Breakthrough in Nanoparticle Research: Understanding Amorphous Calcium Carbonate Formation

Researchers from the Technion-Israel Institute of Technology have made a significant discovery in the field of nanotechnology, shedding light on the mechanisms behind the formation of amorphous calcium carbonate (ACC) nanoparticles. Led by Hadar Shaked, the team used in situ synchrotron small-angle X-ray scattering to study the crystallization process of ACC particles. Their findings, published in the Proceedings of the National Academy of Sciences, reveal that a narrow size distribution of ACC nanoparticles is essential for macroscopic crystal formation. The research was supported by the Minerva Foundation and highlights the importance of pH and Mg2+ concentrations in controlling the kinetics and thermodynamics of Mg-ACC formation.

Key Takeaways:

• Crystallization by amorphous calcium carbonate (ACC) particle attachment (CPA) is a prevalent biomineralization mechanism among calcifying organisms.
• A narrow, controlled size distribution of ACC nanoparticles is essential for macroscopic crystal formation via CPA.
• The research demonstrated that synthetic magnesium-stabilized ACC (Mg-ACC) nanoparticles form with an exceptionally narrow size distribution near the spinodal line during liquid-liquid phase separation.
• A 2-order magnitude rise in nucleation kinetics was observed for a 0.1 pH increase, and a 6-order magnitude rise for a 10% Mg2+ decrease.
• The influence of Mg2+ on calcite biomineralization is well studied, but its effect on Mg-ACC formation and particle size distribution remained unexplored.
• The findings highlight the delicate interplay of pH and Mg2+ in controlling the kinetics and thermodynamics of Mg-ACC formation, significantly impacting particle size distribution.
• The research has been peer-reviewed and published in the Proceedings of the National Academy of Sciences.

Statistics:

• The study mentioned a 2-order magnitude rise in nucleation kinetics for a 0.1 pH increase.
• A 6-order magnitude rise in nucleation kinetics was observed for a 10% Mg2+ decrease.
• The particle size distribution narrowed by factors of 2 for a pH increase of merely 0.1 and by a factor of 3 for a 10% Mg2+ decrease.

Sources:

• Proceedings of the National Academy of Sciences, 2025;122(19) (National Academy of Sciences - www.nasonline.org/; Proceedings of the National Academy of Sciences - www.nasonline.org/publications/pnas/)
• Impact of Mg2+ and pH on amorphous calcium carbonate nanoparticle formation: Implications for biomineralization and ocean acidification.