Tuning hardness in calcite by incorporation of amino acids

TY - JOUR

T1 - Tuning hardness in calcite by incorporation of amino acids

AU - Kim, Yi-Yeoun

AU - Carloni, Joseph

AU - Demarchi, Beatrice

AU - Sparks, David

AU - Reid, David

AU - Kunitake, Miki

AU - Tang, Chiu

AU - Duer, Melinda

AU - Freeman, Colin

AU - Pokroy, Boaz

AU - Penkman, Kirsty Elizabeth Helena

AU - Harding, John

AU - Estroff, Lara

AU - Baker, Shefford

AU - Meldrum, Fiona C.

N1 - © 2016, The publisher. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details

PY - 2016/8/1

Y1 - 2016/8/1

N2 - Structural biominerals are inorganic/organic composites that exhibit remarkable mechanical properties. However, the structure–property relationships of even the simplest building unit—mineral single crystals containing embedded macromolecules—remain poorly understood. Here, by means of a model biomineral made from calcite single crystals containing glycine (0–7 mol%) or aspartic acid (0–4 mol%), we elucidate the origin of the superior hardness of biogenic calcite. We analysed lattice distortions in these model crystals by using X-ray diffraction and molecular dynamics simulations, and by means of solid-state nuclear magnetic resonance show that the amino acids are incorporated as individual molecules.We also demonstrate that nanoindentation hardness increased with amino acid content, reaching values equivalent to their biogenic counterparts. A dislocation pinning model reveals that the enhanced hardness is determined by the force required to cut covalent bonds in the molecules.

AB - Structural biominerals are inorganic/organic composites that exhibit remarkable mechanical properties. However, the structure–property relationships of even the simplest building unit—mineral single crystals containing embedded macromolecules—remain poorly understood. Here, by means of a model biomineral made from calcite single crystals containing glycine (0–7 mol%) or aspartic acid (0–4 mol%), we elucidate the origin of the superior hardness of biogenic calcite. We analysed lattice distortions in these model crystals by using X-ray diffraction and molecular dynamics simulations, and by means of solid-state nuclear magnetic resonance show that the amino acids are incorporated as individual molecules.We also demonstrate that nanoindentation hardness increased with amino acid content, reaching values equivalent to their biogenic counterparts. A dislocation pinning model reveals that the enhanced hardness is determined by the force required to cut covalent bonds in the molecules.

UR - http://www.scopus.com/inward/record.url?scp=84965050740&partnerID=8YFLogxK

U2 - 10.1038/nmat4631

DO - 10.1038/nmat4631

M3 - Article

SN - 1476-1122

VL - 15

SP - 903

EP - 910

JO - Nature Materials

JF - Nature Materials

IS - 8

ER -