标题： 精确的力场参数和pH分辨的表面模型用于羟基磷灰石以理解结构、力学、水合和生物界面 显示英文标题

标题： Accurate Force Field Parameters and pH Resolved Surface Models for Hydroxyapatite to Understand Structure, Mechanics, Hydration, and Biological Interfaces

摘要： 骨和牙齿的矿化涉及生物分子与羟基磷灰石之间的相互作用。 相关的复杂界面和过程在1到100纳米尺度上使用现有的实验室技术难以分析，而以前的原子模拟模型在化学键、表面化学和界面相互作用的表示方面存在局限。 本研究引入了一个精确的力场以及pH分辨的羟基磷灰石表面模型，以定量地表示化学键、结构、表面、界面和机械性能。 与早期模型相比，其准确性提高了几个数量级，从而有助于对无机-生物组装进行定量监测。 该力场被整合到CHARMM、AMBER、OPLS-AA、PCFF和INTERFACE力场中，以实现任何成分和离子强度的磷酸盐-生物系统的现实模拟。 具体而言，参数再现了晶格常数（偏差小于0.5%）、红外光谱、解理能、在水中的浸润能（偏差小于5%）以及弹性常数（偏差小于10%）的羟基磷灰石，与实验结果相比。 矿物、水和有机化合物之间的相互作用通过力场中的标准组合规则表示，无需额外的可调参数，并且已被证明具有定量准确性。 基于广泛的实验数据，引入了常见（001）、（010）、（020）、（101）晶面和纳米晶体的表面模型，作为pH的函数。 描述了关于表面和浸润能、水界面结构、密度剖面和表层溶解的新见解。 可以分析肽、药物和矿化的特定结合机制，并且该力场还可扩展到取代和缺陷的磷酸盐以及其它磷酸钙相。 显示英文摘要

摘要： Mineralization of bone and teeth involves interactions between biomolecules and hydroxyapatite. Associated complex interfaces and processes remain difficult to analyze at the 1 to 100 nm scale using current laboratory techniques, and prior models for atomistic simulations are limited in the representation of chemical bonding, surface chemistry, and interfacial interactions. This work introduces an accurate force field along with pH-resolved surface models for hydroxyapatite to represent chemical bonding, structural, surface, interfacial, and mechanical properties in quantitative agreement with experiment. The accuracy is orders of magnitude higher in comparison to earlier models to facilitate quantitative monitoring of inorganic-biological assembly. The force field is integrated into the CHARMM, AMBER, OPLS-AA, PCFF, and INTERFACE force fields to enable realistic simulations of apatite-biological systems of any composition and ionic strength. Specifically, the parameters reproduce lattice constants (<0.5% deviation), IR spectrum, cleavage energies, immersion energies in water (<5% deviation), and elastic constants (<10% deviation) of hydroxyapatite in comparison to experiment. Interactions between mineral, water, and organic compounds are represented by standard combination rules in the force field without additional adjustable parameters and shown to achieve quantitative accuracy. Surface models for common (001), (010), (020), (101) facets and nanocrystals are introduced as a function of pH on the basis of extensive experimental data. New insight into surface and immersion energies, the structure of aqueous interfaces, density profiles, and superficial dissolution is described. Mechanisms of specific binding of peptides, drugs, and mineralization can be analyzed and the force field is extensible to substituted and defective apatites as well as to other calcium phosphate phases.