Growth of calcium carbonate mediated by slowly released alginate

Abstract

The presence of additives has demonstrated strong effects on the crystallization and morphology of calcium carbonate (CaCO 3 ). To understand the mediating function of alginate on the growth of CaCO 3 , we design a novel method to add alginate molecules and inorganic ions mildly and continuously to the mineralization system: a Ca-alginate gel is used as a slow-releasing source of calcium ions and alginate molecules; the gel is gradually broken down by the diffusion of CO 2 to the solution, inducing the slow release of Ca 2+ and alginate molecules. The slowly released alginate is involved in the nucleation and growth of CaCO 3 , in the form of micro-sized lens-like particles with a vaterite polymorph and composed of fused nanoparticles. With the increasing reaction time, the lenslike CaCO 3 particles gradually develop into a hollow structure and finally turn into ring-shaped CaCO 3 , in which the polymorph of CaCO 3 remains vaterite. The formation of the lens-like particles is the result of the partially-oriented aggregation of primary nanoparticles mediated by alginate. The further evolution of the morphology to ring-shaped particles is due to a dissolution-recrystallization process as well as Ostward ripening.

Combined effect of ion concentration and functional groups on surface chemistry modulated CaCO3 crystallization

“…According to Wulff's rule, 41 the shape of crystals is affected by the different surface energy of surfaces, which is influenced by different physical and chemical properties of the surfaces. 3,[7][8][9][10]42,43 In our study, all the surfaces are selfassembled on the same metal with the same chain length of alkylthiols. The similar densities suggest same patterns of terminated functional groups, consist of the (!3 6 !3) R30u structure.…”

The Intrinsic Ability of Silk Fibroin to Direct the Formation of Diverse Aragonite Aggregates

“…These matrix proteins are believed to interact both with β ‐chitin fibrils and growing crystals so as to translate the orientation of chitin to the minerals 6. Numerous efforts have been undertaken to identify and characterize the matrix proteins present in the nacreous tables2, 7, 11, 12 and to mimic the growth process of aragonite minerals in vitro through the involvement of various natural and synthesized additives 13–17. However, this process remains elusive due to the fact that it is difficult to investigate the molecular‐level interaction between proteins and minerals, and to understand the importance of protein sequences and conformation in controlling the structure of biominerals, as well as the role of other possible proteins involved in the bimineralization process 14, 18…”

Green Synthesis of Calcium Carbonate With Unusual Morphologies in the Presence of Fruit Extracts

“…Alginate and chitosan are both natural polysaccharides. Alginate and chitosan were frequently employed as a substrate to mimic biomineralization [11][12][13][14][15][16] . The extracted polysaccharides were also used to mimic biomineralization as matrix.…”