Multiscale Characterization of Type I Collagen Fibril Stress–Strain Behavior under Tensile Load: Analytical vs. MD Approaches

Abstract

Type I collagen is one of the most important proteins in the human body because of its role in providing structural support to the extracellular matrix of the connective tissues. Understanding its mechanical properties was widely investigated using experimental testing as well as molecular and finite element simulations. In this work, we present a new approach for defining the properties of the type I collagen fibrils by analytically formulating its response when subjected to a tensile load and investigating the effects of enzymatic crosslinks on the behavioral response. We reveal some of the shortcomings of the molecular dynamics (MD) method and how they affect the obtained stress–strain behavior of the fibril, and we prove that not only does MD underestimate the Young’s modulus and the ultimate tensile strength of the collagen fibrils, but also fails to detect the mechanics of some stretching phases of the fibril. We prove that non-crosslinked fibrils have three tension phases: (i) an initial elastic deformation corresponding to the collagen molecule uncoiling, (ii) a linear regime related to the stretching of the backbone of the tropocollagen molecules, and (iii) a plastic regime dominated by molecular sliding. We also show that for crosslinked fibrils, the second regime can be subdivided into three sub-regimes, and we define the properties of each regime. We also prove, analytically, the alleged MD quadratic relation between the ultimate tensile strength of the fibril and the concentration of enzymatic crosslinks (β).

Knee joint biomechanics and cartilage damage prediction during landing: A hybrid MD-FE-musculoskeletal modeling

“…All MD simulations were performed using LAMMPS molecular dynamics software [ 36 ] ( Fig 1 ). Additional details about the developed model can be found in the S1 File and our prior works [ 18 , 24 , 37 , 38 ].…”

Three-Dimensional Mechanical Microenvironment Rescued the Decline of Osteogenic Differentiation of Old Human Jaw Bone Marrow Mesenchymal Stem Cells

“…It is widely distributed throughout the body in connective tissues such as joint ligaments and tendons 50 and has strong biomechanical properties that can be used for stretching. 51 By reviewing the literature, we chose rat tail collagen as the raw material for the hydrogel. 52 Rat tail collagen is type I collagen, which is an important component of the extracellular matrix, 53 and in addition, it is a natural culture medium that promotes cell adhesion in vitro.…”

“…It is one of the most important tissue proteins in the human body. It is widely distributed throughout the body in connective tissues such as joint ligaments and tendons and has strong biomechanical properties that can be used for stretching . By reviewing the literature, we chose rat tail collagen as the raw material for the hydrogel .…”