The nanocomposite nature of bone drives its strength and damage resistance

Abstract

Crystallization of ACP with timeTo probe the stability of the observed ACP in disordered phase with respect to the adjacent HA nanocrystals, we performed TEM analysis of the same region after a 30-day time lapse. During the 30 days, the TEM sample was stored at room temperature in a N2 environment. Figure S1a shows the initial arrangement of ACP (left) and HA nanocrystals (right), as well as the diffraction pattern inset showing the crystallinity of the HA. Figure S1b shows the same region after the 30 day incubation period; the HA nanocrystals on the right appear to have grown, confirmed by the increased (112), (211), (300) intensities in the diffraction pattern inset; we also observe the emergence of (002) reflections after one month, which further proves the formation of crystals. These results demonstrate suggest that biogenic ACP is a precursor for crystalline cHA formation in bone in the observed conditions, as similarly observed by Mahamid et al 1 . Figure S1. Time lapse micrographs of amorphous and nanocrystalline regions. Deprotonated mineral structure in disordered phase taken before (a) and after (b) a 30 day incubation at room temperature in a nitrogen environment. The electron diffraction pattern after the incubation (b, inset) shows an increase in crystallinity as evidenced by more intense HA reflections and the emergence of the (002) spots when compared to the initial diffraction pattern (a, inset). Size Dependent Model ConstructionWe propose that the yield strength, , decreases as the probability of having a flaw (i.e. a pore) on the pillar surface increases; that is, surface flaws serve as probabilistic stress concentrators, which initiate failure during compression. This is manifested most prevalently in the larger pillars, with diameters > 500nm. At these nano and micro length scales, it is reasonable to consider bone as a fiber-

The Ultrastructure of Bone and Its Relevance to Mechanical Properties

“…Experimental validation of the mechanical properties of bone at the nanoscale is also very challenging. Relevant experimental studies include atomic force microscopy measurements combined with electron microscopy imaging (SEM and TEM) (e.g., [58][59][60]) and tests on micropillars of bone at a µm scale [61][62][63]. Theoretical models can give valuable insights on bone's response at the nanoscale and the structure-property relations of bone in general.…”

Advanced Structural Materials by Bioinspiration

“…All natural materials have common key features and design motifs, which are responsible of their significant improvement in properties compared to their building blocks. Most of them have a composite nature, whose structure is the results of a combination of stiff and soft components organized into a multi‐level hierarchical structure. At each level, it is possible to recognize a detailed organization, where each structural element has a specific size, hence contributing to increase the flaw tolerance of such materials.…”

Periosteum Extracellular‐Matrix‐Mediated Acellular Mineralization during Bone Formation

“…These nanoparticles have lengths of 60–90 nm and widths of 10–20 nm, which are similar to those of bone apatite crystals . The selected area electron diffraction (SAED) pattern reveals high crystallinity of CHA and electron diffraction concentrate rings attributed to the reflections of crystallographic planes of (002), (211), and (004) of CHA crystals . The lattice fringes (inset) confirm the highly ordered phase at the atomic level .…”

“…The electron diffraction signal of the crystallographic planes of (002), (211), and (004) of CHA crystals is weaker than that of synthetic CHA, indicating that the nanostructure of deproteinated porcine bone minerals is less ordered than that of synthetic CHA. The continuous rings in the SAED pattern of mineralized ECM scaffold indicate its polycrystalline nature, and crystal lattice image (inset) shows a reduced ordered nanostructure at the atomic level …”