Ultra-Short Peptide Hydrogels as 3D Bioprinting Materials.

Ultra-short peptides (USPs; ≤7-8 amino acids) emerge as minimal self-assembling building blocks for hydrogel-based biomaterials. Their intrinsic biocompatibility, straightforward synthesis, and ease of tunability make them particularly attractive candidates for potential use in bioprinting. This review provides an overview of the properties of USPs along with their applications in three-dimensional (3D) bioprinting. We first discuss how peptide sequence, terminal and side-chain modifications, and environmental triggers govern USPs' self-assembly into nanofibers and 3D networks and how these supramolecular features translate into key rheological properties such as shear-thinning, rapid gelation, and mechanical tunability. We then survey reported applications in tissue engineering, wound healing, and organotypic models, as well as emerging ultra-short peptide-based systems for drug delivery, biosensing, and imaging, highlighting examples where printed constructs support cell viability, differentiation, and matrix deposition. Attention is given to hybrid and multi-material formulations in which USPs provide bioactivity while complementary components contribute structural robustness or additional functionality. Finally, this review outlines the main challenges that currently limit widespread adoption, including achieving high print fidelity with cytocompatible crosslinking, controlling batch-to-batch variability, and addressing the scalability, cost, and sustainability of peptide manufacturing. We conclude by discussing future opportunities such as AI-assisted peptide design, adaptive and multi-material bioprinting workflows, and greener synthetic routes, which together may accelerate the translation of ultra-short peptide-based bioinks from proof-of-concept studies to clinically and industrially relevant platforms.