The whole range of organic-inorganic hybrid materials are generally molded into specifically designed devices with fascinating properties that are precisely controlled. The mimicking of the processes involved in biomineralization may provide new approaches to the fabrication of specialized organic-inorganic hybrid materials. Recently, researchers found that the control over polymorphism, crystallographic orientation, and crystal organization are paramount in determining the properties of hybrid materials. In this article, the biomimetic synthesis of calcium carbonate, the most abundant biomineral, has been the main focus.

Biomimetic CaCO3 mineralization using designer molecules and interfaces

State of art of natural inhibitors of calcium carbonate scaling. A review article

Membrane distillation operated at high seawater concentration factors: Role of the membrane on CaCO3 scaling in presence of humic acid

Shape-controlled synthesis of calcium carbonate with specific polymorphs can be achieved by the assistance of organic additives. In this study, highly uniform nanosized calcium carbonate spheres were synthesized by a fast precipitation method in the presence of a simple polymer, poly(styrene sulfonate) (PSS). The polymorph of the synthesized calcium carbonate products changes from pure calcite in PSS-free reactions to vaterite in PSS-containing (1–50 g/L) reactions. The effect of PSS on the formation of vaterite can be attributed to the two aspects: decrease of driving force by reducing the interfacial energy, and phase stabilization effect caused by the adsorbed PSS. A higher PSS concentration (50 g/L) results in highly uniform vaterite nanospheres of 400–500 nm in diameter. Furthermore, PSS is found more effective to induce the formation of vaterite in the Ca2+-rich reaction condition (Ca2+: CO 3 2 -  = 5:1) than in the CO 3 2 - -rich conditions (Ca2+: CO 3 2 -  = 1:5). It has also been found that different mixing mode of the calcium and carbonate precursor solutions has a significant influence on the size distribution of the products. Finally, with a controlled anion-exchange method, the as-prepared vaterite nanospheres can be easily transformed to hollow hydroxyapatite spheres, which exhibit great potential to be used as the drug carriers due to their considerably high surface area and biocompatibility.

Fast precipitation of uniform CaCO3 nanospheres and their transformation to hollow hydroxyapatite nanospheres

Calcite precipitation from CO2–H2O–Ca(OH)2 slurry under high pressure of CO2

The influence of four calcium complexing substances, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA) and pyromellitic acid (PMA), on the crystal growth rate of the calcium carbonate polymorphs aragonite and calcite has been studied. Using a seeded constant supersaturation method supersaturation was maintained at 4 by keeping a constant pH of 8.5 through addition of sodium carbonate and calcium chloride solutions. The unique composition of each solution was calculated using chemical speciation. The growth rate was interpreted in terms of an overall growth rate. For both calcite and aragonite, the crystal growth rate is significantly reduced in the presence of the calcium complexing substances. The growth retarding effect depends on both the concentration and the polymorph. The relative crystal growth rate was correlated to the total complexing agent concentration using a Langmuir adsorption approach. Aragonite appeared fully covered for lower total concentrations than calcite. Furthermore, CIT very efficiently blocked aragonite growth contrary to what was observed for calcite. This is thought to be related to certain distinct features of the dominant aragonite crystal faces compared to the dominant calcite faces.

K. J. Westin

Papers

Crystal growth of aragonite and calcite in presence of citric acid, DTPA, EDTA and pyromellitic acid.

Nucleation of calcium carbonate in presence of citric acid, DTPA, EDTA and pyromellitic acid.

Precipitation of calcium carbonate in the presence of citrate and EDTA