Molecular Dynamics modelling of Bone Tissue

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At the nano-scale, i.e. near molecular level, bone consist of tiny mineral platelets located within a matrix of collagen (i.e. a polymer). The mechanical properties of bones as perceived at the macroscale, notably the strength of bone, is affected by changes in the collagen, the mineral or the interaction between the collagen and the mineral. Conditions that cause changes in molecular scale structures and thus ultimately bone fractures include: ageing, osteoporosis, rickets in children and osteomalacia in adults, effect of fracture preventive drugs as well as pollution (lead is known to accumulate in bone). These conditions present a huge financial burden on public health systems and devastating consequences for individuals. Developments in experimental techniques are increasingly allowing a description of the structural changes at the molecular scale of bone and the structural changes due to the conditions mentioned above can be described (although still a field at the forefront of research). However, the effect of these structural changes on the mechanics (failure) at the scale of the collagen and mineral is poorly understood (and thus the fundamental causes of failure at a larger scale also remains poorly understood). A key reason for the challenge is that traditional engineering methods investigating failure are based on the accumulated average mechanical response of millions of molecules. To understand the mechanical behaviour between the molecular scale structures of bone, the molecular forces (electrostatic interactions) acting at this scale need to be considered. Molecular dynamics simulations provide a (now reasonably well-developed) method, which is ideally placed to investigate these fundamental issues but are rarely used for the purposes of investigating mechanical failure and even more rarely for investigations of bone properties and the origins of the mechanisms governing their failure.This project aims to develop a rigorous method based on molecular dynamics modelling for the purposes of investigating bone nano-scale mechanical behaviour. The develop method, and its link to the macroscopic behaviour of the tissue, will be used to address one or several of the mentioned conditions (ageing, osteoporosis etc).