Non-Stoichiometric Amorphous Calcium Carbonate Forms in Macromolecular Condensates via Interphase Diffusion

Area of Science:

• Biomineralization
• Materials Science
• Chemical Engineering

Background:

• Transient amorphous phases are crucial precursors for crystalline material formation.
• Amorphous calcium carbonate (ACC) crystallization is often regulated by interactions with negatively charged macromolecules.
• Electrostatically driven formation of Ca-macromolecule dense phases is an understudied phenomenon influencing ACC formation.

Purpose of the Study:

• To investigate the role of Ca-macromolecule condensates formed via liquid-liquid phase separation (LLPS) in controlling metastable ACC formation.
• To demonstrate how diffusion-based mass transport within these condensates influences ACC characteristics.
• To explore the potential for regulating mineralization through controlled transient phases.

Main Methods:

• Utilized liquid-liquid phase separation (LLPS) to form Ca-macromolecule condensates.
• Investigated diffusion-based mass transport of carbonate into these dense droplets.
• Analyzed the composition and stability of the resulting amorphous calcium carbonate (ACC) phases.

Main Results:

• Ca-macromolecule condensates formed via LLPS effectively control metastable ACC formation.
• ACC within condensates forms gradually via carbonate diffusion, yielding non-stoichiometric compositions.
• Control over concentration gradients across the phase boundary allows fine-tuning of amorphous precursor composition and stability.

Conclusions:

• Ca-macromolecule condensates offer a novel mechanism for controlling mineralization processes.
• The ability to regulate transient amorphous phase formation provides new avenues for materials design.
• This approach enhances understanding of biomineralization pathways involving amorphous precursors.