期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2006
卷号：103
期号：47
页码：17741-17746
DOI：10.1073/pnas.0604237103
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：In biomineralized tissues such as bone, the recurring structural motif at the supramolecular level is an anisotropic stiff inorganic component reinforcing the soft organic matrix. The high toughness and defect tolerance of natural biomineralized composites is believed to arise from these nanometer scale structural motifs. Specifically, load transfer in bone has been proposed to occur by a transfer of tensile strains between the stiff inorganic (mineral apatite) particles via shearing in the intervening soft organic (collagen) layers. This raises the question as to how and to what extent do the mineral particles and fibrils deform concurrently in response to tissue deformation. Here we show that both mineral nanoparticles and the enclosing mineralized fibril deform initially elastically, but to different degrees. Using in situ tensile testing with combined high brilliance synchrotron X-ray diffraction and scattering on the same sample, we show that tissue, fibrils, and mineral particles take up successively lower levels of strain, in a ratio of 12:5:2. The maximum strain seen in mineral nanoparticles ({approx}0.15-0.20%) can reach up to twice the fracture strain calculated for bulk apatite. The results are consistent with a staggered model of load transfer in bone matrix, exemplifying the hierarchical nature of bone deformation. We believe this process results in a mechanism of fibril-matrix decoupling for protecting the brittle mineral phase in bone, while effectively redistributing the strain energy within the bone tissue.
关键词：biomineralization ; deformation mechanisms ; in situ tensile testing ; micromechanics of bone ; synchrotron radiation
