Effect of nano-scale constraint on the mechanical behaviour of osteopontin–hydroxyapatite interfaces

Abstract

In many biological materials, the interfacial behaviour between constituents such as protein and minerals greatly contributes to the overall mechanical behaviour. However, the governing mechanisms, in particular at small material length scales, have not been clearly understood. This paper presents a molecular dynamics (MD) study of the mechanical behaviour of osteopontin (OPN) and hydroxyapatite (HA) interfaces under different geometrical constraints. The results indicate that some OPN residues are attracted to the HA layers during loading. The formation of new interfacial bonds leads to a stick-slip type motion of the OPN peptides along the HA surfaces, resulting in high pulling force and energy dissipation. The attractive interaction energy and energy dissipation generally increase with reducing the gap distance between the HA layers, demonstrating a significant nano-scale constraint effect.