Laboratory for Precipitation Processes, Ruđer Bošković Institute, P.O. Box 180, 10002, Zagreb, Croatia.
Department of Chemistry "Giacomo Ciamician", Alma Mater Studiorum-Universitá di Bologna, Via Selmi 2, 40126, Bologna, Italy.
Chemistry. 2019 Aug 9;25(45):10616-10624. doi: 10.1002/chem.201900691. Epub 2019 Apr 26.
The biomineralization of corals occurs under conditions of high and low supersaturation with respect to aragonite, which corresponds to day- or night-time periods of their growth, respectively. Here, in vitro precipitation of aragonite in artificial seawater was investigated at a high supersaturation, allowing spontaneous nucleation and growth, as well as at low supersaturation conditions, which allowed only the crystal growth on the deliberately introduced aragonite seeds. In either chemical systems, soluble organic matrix (SOM) extracted from Balanophyllia europaea (light sensitive) or Leptopsammia pruvoti (light insensitive) was added. The analyses of the kinetic and thermodynamic data of aragonite precipitation and microscopic observations showed that, at high supersaturation, the SOMs increased the induction time, did not affect the growth rate and were incorporated within aggregates of nanoparticles. At low supersaturation, the SOMs affected the aggregation of overgrowing crystalline units and did not substantially change the growth rate. On the basis of the obtained results we can infer that at high supersaturation conditions the formation of nanoparticles, which is typically observed in the skeleton's early mineralization zone may occur, whereas at low supersaturation the overgrowth on prismatic seeds observed in the skeleton fiber zone is a predominant process. In conclusion, this research brings insight on coral skeletogenesis bridging physicochemical (supersaturation) and biological (role of SOM) models of coral biomineralization and provides a source of inspiration for the precipitation of composite materials under different conditions of supersaturation.
珊瑚的生物矿化作用发生在方解石过饱和度高和低的条件下，分别对应于它们生长的白天和夜间时期。在这里，在高过饱和度下研究了人工海水中方解石的体外沉淀，允许自发成核和生长，以及在低过饱和度条件下，只允许在故意引入的方解石种子上进行晶体生长。在这两种化学体系中，均添加了从 Balanophyllia europaea（对光敏感）或 Leptopsammia pruvoti（对光不敏感）中提取的可溶性有机基质（SOM）。对方解石沉淀的动力学和热力学数据的分析以及微观观察表明，在高过饱和度下，SOM 会增加诱导时间，不会影响生长速率，并被包裹在纳米颗粒的聚集体中。在低过饱和度下，SOM 会影响过生长的晶状单元的聚集，但不会显著改变生长速率。根据获得的结果，我们可以推断出在高过饱和度条件下，可能会发生通常在骨骼早期矿化区观察到的纳米颗粒的形成，而在低过饱和度下，在骨骼纤维区观察到的棱柱形种子上的过生长是主要过程。总之，这项研究深入了解了珊瑚矿化的物理化学（过饱和度）和生物（SOM 作用）模型，为在不同过饱和度条件下沉淀复合材料提供了灵感。
