Modelling the structure and properties of natural bone

This proposal will pioneer a new and exciting field in biomaterials chemistry and tissue engineering by exploiting new developments in computational materials science in order to achieve fundamental, quantitative understanding of the structure and properties of natural bone.
Natural bone material is a highly hierarchical protein-mineral composite, containing nano-sized mineral platelets (predominantly calcium phosphates), a protein matrix (predominantly collagen) and water. Although the mineral phase and the (wet) protein have very different properties - the mineral is stiff and brittle, while the protein is much softer and tougher - the composite combines the optimal properties of both components: the stiffness and the toughness. This unusual combination of material properties provides both rigidity and resistance against fracture, and an in-depth understanding of the underlying interfacial structures and properties would clearly help in the design of better composite materials.
The project will investigate at the atomic scale the interaction of the collagen protein with the phosphate mineral, which as the major constituent of natural bone tissue is an important component of various classes of composite bio-materials for bio-medical applications - hence an important issue in current bio-materials and life sciences research as well as being relevant to tissue engineering and medical implant technologies. The project will concentrate particularly on the molecular interaction of the collagen with surface features of the phosphate material and the templating role of the collagen in the apatite nucleation and growth process.
The outcome of the project will thus be a qualitative and quantitative understanding of the role of the protein and mineral phases in determining the properties of the composite bone material.

The manufacture of bio-compatible materials for bone replacement is currently a central theme in the fields of bio-medicine and tissue engineering research. Natural sources of bone graft material are compromised by availability and cost, both from the individual patient as autograft and from other donors as allograft. The appropriate material and structural properties of the graft for the donor sites are poorly defined. However, even well-controlled in vitro experiments into the behaviour and response of these complex materials to the biological environment are complicated. Furthermore, both in vivo studies and clinical trials are expensive and should be preceded by appropriate screening to comply with ethical justification. Thus, our understanding of how the macroscopic behaviour is influenced by processes at the molecular level is often limited, which is where state-of-the-art computer modelling techniques come into their own. The understanding of the physical and chemical properties of bio-materials can now profit enormously from the rapid increase in the capabilities of atomistic computer modelling techniques. This project will therefore develop and exploit a range of powerful computational methods to investigate key aspects of the molecular-level structure and properties of natural bone material, as a requisite to the computational design of composite bio-materials for tissue repair and replacement.