Figure 1.

Arzt heptahedron indicating the seven key features of biological systems in nature that synthetic biomaterials still cannot reach, including self-assembly, multifunctionality, self-healing, the hierarchy of structure, evolution against environmental constraint, synthesis under T~300 K and P~1 atm, and hydration. Natural examples: (A) self-assembled peptide nanostructures with permission from Gazit (2007), (B) multifunctional butterfly wing with permission from Miyako et al. (2013), (C) gecko tail regeneration with permission from Gecko Tail Regeneration (2011), (D) evolution in Timema stick insects with permission from Nosil et al. (2018), and (E) hierarchical bone structure with permission from Wegst et al. (2015).