Stable Amorphous CaCO₃ Microparticles with Hollow Spherical Superstructures Stabilized by Phytic Acid

Abstract

Amorphous CaCO3 (ACC) is stabilized by the presence of phytic acid, a natural inositol hexakisphosphate (IP6). Micrometer‐sized hollow spheres of ACC have been obtained (see Figure). The spheres are stable for at least three months in solution, which is equivalent to that described for more complex special biopolymers in biomineralization processes, and by far exceeds the previously known stability of ACC prepared in the presence of synthetic molecules.

Tailoring the shape of amorphous nanomaterials: recent developments and applications

“…This is because a variety of intermediates of the PAA-Ca 2+ -H 2 O complex coexist in the earlier stage of complexation; that is, the coordination of Ca 2+ ions with PAA is more random earlier in the reaction. Phytic acid is another effective inhibitor of the crystallization of ACC nanospheres fabricated using a gas-diffusion method, as described by Xu et al [43]. They also found that hydrated ACC can form on the exterior of anhydrous ACC and then grow at the expense of the dissolving internal anhydrous ACC particles, producing a hollow nanostructure.…”

“…Spherical structure is also favorable in terms of surface energy. Nanospheres are the most reported shape of amorphous materials in the last decade (see Table 1), and they can be composed of calcium carbonate (CaCO 3 ) [43][44][45][46][47], silicon (Si) [48][49][50][51][52], metals or their compounds [53][54][55][56][57][58][59][60][61]. CaCO 3 is abundant in the natural world, and a typical model system used to mimic the mineralization process of biominerals [43].…”

“…Because of their complex internal structure, the growth of amorphous nanomaterial is usually ruleless, resulting in irregular particles using solution approaches or thin films using deposition techniques as their conventional shape. Over the last decade, inorganic amorphous nanomaterials with a variety of novel shapes, with notable examples including spheres, wires, tubes, fibers, cubes, octahedra, polyhedra, flower-like spheres and arrays, which are summarized in spheres (hollow) CaCO 3 gas-diffusion solution method [43] spheres CaCO 3 solution method [44] spheres CaCO 3 solution method [45] spheres CaCO 3 solution method [46] spheres CaCO 3 solution method [47] spheres Si thermal decomposition [48] spheres Si solution method [49] spheres Si/Ti solution method [50] spheres Si:H thermal decomposition [51] spheres Si:H thermal decomposition [52] spheres Se solution method [53] spheres TiO 2 solution method [54][55][56] spheres (hollow) PbO-TiO 2 sol-gel method [57] spheres Co-B alloy solution method [58] spheres 2 solution method [80] nanoboxes Ni(OH) 2 solution method [81] nanocubes (hollow) Co(OH) 2 solution method [82] nanopolyhedra (hollow) CoS solution method [83] mesopores nanocubes ZnSnO 3 solution method and annealing [84] REVIEWS SCIENCE CHINA Materials Table 1, have been synthesized. In this review, we explain how these exquisite nanostructures can be obtained by a number of innovative methods.…”

Solubility and bioavailability of stabilized amorphous calcium carbonate

“…(6) Several techniques have been reported for the synthesis and stabilization of ACC, (4,7) but all known methods use either toxic materials or various organic polymers to stabilize ACC for more than 3 days. (7)(8)(9)(10)(11) To avoid use of such compounds, a novel method for synthetic production of stabilized ACC using phosphoaminoacids was developed recently (12) and was shown to stabilize ACC for more than 4 months under ambient conditions.…”

“…(10,13,14) In most cases, these organisms use calcium in the amorphous phase as a precursor for one of the crystalline phases. (15) In other instances, organisms construct specialized transient mineral storage sites composed of stabilized amorphous calcium carbonate embedded on an organic matrix comprising dense chitin fibers and proteins.…”