Anisotropic diffusion of water molecules in hydroxyapatite nanopores

Prakash, Muthuramalingam, Lemaire, Thibault, Caruel, Matthieu, Lewerenz, Marius, de Leeuw, Nora H. ORCID: https://orcid.org/0000-0002-8271-0545, Di Tommaso, Devis and Naili, Salah 2017. Anisotropic diffusion of water molecules in hydroxyapatite nanopores. Physics and Chemistry of Minerals 44 (7) , pp. 509-519. 10.1007/s00269-017-0878-1

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Abstract

New insights into the dynamical properties of water in hydroxyapatite (HAP) nanopores, a model sys- 8 tems for the fluid flow within nano-size spaces inside the collagen-apatite structure of bone, were obtained from 9 molecular dynamics simulations of liquid water confined between two parallel HAP surfaces of different sizes 10 (20 Å ≤ H ≤ 240 Å). Calculations were conducted using a core-shell interatomic potential for HAP together with 11 the extended simple point charge model for water. This force field gives an activation energy for water diffusion 12 on the HAP surface that is in excellent agreement with available experimental data. The dynamical properties 13 of water within the HAP nanopores were quantified in terms of the second-order water diffusion tensor. Results 14 indicate that water diffuse anisotropically within the HAP nanopores with the solvent molecules moving parallel 15 to the surface twice as fast as the perpendicular direction. This unusual dynamic behaviour is linked to the strong 16 polarizing effect of calcium ions, and the synergic interactions between the water molecules in the first hydration 17 layer of HAP with the calcium, hydroxyl and phosphate ions, which facilitate the flow of water molecules in the 18 directions parallel to the HAP surface.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Uncontrolled Keywords:	Hydroxyapatite · Water Confinement · Molecular Dynamics · Hydrogen Bonding · Anisotropic Diffusion
Publisher:	Springer Verlag
ISSN:	0342-1791
Date of First Compliant Deposit:	7 February 2017
Date of Acceptance:	30 January 2017
Last Modified:	07 Nov 2023 02:58
URI:	https://orca.cardiff.ac.uk/id/eprint/98119

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