Tricalcium phosphate

Tricalcium phosphate
IUPAC name	Tricalcium diphosphate
Other names	Whitlockite
Identifiers
CAS number	7758-87-4 Y
PubChem	516943
Properties
Molecular formula	Ca3O8P2
Molar mass	310.18 g/mol
Appearance	White amorphous powder
Density	3.14 g/cm3
Melting point	Liquifies under high pressure at 1670 K (1391 °C)
Thermochemistry
Std enthalpy of formation ΔfHo298	−982.3 kJ/mol (α-form) −984.9 kJ/mol (β-form)
Hazards
EU Index	Not listed
Flash point	Non-flammable
Related compounds
Other anions	Calcium pyrophosphate
Other cations	Magnesium phosphate Dicalcium phosphate Monocalcium phosphate Strontium phosphate
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tricalcium phosphate is a compound with formula Ca₃(PO₄)₂. It is also known as calcium orthophosphate, tertiary calcium phosphate, tribasic calcium phosphate, or "bone ash" (calcium phosphate being one of the main combustion products of bone).

It has an alpha and a beta crystal form, the alpha state being formed at high temperatures. As rock, it is found in Whitlockite.

General case

In minerals, "calcium phosphate" refers to minerals containing calcium ions (Ca²⁺) together with orthophosphates (PO₄^3-), metaphosphates or pyrophosphates (P₂O₇^4-) and occasionally hydrogen or hydroxide ions.

Especially, the common mineral apatite has formula Ca₅(PO₄)₃X, where X is F, Cl, OH, or a mixture; it is hydroxyapatite if the extra ion is mainly hydroxide. Much of the "tricalcium phosphate" on the market is actually powdered hydroxyapatite.

Natural occurrence

It is found in nature as a rock in Morocco, Israel, Philippines, Egypt, and Kola (Russia) and in smaller quantities in some other countries. The natural form is not completely pure, and there are some other components like sand and lime which can change the composition. In terms of P₂O₅, most calcium phosphate rocks have a content of 30% to 40% P₂O₅ in weight.

The skeletons and teeth of vertebrate animals are composed of calcium phosphate, mainly hydroxylapatite.

Uses

Tricalcium phosphate is used in powdered spices as an anti-caking agent.

Calcium phosphate is an important raw material for the production of phosphoric acid and fertilizers, for example in the Odda process.

Calcium phosphate is also a raising agent (food additives) E341. Is a mineral salt found in rocks and bones, it is used in cheese products.

It is also used as a nutritional supplement^[1] and occurs naturally in cow milk, although the most common and economical forms for supplementation are calcium carbonate (which should be taken with food) and calcium citrate (which can be taken without food).^[2] There is some debate about the different bioavailabilities of the different calcium salts.

It is commonly used in porcelain and dental powders, and medically as an antacid or calcium supplement, although calcium carbonate is more common in this regard.

It can be used as a tissue replacement for repairing bony defects when autogenous bone graft is not feasible or possible.^[3][4][5] It may be used alone or in combination with a biodegradable, resorbable polymer such as polyglycolic acid.^[6] It may also be combined with autologous materials for a bone graft.^[7][8]

Another practical application of the compound is its use in gene transfection. The calcium ions can make a cell competent (a euphemism for "rip holes in its membrane") to allow exogenous genes to enter the cell by diffusion. A heat shock afterwards then invokes the cell to repair itself. This is a quick and easy method for transfection, albeit a rather inefficient one.

References

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1. ^ Bonjour JP, Carrie AL, Ferrari S, Clavien H, Slosman D, Theintz G, Rizzoli R (March 1997). "Calcium-enriched foods and bone mass growth in prepubertal girls: a randomized, double-blind, placebo-controlled trial". J. Clin. Invest. 99 (6): 1287–94. doi:10.1172/JCI119287. PMID 9077538. PMC 507944. http://dx.doi.org/10.1172/JCI119287. Retrieved 2009-10-25. 
2. ^ Straub DA (June 2007). "Calcium supplementation in clinical practice: a review of forms, doses, and indications". Nutr Clin Pract 22 (3): 286–96. PMID 17507729. http://ncp.sagepub.com/cgi/pmidlookup?view=long&pmid=17507729. 
3. ^ Paderni S, Terzi S, Amendola L (September 2009). "Major bone defect treatment with an osteoconductive bone substitute". Musculoskelet Surg 93 (2): 89–96. doi:10.1007/s12306-009-0028-0. PMID 19711008. 
4. ^ Moore DC, Chapman MW, Manske D (1987). "The evaluation of a biphasic calcium phosphate ceramic for use in grafting long-bone diaphyseal defects". Journal of Orthopaedic Research : Official Publication of the Orthopaedic Research Society 5 (3): 356–65. doi:10.1002/jor.1100050307. PMID 3040949. 
5. ^ Lange TA, Zerwekh JE, Peek RD, Mooney V, Harrison BH (1986). "Granular tricalcium phosphate in large cancellous defects". Annals of Clinical and Laboratory Science 16 (6): 467–72. PMID 3541772. 
6. ^ Cao H, Kuboyama N (September 2009). "A biodegradable porous composite scaffold of PGA/beta-TCP for bone tissue engineering". Bone. doi:10.1016/j.bone.2009.09.031. PMID 19800045. 
7. ^ Erbe EM, Marx JG, Clineff TD, Bellincampi LD (October 2001). "Potential of an ultraporous beta-tricalcium phosphate synthetic cancellous bone void filler and bone marrow aspirate composite graft". European Spine Journal : Official Publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society 10 Suppl 2: S141–6. doi:10.1007/s005860100287. PMID 11716011. 
8. ^ Bansal S, Chauhan V, Sharma S, Maheshwari R, Juyal A, Raghuvanshi S (July 2009). "Evaluation of hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute for posterolateral spinal fusion". Indian Journal of Orthopaedics 43 (3): 234–9. doi:10.4103/0019-5413.49387. PMID 19838344.