Multiscale Biophysical Characterization of Ultra-Short Peptide Hydrogels

Ultra-short peptide (USP) hydrogels have emerged as a simple yet innovative class of biomaterial. Small peptide sequences (≤8 amino acid residues) self-assemble to form hierarchical nanofibrillar networks, which are characterized by minimalist design, biocompatibility, and the ability to mimic native extracellular matrix (ECM). These characteristics make USP hydrogels an excellent candidate for various biomedical applications, including 3D bioprinting, disease modeling, and targeted drug delivery. However, a thorough understanding of their hierarchical assembly and function is necessary to fully ascertain their potential. The current review provides an insight into the integrated biophysical toolkit needed to characterize USP hydrogels. We have critically summarized techniques used for examining the mechanical integrity (rheology), morphological properties (scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, X-ray diffraction, confocal), molecular interactions (circular dichroism, Fourier-transform infrared, nuclear magnetic resonance), and thermal characteristics (differential scanning calorimetry, thermogravimetric analysis) of USP hydrogels. By consolidating information from various biophysical techniques, one can rationally tailor hydrogels that exhibit desired mechanical and biological characteristics required for various biotechnological applications. Moreover, we also highlight the use of machine learning (ML) and artificial intelligence (AI) for predictive peptide engineering. Finally, our review underlines the current translational challenges and future prospects that position USP hydrogels as a robust platform for addressing the pressing needs in the biomedical field.