Abstract
Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO3 particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO3 formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein.
Highlights
Calcium carbonate is an important biogenic mineral used by nature as an inorganic component in tissues and exoskeletons of many mineralizing organisms [1,2,3]
Zhao and co-workers [43] demonstrated that calcium carbonate crystals interacted with the sericin protein to form CaCO3 /protein clusters, which was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis
The results indicated that in the presence of lysozyme, the shape, and morphology of the crystals were the same as those in the sample without the proteins
Summary
Calcium carbonate is an important biogenic mineral used by nature as an inorganic component in tissues and exoskeletons of many mineralizing organisms [1,2,3]. Calcium carbonate in particular, are routinely used as templates for the fabrication of hollow multilayered microcapsules [6]. This fascination with biogenic minerals results in a need to control the factors associated with the formation of these materials, such as size distribution, morphology, and stability of templates [4,6]. Calcium carbonate exists in many forms, including hydrates (amorphous calcium carbonates; ACC) and anhydrates (calcite, vaterite, and aragonite) [7,8] Among these forms, calcite is the most thermodynamically stable, and most of the calcium carbonate in nature occurs in this form. Vaterite is the least stable of the three structures of anhydrous crystalline CaCO3 , but it plays an important role in calcium carbonate
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