Polyamines Promote Aragonite Nucleation and Generate Biomimetic Structures. Issue 1 (20th November 2022)

• Record Type: Journal Article
• Authors: Nahi, Ouassef; Kulak, Alexander N.; Zhang, Shuheng; He, Xuefeng; Aslam, Zabeada; Ilett, Martha A.; Ford, Ian J.; Darkins, Robert; Meldrum, Fiona C.
• Is Part Of: Advanced science. Volume 10:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-20
• Subjects: biomineralization -- calcium carbonate -- magnesium -- non‐classical crystallization -- polymorph; Science -- Periodicals; 505
• DOI: 10.1002/advs.202203759
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: Calcium carbonate biomineralization is remarkable for the ability of organisms to produce calcite or aragonite with perfect fidelity, where this is commonly attributed to specific anionic biomacromolecules. However, it is proven difficult to mimic this behavior using synthetic or biogenic anionic organic molecules. Here, it is shown that cationic polyamines ranging from small molecules to large polyelectrolytes can exert exceptional control over calcium carbonate polymorph, promoting aragonite nucleation at extremely low concentrations but suppressing its growth at high concentrations, such that calcite or vaterite form. The aragonite crystals form via particle assembly, giving nanoparticulate structures analogous to biogenic aragonite, and subsequent growth yields stacked aragonite platelets comparable to structures seen in developing nacre. This mechanism of polymorph selectivity is captured in a theoretical model based on these competing nucleation and growth effects and is completely distinct from the activity of magnesium ions, which generate aragonite by inhibiting calcite. Profiting from these contrasting mechanisms, it is then demonstrated that polyamines and magnesium ions can be combined to give unprecedented control over aragonite formation. These results give insight into calcite/aragonite polymorphism and raise the possibility that organisms may exploit both amine‐rich organic molecules and magnesium ions in controlling calcium carbonate polymorph. Abstract : Polyamines, including small molecules and polyelectrolytes, are shown to exert remarkable control over calcite/aragonite polymorphism, where they operate by an entirely different mechanism to magnesium ions and promote aragonite nucleation at exceptionally low concentrations. The aragonite crystals exhibit granular structures analogous to biogenic aragonite and growth via particle assembly yields stacks of aragonite platelets that resemble developing nacre.