fbpx
Wikipedia

Amorphous calcium phosphate

January 01, 1970

Amorphous calcium phosphate (ACP) is a glassy solid that is formed from the chemical decomposition of a mixture of dissolved phosphate and calcium salts (e.g. (NH4)2HPO4 + Ca(NO3)2). The resulting amorphous mixture consists mostly of calcium and phosphate, but also contains varying amounts of water and hydrogen and hydroxide ions, depending on the synthesis conditions.[1] Such mixtures are also known as calcium phosphate cement.[2]

ACP is generally categorized into either "amorphous tricalcium phosphate" (ATCP) or calcium-deficient hydroxyapatite (CDHA). CDHA is sometimes termed "apatitic calcium triphosphate."[1][3][4] The composition of amorphous calcium phosphate is CaxHy(PO4)z·nH2O, where n is between 3 and 4.5. CDHA has a general formula of Ca9(HPO4)(PO4)5(OH).[4] Precipitation from a moderately supersaturated and basic solution of a magnesium salt produces amorphous magnesium calcium phosphate (AMCP), in which magnesium incorporated into the ACP structure.[5]

A commercial preparation of ACP is casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), derived from cow milk. It is sold under various brand names including Recaldent and Tooth Mousse, intended to be applied directly to teeth. Its clinical usefulness is unproven.[6]

Biogenic ACP edit

Biogenic ACP has been found in the inner ear of embryonic sharks, mammalian milk and dental enamel. However, whilst its unequivocal presence in bones and teeth is debated, there is evidence that transient amorphous precursors are involved in the development of bone and teeth.[4] The ACP in bovine milk (CPP-ACP) is believed to involve calcium phosphate nanoclusters in a shell of casein phosphopeptides. A typical casein micelle of radius 100 nm contains around 10,000 casein molecules and 800 nanoclusters of ACP, each about 4.8 nm in diameter. The concentration of calcium phosphate is higher in milk than in serum, but it rarely forms deposits of insoluble phosphates.[7] Unfolded phosphopeptides are believed to sequester ACP nanoclusters[8] and form stable complexes in other biofluids such as urine and blood serum, preventing deposition of insoluble calcium phosphates and calcification of soft tissue. In the laboratory, stored samples of formulations of artificial blood, serum, urine and milk (which approximate the pH of the naturally occurring fluid) deposit insoluble phosphates. The addition of suitable phosphopeptides prevents precipitation.[7]

Posner's clusters edit

Following investigations into the composition of amorphous calcium phosphates precipitated under different conditions, Posner and Betts suggested in the mid-1970s that the structural unit of ACP was a neutral cluster Ca9(PO4)6.[4] Calculations support the description of a cluster with central Ca2+ ion surrounded by six phosphate PO43− anions, which in turn are surrounded by eight further calcium ions.[9] The resulting cluster is estimated to have a diameter of around 950 pm (0.95 nm). These are now generally referred to as Posner's clusters. Precipitated ACP is believed to be made up of particles containing a number of Posner's clusters with water in the intervening spaces. While plasma spray coated ACP may contain Posner's clusters, there cannot be any water present.[4] New studies propose the idea of posner clusters acting as neural qbits because their entangled 31P have a long relaxation time and are in a S6 symmetry. The idea behind it is that the posner molecules meld and release calcium-ions which stimulises the neurons.[10]

Use in dental treatment edit

Amorphous calcium phosphate in combination with casein phosphopeptide has been used as a dental treatment to treat incipient dental decay. ACP sees its main use as an occluding agent, which aids in reducing sensitivity. Studies have shown that it does form a remineralized phase of hydroxyapatite consistent with the natural enamel.[citation needed] In addition, clinical studies have shown that patients who whiten their teeth have reduced sensitivity after treatment.[11] It is believed that ACP hydrolyzes under physiological temperatures and pH to form octacalcium phosphate as an intermediate, and then surface apatite.[citation needed]

Method of mineralization edit

ACP lacks the long-range, periodic atomic-scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at  , and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystallites. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo.[12]

Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures.[12]

See also edit

References edit

  1. ^ a b Destainville, A.; Champion, E.; Bernache-Assollant, D.; Laborde, E. (April 2003). "Synthesis, characterization and thermal behavior of apatitic tricalcium phosphate". Materials Chemistry and Physics. 80 (1): 269–277. doi:10.1016/S0254-0584(02)00466-2.
  2. ^ Al-Sanabani, JS; Madfa, AA; Al-Sanabani, FA (2013). "Application of calcium phosphate materials in dentistry". International Journal of Biomaterials. 2013: 876132. doi:10.1155/2013/876132. PMC 3710628. PMID 23878541.
  3. ^ Rey, C.; Combes, C.; Drouet, C.; Grossin, D. (2011). "Bioactive Ceramics: Physical Chemistry". Comprehensive Biomaterials. pp. 187–221. doi:10.1016/B978-0-08-055294-1.00178-1. ISBN 978-0-08-055294-1.
  4. ^ a b c d e Dorozhkin, Sergey V. (December 2010). "Amorphous calcium (ortho)phosphates". Acta Biomaterialia. 6 (12): 4457–4475. doi:10.1016/j.actbio.2010.06.031. PMID 20609395.
  5. ^ Babaie, Elham; Zhou, Huan; Lin, Boren; Bhaduri, Sarit B. (August 2015). "Influence of ethanol content in the precipitation medium on the composition, structure and reactivity of magnesium–calcium phosphate". Materials Science and Engineering: C. 53: 204–211. doi:10.1016/j.msec.2015.04.011. PMID 26042708.
  6. ^ Hani, Thikrayat Bani; O'Connell, Anne C.; Duane, Brett (24 June 2016). "Casein phosphopeptide-amorphous calcium phosphate products in caries prevention". Evidence-Based Dentistry. 17 (2): 46–47. doi:10.1038/sj.ebd.6401168. PMID 27339237.
  7. ^ a b Holt, Carl (June 2013). "Unfolded phosphopolypeptides enable soft and hard tissues to coexist in the same organism with relative ease". Current Opinion in Structural Biology. 23 (3): 420–425. doi:10.1016/j.sbi.2013.02.010. PMID 23622834.
  8. ^ Holt, Carl; Sørensen, Esben S.; Clegg, Roger A. (2009). "Role of calcium phosphate nanoclusters in the control of calcification". FEBS Journal. 276 (8): 2308–2323. doi:10.1111/j.1742-4658.2009.06958.x. ISSN 1742-464X. PMID 19292864.
  9. ^ Kanzaki, Noriko; Treboux, Gabin; Onuma, Kazuo; Tsutsumi, Sadao; Ito, Atsuo (November 2001). "Calcium phosphate clusters". Biomaterials. 22 (21): 2921–2929. doi:10.1016/s0142-9612(01)00039-4. PMID 11561898.
  10. ^ Swift, Michael; Fischer, Mathew; van de Walle, Chris (2018). "Posner molecules: From atomic structure to nuclear spins". Nature. 20 (18): 12373–12380. arXiv:1711.05899. Bibcode:2018PCCP...2012373S. doi:10.1039/C7CP07720C. PMID 29379925. S2CID 3212404.
  11. ^ Van Haywood, B (2002). "Dentine hypersensitivity: bleaching and restorative considerations for successful management". International Dental Journal. 52 (5): 376–384. doi:10.1002/j.1875-595x.2002.tb00937.x. S2CID 72558772.
  12. ^ a b Zhao, Jie; Liu, Yu; Sun, Wei-bin; Zhang, Hai (December 2011). "Amorphous calcium phosphate and its application in dentistry". Chemistry Central Journal. 5 (1): 40. doi:10.1186/1752-153X-5-40. PMC 3143077. PMID 21740535.

