ChemRxiv
These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
1/1
0/0

On the Adsorption of Aspartate Derivatives to Calcite Surfaces in Aqueous Environment

preprint
submitted on 09.01.2020 and posted on 09.01.2020 by Robert Stepic, Lara Jurković, Ksenia Klementyeva, Marko Ukrainczyk, Matija Gredičak, David Matthew Smith, Damir Kralj, Ana-Sunčana Smith
In many living organisms, biomolecules interact favorably with various surfaces of calcium carbonate. In this work, we have considered the interactions of aspartate (Asp) derivatives, as models of complex biomolecules, with calcite. Using kinetic growth experiments, we have investigated the inhibition of calcite growth by Asp, Asp2 and Asp3.This entailed the determination of a step-pinning growth regime as well as the evaluation of the adsorption constants and binding free energies for the three species to calcite crystals. These latter values are compared to free energy profiles obtained from fully atomistic molecular dynamics simulations. When using a flat (104) calcite surface in the models, the measured trend of binding energies is poorly reproduced. However, a more realistic model comprised of a surface with an island containing edges and corners, yields binding energies that compare very well with experiments. Surprisingly, we find that most binding modes involve the positively charged, ammonium group. Moreover, while attachment of the negatively charged carboxylate groups is also frequently observed, it is always balanced by the aqueous solvation of an equal or greater number of carboxylates. These effects are observed on all calcite features including edges and corners, the latter being associated with dominant affinities to Asp derivatives. As these features are also precisely the active sites for crystal growth, the experimental and theoretical results point strongly to a growth inhibition mechanism whereby these sites become blocked, preventing further attachment of dissolved ions and halting further growth.

History

Email Address of Submitting Author

robertstepic5@gmail.com

Institution

Ruder Boskovic Institute

Country

Croatia

ORCID For Submitting Author

0000-0003-4486-7653

Declaration of Conflict of Interest

no conflict of interest

Exports

Logo branding

Exports