Polymer Mediated Nucleation of Minerals: A Molecular Dynamics Study

Biomineralization creates complex structures with advantageous properties, such as the superior toughness seen in nacre. In biomineral nucleation, calcium carbonate or calcium phosphate ions are directed by organic macromolecules, often leading to the growth of thermodynamically unfavorable polymorphs and/or specifically shaped crystals that contribute to the materials’ properties. To investigate how macromolecules guide crystal formation in complex biological systems, we probed the pre-nucleation nanoscale interactions in a simplified computational model that may govern overall precipitation and crystallization. We performed atomistic molecular dynamics simulations of calcium carbonate solution with charged polymers as analogs to the proteins that have been shown to influence crystallization. By analyzing resulting polymer and ion configurations in this system, we found that ion aggregate size and order are increased by the polymer’s presence, and this effect is a function of ion concentration and polymer properties such as hydrophobicity, chain flexibility, and charge.