Mechanics of Mineralized Collagen Fibrils upon Transient Loads

Mario Milazzo, Gang Seob Jung, Serena Danti, Markus J. Buehler

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Collagen is a key structural protein in the human body, which undergoes mineralization during the formation of hard tissues. Earlier studies have described the mechanical behavior of bone at different scales, highlighting material features across hierarchical structures. Here we present a study that aims to understand the mechanical properties of mineralized collagen fibrils upon tensile/compressive transient loads, investigating how the kinetic energy propagates and it is dissipated at the molecular scale, thus filling a gap of knowledge in this area. These specific features are the mechanisms that nature has developed to passively dissipate stress and prevent structural failures. In addition to the mechanical properties of the mineralized fibrils, we observe distinct nanomechanical behaviors for the two regions (i.e., overlap and gap) of the D-period to highlight the effect of the mineralization. We notice decreasing trends for both wave speeds and Young's moduli over input velocity with a marked strengthening effect in the gap region due to the accumulation of the hydroxyapatite. In contrast, the dissipative behavior is not affected by either loading conditions or the mineral percentage, showing a stronger damping effect upon faster inputs compatible to the bone behavior at the macroscale. Our results offer insights into the dissipative behavior of mineralized collagen composites to design and characterize bioinspired composites for replacement devices (e.g., prostheses for sound transmission or conduction) or optimized structures able to bear transient loads, for example, impact, fatigue, in structural applications.

Original languageEnglish
Pages (from-to)8307-8316
Number of pages10
JournalACS Nano
Volume14
Issue number7
DOIs
StatePublished - Jul 28 2020
Externally publishedYes

Funding

This work was supported by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement COLLHEAR no. 794614. G.S.J. and M.J.B. acknowledge additional support from ONR (N000141612333) and AFOSR (FATE MURI FA9550-15-1-0514) as well as NIH U01HH4977, U01EB014976, and U01EB016422.

Keywords

  • biocomposites
  • bone
  • collagen
  • molecular dynamics
  • tissue engineering
  • wave propagation

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