Nanoparticulate amorphous calcium carbonate (ACC) is the initial and highly unstable phase in the crystallization of crystalline calcium carbonate, one of the most abundant minerals in its rock form (mainly as calcite and aragonite crystals). Crystalline calcium carbonate is the main component of seashells, mollusks, eggs etc. It was discovered that various marine creatures have the ability to produce and temporarily stabilize ACC as a biomineral that crystallizes toward the end of the exoskeleton building process.
This article describes the stabilization of ACC produced and stored by the Cherax quadricarinatus – an Australian freshwater crayfish species. The Cherax quadricarinatus stabilizes ACC using an organic matrix of phosphoproteins in gastroliths that are formed on both sides of its stomach wall. These phosphoproteins have high calcium binding capacity due to their phosphate group, which helps them form a matrix that prevents the ACC from crystallizing. This unique structure allows the Cherax quadricarinatus to grow a new exoskeleton within mere 72 hours thanks to high bioavailability and solubility of the ACC stored in its gastroliths.
Based on the above, Amorphical has developed a synthetic process of producing stable ACC. Stabilization is essential because it allows production of large quantities of ACC that remains stable over time and can be used for bio-medical needs.
The study establishes 2 crucial phenomena that lead to a broad range of Amorphical’s technology and therapeutic advancements:
- Phosphoproteins have high binding capacity for calcium at the surface of ACC particles, allowing their stabilization.
- Single phosphoamino acids can stabilize ACC in a process similar to the one used by marine creatures. The binding of the phosphoamino acids to the surface and within the molecular structure of the nanoparticle is a suitable approach for achieving the ACC stabilization, without the need for large and expensive protein-based reagents.
“Stabilization of amorphous calcium carbonate by phosphate rich organic matrix proteins and by single phosphoamino acids“, Bentov, S., Weil, S., Glazer, L., Sagi, A. & Berman, A. J Struct Biol 171, 207-15 (2010)