Calcium oxalate occurs widely in kidney stones and among a variety of living organisms[1]. The presence of bio-polymers such as polyacrylate, polyaspartate or polyglutamate during the formation of calcium oxalate crystal has a great impact on the crystalline phase, morphology and growth rate[2-4]. In spite of advances in the experimental characterization of the influence that these bio-polymers exert on the crystallization of calcium rich biominerals, a full understanding of these processes on a molecular scale has not yet been accomplished. First principle molecular dynamics simulations offer a valuable tool to complement experimental investigations, thanks to the possibility to accurately describe the heterogeneous environment at interfaces, where polarization effects and specific hydrogen bond dynamics play a key role. We provide here a structural and dynamical characterization of the interfaces between calcium oxalate dihydrate(COD) (100) and (101) and water, which reveals differences in the structure of interfacial water and in the local coordination of calcium ions on the surface. Moreover we characterize the interaction between different surfaces of COD and biomolecules. As a first step we consider acetate as an analogue for the carboxylate group of glutamate side chains, and we estimate its binding structure and free energies on different COD surfaces at different coverage. Preferential binding of carboxylate to the (100) surface is found, providing a rational for recent experimental results on anisotropic growth of COD crystals in the presence of biopolymers[2]. These results also serve us to calibrate empirical models to study polymer-controlled crystal growth of calcium oxalate in large scale atomistic simulations.  [1]E.L. Prein and C. Frondel, J. Urol. 57, 949, 1947.[2]V. Fischer, K. Landfester and R. Munoz-Espi, Cryst. Growth Des. 11, 1880, 2011.[3]A. Thomas and et al., Chem. Eur. J. 18, 4000, 2012.[4]T. Jung, W.S. Kim, C.K. Choi, J. Cryst. Growth. 279, 154-162, 2005.

Understanding the crystal growth inhibition: Role of acetate at the calcium oxalate/water interfaces

248th National Meeting (2014)

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