Computational investigation of the effect of water on the nanomechanical behavior of bone

Molecular origin of viscoelasticity in mineralized collagen fibrils

“… 34 Recently, a 2D finite element model has been proposed to investigate the effect of bound and structural water on bone mechanics, highlighting the ability of the material to tolerate external loads and microcracks, but without any specific speculation on intrinsic viscoelastic phenomena. 41 Moreover, the stiffness of the mineralized fibrils, which is monotonic with the %HA, has a linearly decreasing trend with the increase of the intrafibrillar water content, independent of the presence of minerals. 25 This interesting behavior gives the opportunity for a research question related to the effect of bound water on the viscoelastic properties of bone that, currently, have been studied mainly at the macroscale.…”

“…It plays a negligible role in stiffening the material [33][34][35] but has effects on the viscoelasticity at the macroscale 36 ; ii) structural water is present between the staggered mineralized fibrils to ensure the stabilization and assembly of bone ultrastructure 37,38 ; and iii) bound water fills the voids of the mineralized fibrils 39,40 , and is observable with nuclear magnetic resonance procedures 34 . Recently, a 2D Finite Element Model has been proposed to investigate the role of bound and structural water on bone mechanics, highlighting the ability of the material to tolerate external loads and microcracks but without any specific speculation on intrinsic viscoelastic phenomena 41 . Moreover, the stiffness of the mineralized fibrils, which is monotonic with the %HA, has a linearly decreasing trend with the increase of the intrafibrillar water content, independently of the presence of minerals 25 .This interesting behavior gives the opportunity for a research question related to the role of bound water on the viscoelastic properties of bone that, currently, have been studied mainly at the macroscale 20,36,42-44 . In this paper, we explore the viscoelastic properties of mineralized collagen fibrils based on the different mineral and water contents at the atomic scale.…”

Bone: An Outstanding Composite Material

“…Hence, removing bound water in the bone matrix makes bone stiffer, stronger, but more brittle at different length scales, because dry collagen loses its deformation and energy absorption capacity [42]. As stated by Leo et al [13], the lack of collagen external water promotes the formation not only of new inter-tropocollagen hydrogen bonds but also of intra-tropocollagen ones, which cause the microfibril gain of compactness and tubularity.…”

Bone hydration: How we can evaluate it, what can it tell us, and is it an effective therapeutic target?

“…The mechanical role of bound water removal under tension and compressive loads at the ultrastructural level has recently been modeled using 2D cohesive finite element analysis. Removal of water under tension reduced nano crack formation, compromised debonding between mineralized collagen fibrils and the extrafibrillar matrix subunits, and hindered crack bridging resulting in brittle failure ( Maghsoudi-Ganjeh et al, 2020 ). In compression, dehydrated bone cannot permit sliding between the mineral crystals in the extrafibrillar matrix and debonding between the extrafibrillar matrix and mineralized collagen fibrils resulting in a stiffer but stronger tissue.…”