Assistant Professor Lehigh University, Pennsylvania, United States
Introduction: Spider silk exhibits exceptional mechanical properties, including strength, toughness, and elasticity, surpassing those of man-made polymers and natural materials like Kevlar and steel. These properties are attributed to silk's unique hierarchical structure, featuring alternating nanoscale β-sheet-rich crystalline and amorphous domains. The crystalline regions provide strength, while the amorphous regions contribute flexibility. Combined with its biodegradability, silk presents promising opportunities for developing high-performance biomimetic materials.
Large-scale natural harvesting of silk is impractical due to the cannibalistic behavior of spiders, while recombinant production faces challenges such as low yield and genetic engineering difficulties. While synthetic methods allow for better control, they often face issues like low coupling efficiency and suboptimal mechanical properties.
Our study addresses these challenges by developing biocompatible silk mimics that replicate the molecular arrangements of natural silk through the conjugation of β-sheet forming peptides with hydrophilic polymers. This approach allows for precise tuning of peptide length and sequence to control self-assembly, as well as polymer modifications to manage amorphous and crystalline domains, offering a deeper understanding of silk and its properties.
Materials and
Methods: Peptides with varying lengths and sequences of amino acids were synthesized using standard solid-phase peptide synthesis. The peptides were coupled to a hydrophilic amorphous polymer, polyethylene glycol (PEG), via a click reaction. This approach enabled precise control over the resulting material’s properties, facilitating the design of silk mimics with tailored mechanical and structural characteristics.
Results, Conclusions, and Discussions: Rheology data showed that the hydrogel had a stiffness of approximately 170 kPa and retained around 82 kPa at ~10% strain, which is notably high for self-assembled peptide hydrogels. SAXS, CD, FTIR, and NMR analyses confirmed the successful formation of self-assemblies and provided insights into the characteristics of the crystalline domains.
The results demonstrate that modifying the β-sheet peptide significantly impacts mechanical properties, as anticipated. The incorporation of a valine-rich peptide enhanced the hydrogel’s performance, highlighting the importance of peptide sequence in optimizing material properties.
This study highlights the successful development of self-assembled peptide hydrogels with remarkable and highly adjustable mechanical properties. The observed properties are attributed to nanoscale structural modifications. These findings advance our understanding of designing silk-inspired biomaterials with customized mechanical attributes, enhancing their potential applications in tissue engineering, drug delivery, and biocompatible coatings.
