Deformation and failure of protein materials in physiologically extreme conditions and disease

Buehler, Markus J.; Yung, Yu Ching

doi:10.1038/nmat2387

Cited by 307 publications

(314 citation statements)

References 138 publications

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“…molecular defects at the level of single amino acids, or a few Ångstrom in lengthscale) in the collagen type I gene leads to mechanical weakness at larger scales [82,83] due to a softening of the tropocollagen molecule's stiffness and a significant reduction of the intermolecular adhesion [84,85]. This example shows that under disease conditions, the intrinsic repair and toughening mechanisms of bone can fail to function properly and lead to a rapid breakdown of the tissue [86].…”

Section: Discussionmentioning

confidence: 99%

On the effect of X-ray irradiation on the deformation and fracture behavior of human cortical bone

Barth

Launey

MacDowell

et al. 2010

Bone

183

109

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In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistancecurve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the progressive elimination of the bone's capacity for plastic deformation which restricts the intrinsic toughening from the formation "plastic zones" around crack-like defects. Deep-ultraviolet Raman spectroscopy indicated that this behavior could be related to degradation in the collagen integrity.

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Section: Discussionmentioning

confidence: 99%

On the effect of X-ray irradiation on the deformation and fracture behavior of human cortical bone

Barth

Launey

MacDowell

et al. 2010

Bone

183

109

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“…Similar to their role in other mechanical proteins [15][16][17][18][19][20][21], it has been hypothesized that H-bond arrays in beta-sheet nanocrystals reinforce the polymeric network under mechanical stretch, by forming interlocking regions that transfer the load between chains [13,22]. In particular, Termonia's pioneering empirical two-phase model based on experimental data has been instrumental in explaining the importance of the ratio and size of crystalline and semi-amorphous domains, at a time when large-scale atomistic simulations of spider silk constituents were impossible due to the lack of suitable force fields and computational resources [22].…”

Section: Introductionmentioning

confidence: 92%

Molecular and Nanostructural Mechanisms of Deformation, Strength and Toughness of Spider Silk Fibrils

Keten²,

et al. 2010

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“…We also note that the maximum forces we could reversibly apply to the spores were consistently higher for the cotE gerE mutant than the wild type, which also contributed to the relative increase in energy density of these mutants. This favorable outcome suggests that an improved understanding of the hierarchical spore ultrastructure under extreme forces 21 can lead to further increases in energy density and strain response through genetic engineering of spores.…”

Section: Spores Of Bacillus As Building Blocks Of High Energy Densitymentioning

confidence: 99%

Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators

et al. 2014

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Materials that respond mechanically to external chemical stimuli have wide--ranging applications in biomedical devices, adaptive architectural systems, robotics, and energy harvesting 1 . Synthesis and design principles inspired by biological systems have led to materials with capabilities for highly controlled and complex shape change 2 , oscillations 3 , fluid transport 4 , and homeostasis 5 . Despite the enhanced control over material behavior, the effectiveness of synthetic stimuli--responsive materials in generating work has been limited when compared to mechanical actuators 6 . Biological organisms with structures responsive to water gradients could potentially offer a solution for the limited work density of stimuli--responsive materials. Because water--responsive biological structures accomplish vital tasks like ascent of sap 7,8 , dispersal and self--burial of seeds 9,10 , they could possibly exhibit high energy densities and serve as building blocks of stimuli--responsive materials effective in generating work. Furthermore, biological nature of these materials offers the possibility of improving their characteristics through genetic mutations 11,12 . Here we report the discovery that the response of the spores of Bacillus to water potential gradients exhibit energy densities more than 10 MJ/m 3 , exceeding best synthetic water--responsive materials by 1000--fold 13,14 . We also identified a mutant spore form that nearly doubles the energy density relative to its wild type, highlighting the possibility for further improvements with genetic engineering of spores. We found that spores can self--assemble into dense, submicron--thick monolayers on substrates like silicon microcantilevers and elastomer sheets, creating bio--hybrid hygromorph actuators 15 . The spore monolayers forming these hygromorphs exhibited high--energy density and rapid response to changing water potentials. As an application of the strong mechanical response of spores, we have built an energy harvesting device that can remotely generate electrical power from an evaporating body of water. These results demonstrate that spores have a significant potential as building blocks of stimuli--responsive materials with dramatically enhanced capabilities for energy harvesting, storage, and actuation of robotic devices.Bacillus spores are dormant cells that can withstand harsh environmental conditions for long periods of time and still maintain biological functionality 16 (Fig. 1a,b). Despite their dormancy, spores are dynamic structures. For example, Bacillus spores respond to changes in relative humidity (RH) by expanding and shrinking and changing their diameter by as much as 12% 17--19 . We have used an atomic force microscope (AFM) based experiment (Fig. 2c) to determine the energy density of individual spores as they respond to changes in RH. By adjusting force and RH, we have created a thermodynamic cycle, in which individual spores go through four stages illustrated in Fig. 1d. In stage I, the spores rest at low RH (~20%). In stage II,...

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Deformation and failure of protein materials in physiologically extreme conditions and disease

Cited by 307 publications

References 138 publications

On the effect of X-ray irradiation on the deformation and fracture behavior of human cortical bone

On the effect of X-ray irradiation on the deformation and fracture behavior of human cortical bone

Molecular and Nanostructural Mechanisms of Deformation, Strength and Toughness of Spider Silk Fibrils

Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators

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