Formation and evolution of dense liquid phase of calcium (bi)carbonate

What role does dense liquid phase formation play in mineralization?

Bao Jin, Ying Chen, James De Yoreo, and their colleagues at Nanjing University, Pacific Northwest National Laboratory, and the University of Washington – Seattle published recent work using their Hummingbird Scientific in-situ liquid flow TEM sample holder to investigate the formation and solidification of a highly hydrated bicarbonate dense liquid phase (DLP) via liquid-liquid phase separation and subsequent transformation into hollow hydrated amorphous CaCO₃ particles.

a) Video showing the formation and growth of DLP droplets in liquid cell. b) Measured radius of three droplets labeled in (a). c) Video showing formation of branched and worm-like DLP network. d) Video showing evolution of DLP droplets into hollow hydrated amorphous CaCO₃ particles. Copyright © Battelle Memorial Institute and the Authors, under exclusive license to Springer Nature Limited 2024

Changes to morphology and growth rate were tracked using time-resolved transmission electron microscopy under various chemical conditions. The evolution of various ionic species were tracked using nuclear magnetic resonance (NMR), confirming the chemical mechanisms governing DLP formation and decomposition. Acidic proteins and polymers were found to extend the DLP lifetimes. Branched, worm-like DLP forms in the presence of CaCl₂ and NaHCO₃. The work reveals the effect of liquid-liquid separation into dense liquid phases on carbonate mineralization and will inform future optimization of biomineralizing systems.

Reference:

Biao Jin, Ying Chen, Harley Pyles, Marcel D. Baer, Benjamin A. Legg, Zheming Wang, Nancy M. Washton, Karl T. Mueller, David Baker, Gregory K. Schenter, Christopher J. Mundy, James J. De Yoreo, Nature Materials (2024) DOI: 10.1038/s41563-024-02025-5

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