title: Molecular and intermolecular effects in collagen fibril mechanics: a multiscale analytical model compared with atomistic and experimental studies.
abstract: Both atomistic and experimental studies reveal the dependence of collagen fibril mechanics on biochemical and biophysical features such as, for instance, cross-link density, water content and protein sequence. In order to move toward a multiscale structural description of biological tissues, a novel analytical model for collagen fibril mechanics is herein presented. The model is based on a multiscale approach that incorporates and couples: thermal fluctuations in collagen molecules; the uncoiling of collagen triple helix; the stretching of molecular backbone; the straightening of the telopeptide in which covalent cross-links form; slip-pulse mechanisms due to the rupture of intermolecular weak bonds; molecular interstrand delamination due to the rupture of intramolecular weak bonds; the rupture of covalent bonds within molecular strands. The effectiveness of the proposed approach is verified by comparison with available atomistic results and experimental data, highlighting the importance of cross-link density in tuning collagen fibril mechanics. The typical three-region shape and hysteresis behavior of fibril constitutive response, as well as the transition from a yielding-like to a brittle-like behavior, are recovered with a special insight on the underlying nanoscale mechanisms. The model is based on parameters with a clear biophysical and biochemical meaning, resulting in a promising tool for analyzing the effect of pathological or pharmacological-induced histochemical alterations on the functional mechanical response of collagenous tissues.
authors.affiliation: Institute of Continuum Mechanics, Leibniz Universität Hannover, Appelstraße 11, 30167, Hannover, Germany. marino@ikm.uni-hannover.de.
authors.forename: Michele
authors.initials: M
authors.lastname: Marino
mesh_terms: D001696:Biomechanical Phenomena; D004548:Elasticity; D024022:Fibrillar Collagens / Q000378:metabolism*; D008954:Models, Biological
chemical_list: D024022:Fibrillar Collagens
keywords: Cross-link density; Elasto-damage response; Hysteresis behavior; Mechanics of collagen fibrils; Multiscale modeling