Adsorption of Aspartate Derivatives to Calcite Surfaces in Aqueous Environment,Crystal Growth & Design

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Adsorption of Aspartate Derivatives to Calcite Surfaces in Aqueous Environment
Crystal Growth & Design ( IF 3.2 ) Pub Date : 2020-03-30 , DOI: 10.1021/acs.cgd.0c00061
Robert Stepić _{1,

2} , Lara Jurković ₃ , Ksenia Klementyeva ₂ , Marko Ukrainczyk ₃ , Matija Gredičak ₄ , David M. Smith ₁ , Damir Kralj ₃ , Ana-Sunčana Smith _{1,

2}

Affiliation

In many living organisms, biomolecules interact favorably with various surfaces of calcium carbonate. In this work, we considered the interactions of aspartate (Asp) derivatives, as models of complex biomolecules, with calcite. Using kinetic growth experiments, we 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 a flat (104) calcite surface is used 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.

中文翻译：

水环境中天冬氨酸衍生物对方解石表面的吸附

在许多生物中，生物分子可以与碳酸钙的各种表面发生良好的相互作用。在这项工作中，我们考虑了作为复杂生物分子模型的天冬氨酸（Asp）衍生物与方解石的相互作用。使用动力学生长实验，我们研究了Asp，Asp ₂和Asp ₃对方解石生长的抑制作用这需要确定逐步固定的生长机制，并评估这三种物质与方解石晶体的吸附常数和结合自由能。将后者的值与从完全原子分子动力学模拟获得的自由能曲线进行比较。当在模型中使用平坦的方解石表面（104）时，结合能的测量趋势很难重现。但是，由包含带有边缘和角的孤岛的表面组成的更逼真的模型会产生结合能，与实验相比非常好。出人意料的是，我们发现大多数结合方式都涉及带正电荷的铵基。此外，虽然也经常观察到带负电荷的羧酸酯基的结合，它总是由相等或更多数量的羧酸盐的水溶液溶剂化来平衡。在所有方解石特征（包括边角）上都观察到了这些影响，后者与Asp衍生物的主要亲和力有关。由于这些特征恰好也是晶体生长的活性位点，因此实验和理论结果强烈指出了一种生长抑制机制，其中这些位点被封闭，阻止了溶解离子的进一步附着并阻止了进一步的生长。

更新日期：2020-03-30

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