The homogenous alternative to biomineralization: Zn- and Mn-rich materials enable sharp organismal “tools” that reduce force requirements

We measured hardness, modulus of elasticity, and, for the first time, loss tangent, energy of fracture, abrasion resistance, and impact resistance of zinc- and manganese-enriched materials from fangs, stings and other “tools” of an ant, spider, scorpion and nereid worm. The mechanical properties of...

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Bibliographic Details
Published in:	Scientific reports Vol. 11; no. 1; p. 17481
Main Authors:	Schofield, R. M. S., Bailey, J., Coon, J. J., Devaraj, A., Garrett, R. W., Goggans, M. S., Hebner, M. G., Lee, B. S., Lee, D., Lovern, N., Ober-Singleton, S., Saephan, N., Seagal, V. R., Silver, D. M., Som, H. E., Twitchell, J., Wang, X., Zima, J. S., Nesson, M. H.
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 01-09-2021 Nature Publishing Group Nature Portfolio
Subjects:	631/158 631/443 631/57 639/301/54 Abrasion BASIC BIOLOGICAL SCIENCES Biomaterials Biomedical materials Biophysics Calcification Ecology Energy Energy conservation Fractures Hardness Humanities and Social Sciences Interfaces Jaw Manganese Mechanical properties Microscopy Mineralization multidisciplinary Physiology Salmon Science Science (multidisciplinary) Stings Teeth Zinc
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Summary:	We measured hardness, modulus of elasticity, and, for the first time, loss tangent, energy of fracture, abrasion resistance, and impact resistance of zinc- and manganese-enriched materials from fangs, stings and other “tools” of an ant, spider, scorpion and nereid worm. The mechanical properties of the Zn- and Mn-materials tended to cluster together between plain and biomineralized “tool” materials, with the hardness reaching, and most abrasion resistance values exceeding, those of calcified salmon teeth and crab claws. Atom probe tomography indicated that Zn was distributed homogeneously on a nanometer scale and likely bound as individual atoms to more than ¼ of the protein residues in ant mandibular teeth. This homogeneity appears to enable sharper, more precisely sculpted “tools” than materials with biomineral inclusions do, and also eliminates interfaces with the inclusions that could be susceptible to fracture. Based on contact mechanics and simplified models, we hypothesize that, relative to plain materials, the higher elastic modulus, hardness and abrasion resistance minimize temporary or permanent tool blunting, resulting in a roughly 2/3 reduction in the force, energy, and muscle mass required to initiate puncture of stiff materials, and even greater force reductions when the cumulative effects of abrasion are considered. We suggest that the sharpness-related force reductions lead to significant energy savings, and can also enable organisms, especially smaller ones, to puncture, cut, and grasp objects that would not be accessible with plain or biomineralized “tools”.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 USDOE AC05-76RL01830 PNNL-SA-163566
ISSN:	2045-2322 2045-2322
DOI:	10.1038/s41598-021-91795-y