Calcium hydroxyapatite can be a significant component of black pigment gallstones. Diverse molecules that bind calcium phosphate inhibit hydroxyapatite precipitation. Because glycine-conjugated bile acids, but not their taurine counterparts, bind calcium phosphate, we studied whether glycochenodeoxycholic acid inhibits calcium hydroxyapatite formation. Glycochenodeoxycholic acid (2 mM) totally ...

Although the polymorphism of calcium carbonate is well known, and its polymorphs--calcite, aragonite, and vaterite--have been highly studied in the context of biomineralization, polyamorphism is a much more recently discovered phenomenon, and the existence of more than one amorphous phase of calcium carbonate in biominerals has only very recently been understood. Here we summarize what is known...

An animal's hard tissue is mainly composed of crystalline calcium phosphate. In vitro, small changes in the reaction conditions affect the species of calcium phosphate formed, whereas, in vivo, distinct types of crystalline calcium phosphate are formed in a well-controlled spatiotemporal-dependent manner. A variety of proteins are involved in hard-tissue formation; however, the mechanisms by wh...

A simple synthetic method is presented for the precipitation of high purity, dry amorphous calcium carbonate (ACC) based on freeze-drying saturated, counter ion free CaCO3 solutions, where the ACC produced shows an extended atmospheric stability. Translation of the methodology to amorphous calcium phosphate demonstrates the generality of the approach.

We introduce giant liposomes to investigate phase transformations in picoliter volumes. Precipitation of calcium carbonate in the confinement of DPPC liposomes leads to dramatic stabilization of amorphous calcium carbonate (ACC). In contrast, amorphous strontium carbonate (ASC) is a transient species, and BaCO3 precipitation leads directly to the formation of crystalline witherite.

objectives: this study aimed to assess the effect of applying casein phosphopeptide–amorphous calcium phosphate (cpp-acp) paste, casein phosphopeptide–amorphous calcium phosphate fluoride (cpp-acpf) paste and sodium fluoride gel on surface microhardness of enamel after microabrasion. materials and methods: thirty freshly extracted human premolars were selected. all samples were subjected to har...

EXAFS can be used to characterise the phase of an amorphous calcified deposit mixed with a crystalline phase which does not contain calcium. In such a mixture, the amorphous phase may not be detectable by X-ray diffraction. This application of EXAFS is illustrated by the characterisation of the calcium phosphate deposited in association with struvite in encrusted urinary catheters.

The hybrid nanoparticles of amorphous calcium phosphate (ACP)-catalase (CAT) developed by in situ biomineralization can create a stable semi-aqueous nanoscale environment for entrapped proteins against thermal denaturation. This finding indicates the importance of an amorphous mineral phase in the preservation of organic macromolecules.

Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60°C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until aft...

Human dental enamel, the hardest tissue in the body, plays a vital role in protecting teeth from wear as a result of daily grinding and chewing as well as from chemical attack. It is well established that the mechanical strength and fatigue resistance of dental enamel are derived from its hierarchical structure, which consists of periodically arranged bundles of hydroxyapatite (HAP) nanowires. ...