Direct ink writing of collagen scaffolds functionalized with antimicrobial peptides: A proof-of-concept study for bone tissue engineering.

We developed a novel collagen-based biomaterial ink with an integrated antimicrobial peptide (AMP) intended for bone tissue engineering, enabling fabrication of a 3D-printed collagen-scaffold with antibacterial activity. A chemically synthesized derivative of the human AMP KR-12 was designed for enhanced stability and activity against Gram-positive bacteria that are key pathogens in fracture-related infections. KR-12 was covalently conjugated to collagen using both non-selective and maleimide-based coupling strategies. The choice of conjugation method significantly influenced peptide incorporation efficiency and functional availability. Among the resulting formulations, the ink in which KR-12 was conjugated with collagen using a short linker (Coll-cysKR12-Q5KD9A SL) demonstrated suitable rheological properties for extrusion-based 3D printing and reduced the growth of Staphylococcus aureus in surrounding culture media. Additionally, this scaffold demonstrated cytocompatibility with primary human osteoblasts (hOBs) in indirect assays. All collagen-KR-12 hydrogels were successfully printed, with Coll-cysKR12-Q5KD9A SL enabling the finest structural resolution. These findings provide an initial proof-of-concept for peptide-functionalized collagen scaffolds fabricated by direct ink writing. However, further studies are required to evaluate scaffold-associated antibacterial activity, biofilm inhibition, and direct osteogenic performance.