Demineralized bone bioinks with enhanced odontogenic differentiation: Synthesis and characterization

We developed a photocrosslinkable hydrogel, DbpGMA, by chemically functionalizing demineralized bone powder (DBP) with glycidyl methacrylate (GMA). Bone particles smaller than 90 μm effectively preserved the collagenous matrix after demineralization, producing a uniform DBP sol with good processability. GMA modification was more efficient in HCl-based DBP sol than in acetic acid-based sol, resulting in a higher degree of methacrylation.The DbpGMA hydrogels exhibited tunable mechanical and rheological properties depending on polymer concentration and UV exposure. Notably, increasing the concentration from 10 % to 30 % markedly reduced the gelation time from 130 s to 10 s, while extending the UV curing duration from 0 s to 10 s resulted in a substantial reduction in internal pore size from >75 μm to <12 μm. Among the tested formulations, 20 % DbpGMA provided an optimal balance between mechanical strength (compressive modulus of 150.3 ± 12.2 kPa at 10 % strain) and DLP print fidelity. Additionally, incorporating 0.1 % (w/v) tartrazine as a photoabsorber significantly improved shape fidelity by controlling light penetration, which facilitated the printing of delicate vascular channels with a 0.7 mm resolution.DbpGMA demonstrated excellent cytocompatibility, supporting the proliferation and odontogenic differentiation of dental pulp stem cells (DPSCs) even in the absence of external inducers. The combination of natural bone-derived extracellular matrix composition, photocurability, and high print resolution highlights the versatility of DbpGMA as a DLP bioink. Overall, DbpGMA represents a biologically functional and DLP-compatible platform for fabricating high-resolution, cell-laden constructs, offering significant potential for dentin-pulp regeneration and dental hard tissue engineering.