Soft Nanoconfinement Nucleates and Stabilizes Ultrasmall Amorphous Calcium Carbonate from Aggregation

Journal Article · Fri Sep 26 00:00:00 UTC 2025 · Crystal Growth & Design

DOI: https://doi.org/10.1021/acs.cgd.4c01555 · OSTI ID:3374367

Wang, Ying; Zhu, Yaguang; Zuo, Xiaobing ; He, Lilin; Jun, Young-Shin

Organisms use soft confinement structures, such as vesicles and compartments, to direct the nucleation of calcium carbonate (CaCO3) and its subsequent processes during biomineralization. Despite recent efforts elucidating confinement’s effects on CaCO3 polymorph selection, we still poorly understand how the size and distribution of CaCO3 are controlled within soft confinement. Here, using a size-controlled nanoemulsions system made from isooctane, Span 80, Tween 80, and aqueous solutions, we studied CaCO3 formation in soft confinement. Small angle X-ray scattering (SAXS) confirmed that a 72 nm aqueous core in nanoemulsions served as the confined space for CaCO3 formation. Unlike the ~ 50 nm CaCO3 particles that formed in the unconfined solution, small angle neutron scattering (SANS) and transmission electron microscope (TEM) showed that ultrasmall and amorphous calcium carbonate precipitated within soft confinement and did not exhibit any aggregation/coalescence of nanoparticles even after 24 hrs of reaction.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: American Chemical Society - Petroleum Research Fund; US Department of Energy; USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science - Office of Basic Energy Sciences
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 3374367
• Journal Information: Crystal Growth & Design, Journal Name: Crystal Growth & Design Journal Issue: 20 Vol. 25; ISSN 1528-7483
• Country of Publication: United States
• Language: English