Background By integrating gelatin methacryloyl (GelMA) with osteoconductive β-tricalcium phosphate (β-TCP) via tissue engineering strategies, we developed an implantable scaffold designed for bone defect regions. This composite material holds promise for addressing the challenges associated with bone repair and functional reconstruction.

Objective To synthesize a GelMA/β-TCP/melanin nanoparticle (MNP) composite hydrogel and investigate its biocompatibility, reactive oxygen species (ROS)-scavenging capacity, biological properties, and osteogenic differentiation potential in MC3T3-E1 cells.

Methods Four types of hydrogels were prepared under 0.25% LAP (photoinitiator) and 405 nm light: GelMA, GelMA/β-TCP, GelMA/MNPs, and GelMA/β-TCP/MNPs, using 5% GelMA, 1% β-TCP, and 1 mg/mL MNPs. The microstructures of freeze-dried samples were characterized by scanning electron microscopy. Extracts from the four hydrogel groups were collected, with complete culture medium serving as a blank control. Biocompatibility was assessed using CCK-8 assay, live/dead staining, and TUNEL staining; anti-ROS activity was evaluated with DCFH-DA staining; biological property regulation was determined via phalloidin staining, Ki-67 immunofluorescence, and scratch wound assay; and osteogenic potential was assessed by RUNX2 and OCN immunofluorescence staining.

Results Freeze-dried GelMA/β-TCP/MNP hydrogel exhibited a rough, three-dimensional porous structure with an average pore size of (103.61 ± 16.90) μm, favorable for cell adhesion and proliferation. Biocompatibility assays indicated no obvious cytotoxicity in any group. Incorporation of MNPs into GelMA significantly enhanced intracellular ROS-scavenging activity. Biological property evaluations showed increased cell adhesion (phalloidin staining), promoted cell migration (scratch assay), and enhanced cell proliferation (Ki-67) in the GelMA/β-TCP/MNP group. Osteogenesis-related staining revealed that GelMA/β-TCP/MNP hydrogel exhibited the strongest osteoinductive ability compared with the control and other material groups.

Conclusion GelMA/β-TCP/MNP hydrogel demonstrates excellent biocompatibility and effective ROS-scavenging activity, and enhances cell adhesion, migration, and proliferation, promote osteogenic differentiation of MC3T3-E1 cells, indicating promising potential for bone tissue engineering applications.