Goloshchapov Dmitry, Buylov Nikita, Emelyanova Anna, Ippolitov Ivan, Ippolitov Yuri, Kashkarov Vladimir, Khudyakov Yuri, Nikitkov Kirill, Seredin Pavel
Solid State Physics and Nanostructures Department, Voronezh State University, University sq.1, 394018 Voronezh, Russia.
Department of Pediatric Dentistry with Orthodontia, Voronezh State Medical University, Studentcheskaya st. 11, 394006 Voronezh, Russia.
Nanomaterials (Basel). 2021 Nov 16;11(11):3099. doi: 10.3390/nano11113099.
In this work, for the first time, the influence of the coordination environment as well as Ca and P atomic states on biomimetic composites integrated with dental tissue was investigated. Bioinspired dental composites were synthesised based on nanocrystalline calcium carbonate-substituted hydroxyapatite Ca4ICa6IIPO46-xCO3x+yOH2-y (nano-cHAp) obtained from a biogenic source and a set of polar amino acids that modelled the organic matrix. Biomimetic composites, as well as natural dental tissue samples, were investigated using Raman spectromicroscopy and synchrotron X-ray absorption near edge structure (XANES) spectroscopy. Molecular structure and energy structure studies revealed several important features related to the different calcium atomic environments. It was shown that biomimetic composites created in order to reproduce the physicochemical properties of dental tissue provide good imitation of molecular and electron energetic properties, including the carbonate anion CO and the atomic Ca/P ratio in nanocrystals. The features of the molecular structure of biomimetic composites are inherited from the nano-cHAp (to a greater extent) and the amino acid cocktail used for their creation, and are caused by the ratio between the mineral and organic components, which is similar to the composition of natural enamel and dentine. In this case, violation of the nano-cHAp stoichiometry, which is the mineral basis of the natural and bioinspired composites, as well as the inclusion of different molecular groups in the nano-cHAp lattice, do not affect the coordination environment of phosphorus atoms. The differences observed in the molecular and electron energetic structures of the natural enamel and dentine and the imitation of their properties by biomimetic materials are caused by rearrangement in the local environment of the calcium atoms in the HAp crystal lattice. The surface of the nano-cHAp crystals in the natural enamel and dentine involved in the formation of bonds with the organic matrix is characterised by the coordination environment of the calcium atom, corresponding to its location in the Ca position-that is, bound through common oxygen atoms with PO tetrahedrons. At the same time, on the surface of nano-cHAp crystals in bioinspired dental materials, the calcium atom is characteristically located in the Ca position, bound to the hydroxyl OH group. The features detected in the atomic and molecular coordination environment in nano-cHAp play a fundamental role in recreating a biomimetic dental composite of the natural organomineral interaction in mineralised tissue and will help to find an optimal way to integrate the dental biocomposite with natural tissue.
在这项工作中，首次研究了配位环境以及钙和磷的原子状态对与牙组织整合的仿生复合材料的影响。基于从生物源获得的纳米晶碳酸钙取代羟基磷灰石Ca4ICa6IIPO46-xCO3x+yOH2-y（纳米cHAp）和一组模拟有机基质的极性氨基酸合成了仿生牙科复合材料。使用拉曼光谱显微镜和同步加速器X射线吸收近边结构（XANES）光谱对仿生复合材料以及天然牙组织样本进行了研究。分子结构和能量结构研究揭示了与不同钙原子环境相关的几个重要特征。结果表明，为再现牙组织的物理化学性质而制备的仿生复合材料能够很好地模拟分子和电子能量性质，包括碳酸根阴离子CO以及纳米晶体中的原子Ca/P比。仿生复合材料的分子结构特征在很大程度上继承自纳米cHAp及其制备过程中使用的氨基酸混合物，并且是由矿物和有机成分之间的比例引起的，这与天然牙釉质和牙本质的组成相似。在这种情况下，违反纳米cHAp化学计量比（天然和仿生复合材料的矿物基础）以及在纳米cHAp晶格中包含不同分子基团，不会影响磷原子的配位环境。天然牙釉质和牙本质在分子和电子能量结构上观察到的差异以及仿生材料对其性质的模拟是由HAp晶格中钙原子局部环境的重排引起的。参与与有机基质形成键的天然牙釉质和牙本质中纳米cHAp晶体的表面，其特征在于钙原子的配位环境，这与它在Ca位置的位置相对应，即通过共同的氧原子与PO四面体结合。同时，在仿生牙科材料中纳米cHAp晶体表面，钙原子典型地位于Ca位置，并与羟基OH基团结合。在纳米cHAp中检测到的原子和分子配位环境特征在重建矿化组织中天然有机-矿物相互作用的仿生牙科复合材料中起着重要作用，并将有助于找到使牙科生物复合材料与天然组织整合的最佳方法。
