Key Parameters for Size- and Shape-Controlled Synthesis of Vaterite Particles

Abstract

Calcium carbonate (CaCO3) has attracted scientific attention due to its essential role in both inorganic and bioorganic chemistry. Vaterite is the least thermodynamically stable CaCO3 polymorph and has elicited great interest as an advanced biomaterial for tissue engineering, drug delivery, and a broad range of personal care products. Numerous methods of vaterite particle synthesis with different sizes and morphologies have highlighted the submicron porous particles of spherical or ellipsoidal shape as the most useful ones. In this regard, the current study is aimed at development of a reliable method for synthesis of such structures. Herein, submicron vaterite particles are synthesized by dropwise precipitation from saturated sodium carbonate and calcium chloride solutions in the presence of ethylene glycol while manipulating the concentration ratios of reagents. We demonstrate that our novel technique named “dropwise precipitation” leads to changing calcium concentrations in the reaction solution at each moment affecting the crystallization process. The proposed technique allows routine obtainment of vaterite particles of a required shape, either spherical or ellipsoidal, and a controlled size in the range from 0.4 to 2.7 μm and (0.4 × 0.7) to (0.7 × 1.1) μm, respectively. The key parameters influencing the size, shape, and percent of vaterite fraction for synthesized CaCO3 particles are discussed.

Gold Nanoparticle-Coated Microspheres for Enhancing Immunosensor Detection of Hepatitis B Virus Surface Antibody

“…Presence of ethylene glycol and dropwise precipitation significantly reduced the diameter of CM from 7.86 ± 1.22 to 3.06 ± 0.95 μm, compared to CM prepared with no ethylene glycol. The results correspond to the previous report that demonstrated the effect of viscosity and dropwise precipitation on the calcium carbonate crystal shape and size [7]. It is noted that both sizes of CM are much smaller than the pore size of nitrocellulose membrane (15.0 μm), so CM should be able to diffuse through the device.…”

“…CM were then washed with 95% ethanol three times and dried in vacuum. To reduce the size of CM, dropwise precipitation was performed in a presence of ethylene glycol [7]. Initially, ethylene glycol was mixed with water in a ratio of 2:1 by volume to be used as a solvent to prepare both CaCl2 and Na2CO3 solutions.…”

“…It is noted that both sizes of CM are much smaller than the pore size of nitrocellulose membrane (15.0 μm), so CM should be able to diffuse through the device. For a membrane with smaller pore size, the percentage of ethylene glycol or dropping rate might be adjusted to obtain smaller size of CM [7]. For EDS spectra of CM, Fig.…”

Synthesis Methods and Favorable Conditions for Spherical Vaterite Precipitation: A Review

“…Stirrers applied in laboratories are usually mechanical and magnetic, although other types are also proposed, e.g., ultrasound or microwave [13,53]. Recently, a "dropwise precipitation" has been adopted to calcium carbonate precipitation [54]. In this method, a calcium ion solution is added in very small portions to a carbonate solution.…”

The Crystallization Process of Vaterite Microdisc Mesocrystals via Proto-Vaterite Amorphous Calcium Carbonate Characterized by Cryo-X-ray Absorption Spectroscopy

“…Vaterite crystals have been synthesized in aqueous solutions [13][14][15], alcohol-water mixed solvents [16,17], dimethyl formamide-water mixed 2 of 12 solvents [13,18], and non-aqueous solvents [19,20]. Vaterite crystals were successfully synthesized in the presence of additives such as proteins [21], peptides [22], amino acids [23], and polyalcohols [24].…”