Organisms have derived specific sets of traits in response to common selection pressures that serve as guideposts for optimal biological designs. A prime example is the evolution of toughened structures in disparate lineages within plants, invertebrates, and vertebrates 1-4. Extremely tough structures can function much like armor, battering rams, or reinforcements that enhance the ability of organisms to win competitions, find mates, acquire food, escape predation, and withstand high winds or turbulent flow. Some of these natural systems have developed well-orchestrated strategies, exemplified in the biological tissues of numerous animal and plant species, to synthesize and construct materials from a limited selection of available starting materials. The resulting structures display multiscale architectures with incredible fidelity and often exhibit properties that are similar, and frequently superior to, mechanical properties exhibited by many engineering materials 1-4. In specific instances, comparative analyses of multiscale structures have pinpointed which design principles have arisen convergently; when more than one evolutionary path arrives at the same solution, we have a good indication that it is the best solution. This is required for survival under extreme conditions. We describe a few of these systems that show convergent design and describe how controlled syntheses and hierarchical assembly using organic scaffolds 5-8 lead to these integrated macroscale structures 8-12. We describe their function and translation to biomimetic and bioinspired materials used for engineering applications 13-16.

1. “Biological and Biologically-Inspired Functional Nanostructures: Insights into Structural, Optical, Thermal, and Sensing Applications”, C-H Sung et al., Advanced Materials, accepted (2025). DOI:10.1002/adma.202509281
2. “Convergent design evolution of multiscale biomineralized structures in extinct and extant organisms: struts, interfaces, and helicoids”, V. Perricone et al., Communications Materials, 5, (227) (2024) 1 – 18.
3. “Multiscale toughening mechanisms in biological materials and bioinspired designs”, W. Huang et al., Adv. Mat., 31, 1901561 (2019).
4. “Nano-Architected Tough Biological Composites from Assembled Chitinous Scaffolds”, W. Huang et al., Acc. Chem. Res., 50 (10) (2022) 1360-1371.
5. “Radular teeth matrix protein 1 directs iron oxide deposition in chiton teeth”, M. Nemoto et al., Science, 389 (6760) (2025) 637-643.
6. “Mesocrystalline Ordering and Phase Transformation of Iron Oxide Biominerals in the Ultrahard Teeth of Cryptochiton stelleri,” T. Wang et al., Small Structures, (2022) 2100202.
7. “Fibrous Anisotropy and Mineral Gradients within the Radula Stylus of Chiton: Controlled Stiffness and Damage Tolerance in a Flexible Biological Composite”, J.E. Lee et al., J. Comp. Mater., 57 (4) (2022).
8. “Phase transformations and structural developments in the radular teeth of Cryptochiton stelleri,” Q. Wang, Adv. Funct. Mater., 23 (2013) 2908–2917.
9. “Toughening Mechanisms of the Elytra of the Diabolical Ironclad Beetle”, J. Rivera et al., Nature, 586, 543-548 (2020).
10. “A natural impact resistant bi-continuous composite nanoparticle coating”, W. Huang et al., Nat. Mat. 9, 1236-1243 (2020).
11. “The Stomatopod Dactyl Club: A Formidable Damage-Tolerant Biological Hammer”, J. Weaver et al., Science, 336 1275-1280 (2012).
12. “Analysis of an ultra hard magnetic biomineral in chiton radular teeth,” J. Weaver et al., Materials Today, 13 (2010) 42-52.
13. “Bioinspired SiC/Chitosan impact resistant coatings”, T. Hao et al. Adv. Funct. Mater., 35 (2025), 2417291.
14. “Direct ink write printing of chitin-based gel fibers with customizable fibril alignment, porosity, and mechanical properties for biomedical applications”, D. Montroni, et al., J. Funct. Biomat., 13 (2) (2022) 83.
15. “Electrocatalytic N-Doped Graphitic Nanofiber – Metal/Metal Oxide Nanoparticle Composites”, H. Tang et al., Small, 14, 1703459 (2018).
16. “Bio-Inspired Impact Resistant Composites”, L.K. Grunenfelder et al., Acta Biomat., 10, 3997-4008 (2014).