Makshakova Olga N, Gafurov Marat R, Goldberg Margarita A
Kazan Institute of Biochemistry and Biophysics, Federal Research Center Kazan Scientific Center of Russian Academy of Sciences, 420111 Kazan, Russia.
Institute of Physics, Kazan Federal University, 420008 Kazan, Russia.
Materials (Basel). 2022 Dec 17;15(24):9046. doi: 10.3390/ma15249046.
Hydroxyapatite (HA) with a stoichiometry composition of Ca(PO)(OH) is widely applied for various biomedical issues, first of all for bone defect substitution, as a catalyst, and as an adsorbent for soil and water purification. The incorporation of foreign ions changes the acid-base relation, microstructure, porosity, and other properties of the HA materials. Here, we report the results of calculations of the density functional theory and analyze the possibility of two foreign ions, CO and Mg, to be co-localized in the HA structure. The Na was taken into account for charge balance preservation. The analysis revealed the favorable incorporation of CO and Mg as a complex when they interact with each other. The energy gain over the sole ion incorporation was pronounced when CO occupied the A position and Mg was in the Ca(2) position and amounted to -0.31 eV. In the most energy-favorable complex, the distance between Mg and the O atom of carbonate ion decreased compared to Mg…O distances to the surrounding phosphate or hydroxide ions, and amounted to 1.98 Å. The theoretical calculations agree well with the experimental data reported earlier. Understating the structure-properties relationship in HA materials varying in terms of composition, stoichiometry, and morphology paves the way to rational designs of efficient bio-based catalytic systems.
化学计量组成为Ca(PO)(OH)的羟基磷灰石（HA）被广泛应用于各种生物医学问题，首先用于骨缺损替代、作为催化剂以及作为土壤和水净化的吸附剂。外来离子的掺入改变了HA材料的酸碱关系、微观结构、孔隙率和其他性质。在此，我们报告密度泛函理论的计算结果，并分析两种外来离子CO和Mg在HA结构中共定位的可能性。考虑了Na以保持电荷平衡。分析表明，当CO和Mg相互作用时，它们作为一种络合物能很好地掺入。当CO占据A位且Mg位于Ca(2)位时，与单独掺入离子相比，能量增益显著，达到-0.31 eV。在能量最有利的络合物中，Mg与碳酸根离子的O原子之间的距离与Mg与周围磷酸根或氢氧根离子的Mg…O距离相比减小，为1.98 Å。理论计算与先前报道的实验数据吻合良好。了解HA材料在组成、化学计量和形态方面变化的结构-性能关系为高效生物基催化系统的合理设计铺平了道路。
