title: Characterization of the viscoelastic behavior of a simplified collagen micro-fibril based on molecular dynamics simulations.
abstract: Collagen fibril is a major component of connective tissues such as bone, tendon, blood vessels, and skin. The mechanical properties of this highly hierarchical structure are greatly influenced by the presence of covalent cross-links between individual collagen molecules. This study investigates the viscoelastic behavior of a collagen lysine-lysine cross-link based on creep simulations with applied forces in the range or 10 to 2000pN using steered molecular dynamics (SMD). The viscoelastic model of the cross-link was combined with a system composed by two segments of adjacent collagen molecules hence representing a reduced viscoelastic model for a simplified micro-fibril. It was found that the collagen micro-fibril assembly had a steady-state Young׳s modulus ranging from 2.24 to 3.27GPa, which is in agreement with reported experimental measurements. The propagation of longitudinal force wave along the molecule was implemented by adding a delay element to the model. The force wave speed was found to be correlated with the speed of one-dimensional elastic waves in rods. The presented reduced model with three degrees of freedom can serve as a building block for developing models of the next level of hierarchy, i.e., a collagen fibril.
authors.affiliation: Department of Mechanical Engineering, College of Engineering, Temple University, 1947N. 12th street, Philadelphia, PA 19122, USA. Electronic address: hossein.ghodsi@temple.edu.
authors.forename: Hossein
authors.initials: H
authors.lastname: Ghodsi
authors.affiliation: Department of Mechanical Engineering, College of Engineering, Temple University, 1947N. 12th street, Philadelphia, PA 19122, USA. Electronic address: kdarvish@temple.edu.
authors.forename: Kurosh
authors.initials: K
authors.lastname: Darvish
mesh_terms: D001696:Biomechanical Phenomena; D003094:Collagen / Q000737:chemistry*; D055119:Elastic Modulus; D056004:Molecular Dynamics Simulation
chemical_list: D003094:Collagen
keywords: Collagen micro-fibril; Creep simulations; Cross-link; Quasi-linear viscoelastic (QLV) theory; Steered molecular dynamics; Viscoelastic properties