Robustness-Strength Performance of Hierarchical Alpha-Helical Protein Filaments

The origin of how naturally occurring biological protein materials (e.g. cellular protein filaments, spider silk, bone, tendon, skin) are capable of unifying disparate mechanical properties such as strength (ability to sustain large stresses without fracture) and robustness (ability to undergo deformation without fracture, despite the presence of defects, equivalent to toughness) is of significant interest (Figure 1). However, the molecular basis of these properties remains largely unknown [1–3].