Nucleation of Calcium Carbonate as Polymorphic Crystals in the Presence of Lipid A-Diphosphate

Abstract

The well-defined structure of lipid A-diphosphate in aqueous solutions provides a way of observing the formation of calcium carbonate crystals. The crystals are either tetrahedral or rhombohedral calcite at a volume fraction of phi = 5.4 x 10 (-4) at pH 5.8 or the vaterite polymorph of CaCO(3) at a volume fraction of phi = 7.8 x 10 (-4) at pH 5.8. In both cases, nucleation, adsorption pH, and the shape-dependent template of lipid A-diphosphate control the formation of the calcite and vaterite.

Biomimetic Mineralization of CaCO3on a Phospholipid Monolayer: From an Amorphous Calcium Carbonate Precursor to Calcite via Vaterite

“…Lipids, proteins, and polysaccharides play vital roles in the crystallization of biominerals . For instance, lipids can guide the formation of a large variety of materials with controlled micro- and nanostructures through their ability to self-assemble, compartmentalize, and form templates and thus have attracted increasing attention with respect to understanding biomineralization and synthesizing new biomaterials. − In particular, phospholipids as the key membrane constituents of biological vesicles are commonly involved in delineating reaction compartments for the crystallization of biominerals, such as marine alga coccolith Emiliania huxleyi , the mineralizing tissues of vertebrates, and magnetosomes in magnetotactic bacteria. − In pursuing in vitro models, Mann et al used phospholipid unilamellar vesicles to study the membrane-mediated growth of iron oxide crystals. It was found that lipid vesicles not only acted as passive hosts to enclose mineralization reactions but also strongly influenced the growing inorganic phase through the molecular recognition of chemical, electrostatic, and chiral complementarity.…”

Mineralization of Lipid A-Phosphates in Three- and Two-Dimensional Colloidal Dispersions

“…A video recording system was hooked up to the light microscope for monitoring the morphology changes with time. Double-chained lipids reveal saturation coverage of 1.0 molecule/0.5nm 2 in aqueous media, which are magnitudes different from Lipid Adiphosphate where ordering of Lipid A-diphosphate occurs at concentrations that are less than 1.33 x 10 -11 mbar·s or saturation monolayer coverage of  10 -5 L [58,59]. The surface density of the dye is  10 -2 molecule/nm 2 .…”

Phase Transformations in Lipid A–Diphosphate Initiated by Sodium Hydroxide

“…This was previously observed for systems containing small to large spheres, large rods, or rods in the presence of spheres. , However, there is considerable interest in understanding the physical properties of lipid A–diphosphate dispersions during the titration process with bases, such as NaOH. Lipid A–diphosphate, the endotoxic principle of lipopolysaccharides (LPS) of Gram-negative bacteria, is the major component of the outer leaflet of the outer membrane, and its release in the course of bacterial infections is the cause of septic shock. − Therefore, the phase behavior of lipid A–diphosphate , is important for a variety of reasons which include production, stabilization, and detection of vaccines, − surface phenomena of membrane deformation, , biomineralization, and multivalent anion binding. , …”

“…Lipid A− diphosphate, the endotoxic principle of lipopolysaccharides (LPS) of Gram-negative bacteria, is the major component of the outer leaflet of the outer membrane, and its release in the course of bacterial infections is the cause of septic shock. 39−41 Therefore, the phase behavior of lipid A−diphosphate 42,43 is important for a variety of reasons which include production, stabilization, and detection of vaccines, 44−47 surface phenomena of membrane deformation, 48,49 biomineralization, 50 and multivalent anion binding. 51,52 The present contribution goes beyond previous studies on the crystallization of noncovalently linked polymers, e.g., lipid A−diphosphate or lipid A−monophosphate.…”