)-bioprinted betamethasone sodium phosphate-loaded gellan gum (GG)–polyethyleneimine (PEI) composite hydrogel and assessed its performance in vitro. The bioinks used for 3D bioprinting were optimized based on their transparency and gelation properties. In the presence of an ionic crosslinker (citric acid), the GG–PEI blend transformed from a liquid precursor to an extrudable hydrogel with good printability and shape fidelity. The 2.5% GG–3% PEI hydrogel formulation had a transparency of 80%, a suitable degradation rate, and sufficient mechanical strength for application in corneal repair. The GG–PEI composite hydrogel displayed controlled and sustained release of betamethasone sodium phosphate. Moreover, the 3D-bioprinted composite hydrogel was biocompatible, as evidenced by the attachment, growth, and proliferation of corneal fibroblasts. Taken together, these findings suggest that the 3D-bioprinted GG–PEI composite hydrogel scaffold has the potential to control ocular inflammation and aid in corneal tissue healing.