title: Calcium carbonate nucleation driven by ion binding in a biomimetic matrix revealed by in situ electron microscopy.
abstract: The characteristic shapes, structures and properties of biominerals arise from their interplay with a macromolecular matrix. The developing mineral interacts with acidic macromolecules, which are either dissolved in the crystallization medium or associated with insoluble matrix polymers, that affect growth habits and phase selection or completely inhibit precipitation in solution. Yet little is known about the role of matrix-immobilized acidic macromolecules in directing mineralization. Here, by using in situ liquid-phase electron microscopy to visualize the nucleation and growth of CaCO3 in a matrix of polystyrene sulphonate (PSS), we show that the binding of calcium ions to form Ca-PSS globules is a key step in the formation of metastable amorphous calcium carbonate (ACC), an important precursor phase in many biomineralization systems. Our findings demonstrate that ion binding can play a significant role in directing nucleation, independently of any control over the free-energy barrier to nucleation.
authors.affiliation: 1] Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands [3] Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands [4] Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: Paul J M
authors.initials: PJ
authors.lastname: Smeets
authors.affiliation: Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Kang Rae
authors.initials: KR
authors.lastname: Cho
authors.affiliation: Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Ralph G E
authors.initials: RG
authors.lastname: Kempen
authors.affiliation: 1] Laboratory of Materials and Interface Chemistry and Soft Matter CryoTEM Unit, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands [2] Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Nico A J M
authors.initials: NA
authors.lastname: Sommerdijk
authors.affiliation: Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: James J
authors.initials: JJ
authors.lastname: De Yoreo
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization; D007477:Ions / Q000737:chemistry; D046911:Macromolecular Substances / Q000737:chemistry / Q000648:ultrastructure; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008903:Minerals / Q000737:chemistry; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D011137:Polystyrenes / Q000737:chemistry; D012996:Solutions
chemical_list: D007477:Ions; D046911:Macromolecular Substances; D008903:Minerals; D011137:Polystyrenes; D012996:Solutions; C003321:polystyrene sulfonic acid; D002119:Calcium Carbonate