Calcium carbonate formation in the presence of serum protein

A problem presented at the Canadian MMSG Toronto 2009.

Presented by:
Dr Jake Barralet (Faculty of Dentistry, McGill University)
Mr David Bassett (Faculty of Dentistry, McGill University)
JE Barralet, DC Bassett, S Bohun, CJ Breward, H Huang, M Morfin Ramírez, N Nigam, J Phillips, BS Tilley, M Tindall, J Wattis

Problem Description

Many species synthesise calcium carbonate for protective structures as well as components of aural organs. Various acidic proteins are found in many mineralized tissues such as bone, teeth and shells and also in ectopic mineralisation. They can inhibit or promote mineralisation as well as alter the phases of the mineral formed.

In experiments calcium carbonate is slowly precipitated via diffusion of the carbon dioxide gas into a well filled with calcium chloride solution with or without protein. In protein-free control experiments, the most stable form of calcium carbonate, calcite, is formed. However in the presence of protein, 200nm fibres of calcium carbonate formed that were self assembled in conical shapes, or as blade-like calcite crystals arranged in parallel bundles. In addition to these fibres, floating crystals of vaterite, the least stable crystalline form, were observed from which fibrous processes protruded into the liquid and it was from these fibrous processes that the fibre bundles and conical shapes appeared to grow.

Current explanations of these templated nanostructures are ‘hand-wavy’ and suggest that protein-mineral nanoclusters are self assembled at fibre tips and lack quantitative support. Can the study group do better?

Download the full problem description

Study Group Report

We propose a mechanism for the formation of calcium carbonate fibers and their assembly in the complex structures. We describe this process in two systems of partial differential equations. We aim to simulate the growth of these crystals in order to understand the effect of the concentrations and diffusion of the different elements and compounds that are present in the reaction, in the global regulator of the crystallization process.

Download the full report