Bilayer gelatin-methacryloyl scaffold for pulp inflammation suppression and dentin-like tissue regeneration

Balancing pulp tissue inflammation and dentin regeneration is essential for maintaining tooth responsiveness and reparative ability in vital pulp therapy (VPT). Here, we describe a photocrosslinkable gelatin methacryloyl (GelMA) biomaterial electrospun into a bilayer fibrous scaffold with clinically relevant functions. It comprises a 10 % (w/v) GelMA layer loaded with ibuprofen (IBP, 10 % or 20 % w/w) for immunomodulation, and a 20 % GelMA layer containing amorphous magnesium phosphate (AMP, 5 % or 15 % w/w) to promote biomineralization. Fiber morphology, chemical composition, mechanical properties, swelling, enzymatic degradation, and release kinetics of IBP and Mg²⁺/PO₄^3- ions were evaluated. Bioactivity was assessed with human dental pulp stem cells (DPSCs), macrophages, an LPS-challenged artificial pulp chamber (APC) model, and subcutaneous implantation. All fibers were bead-free and porous, and photocrosslinking yielded pulp-like stiffness. IBP-loaded fibers showed an initial burst followed by sustained release over 14 days; AMP fibers released ions continuously for 7 days. IBP layer reduced IL-1α, TNF-α, and IL-6 secretion, inhibiting NF-κB activation without cytotoxicity. AMP layer increased ALP activity, mineral deposition, and expression of COL1A1, RUNX2, and ALPL. In the APC model, the bilayer scaffold downregulated IL1A, IL1B, and TNF within 3 h; after 14 days, it upregulated ALPL, DSPP, and OCN compared to controls under LPS. Subcutaneous implantation confirmed biocompatibility: IBP decreased M1 polarization, while AMP induced transient RUNX-2 followed by ALP and osteocalcin, indicating ongoing mineralization. The dual functionality of this bilayer scaffold suggests it may serve as a promising next-generation VPT biomaterial capable of controlling inflammation and guiding dentin-like tissue regeneration.