External links edit

  • Mahamid, J.; Aichmayer, B.; Shimoni, E.; Ziblat, R.; Li, C.; Siegel, S.; Paris, O.; Fratzl, P.; Weiner, S.; Addadi, L. (2010). "Mapping amorphous calcium phosphate transformation into crystalline mineral from the cell to the bone in zebrafish fin rays". Proc. Natl. Acad. Sci. U.S.A. 107 (14): 6316–21. Bibcode:2010PNAS..107.6316M. doi:10.1073/pnas.0914218107. PMC 2851957. PMID 20308589.
  • Zhao, J.; Liu, Y.; Sun, W. B.; Zhang, H. (2011). "Amorphous calcium phosphate and its application in dentistry". Chem. Cent. J. 5: 40. doi:10.1186/1752-153X-5-40. PMC 3143077. PMID 21740535.
  • Ming S. Tung. (PDF). American Dental Association. Archived from the original (PDF) on 2013-01-25.

January 01, 1970
amorphous, calcium, phosphate, this, article, technical, most, readers, understand, please, help, improve, make, understandable, experts, without, removing, technical, details, july, 2017, learn, when, remove, this, message, glassy, solid, that, formed, from, . This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details July 2017 Learn how and when to remove this message Amorphous calcium phosphate ACP is a glassy solid that is formed from the chemical decomposition of a mixture of dissolved phosphate and calcium salts e g NH4 2HPO4 Ca NO3 2 The resulting amorphous mixture consists mostly of calcium and phosphate but also contains varying amounts of water and hydrogen and hydroxide ions depending on the synthesis conditions 1 Such mixtures are also known as calcium phosphate cement 2 ACP is generally categorized into either amorphous tricalcium phosphate ATCP or calcium deficient hydroxyapatite CDHA CDHA is sometimes termed apatitic calcium triphosphate 1 3 4 The composition of amorphous calcium phosphate is CaxHy PO4 z nH2O where n is between 3 and 4 5 CDHA has a general formula of Ca9 HPO4 PO4 5 OH 4 Precipitation from a moderately supersaturated and basic solution of a magnesium salt produces amorphous magnesium calcium phosphate AMCP in which magnesium incorporated into the ACP structure 5 A commercial preparation of ACP is casein phosphopeptide amorphous calcium phosphate CPP ACP derived from cow milk It is sold under various brand names including Recaldent and Tooth Mousse intended to be applied directly to teeth Its clinical usefulness is unproven 6 Contents 1 Biogenic ACP 2 Posner s clusters 3 Use in dental treatment 4 Method of mineralization 5 See also 6 References 7 External linksBiogenic ACP editBiogenic ACP has been found in the inner ear of embryonic sharks mammalian milk and dental enamel However whilst its unequivocal presence in bones and teeth is debated there is evidence that transient amorphous precursors are involved in the development of bone and teeth 4 The ACP in bovine milk CPP ACP is believed to involve calcium phosphate nanoclusters in a shell of casein phosphopeptides A typical casein micelle of radius 100 nm contains around 10 000 casein molecules and 800 nanoclusters of ACP each about 4 8 nm in diameter The concentration of calcium phosphate is higher in milk than in serum but it rarely forms deposits of insoluble phosphates 7 Unfolded phosphopeptides are believed to sequester ACP nanoclusters 8 and form stable complexes in other biofluids such as urine and blood serum preventing deposition of insoluble calcium phosphates and calcification of soft tissue In the laboratory stored samples of formulations of artificial blood serum urine and milk which approximate the pH of the naturally occurring fluid deposit insoluble phosphates The addition of suitable phosphopeptides prevents precipitation 7 Posner s clusters editFollowing investigations into the composition of amorphous calcium phosphates precipitated under different conditions Posner and Betts suggested in the mid 1970s that the structural unit of ACP was a neutral cluster Ca9 PO4 6 4 Calculations support the description of a cluster with central Ca2 ion surrounded by six phosphate PO43 anions which in turn are surrounded by eight further calcium ions 9 The resulting cluster is estimated to have a diameter of around 950 pm 0 95 nm These are now generally referred to as Posner s clusters Precipitated ACP is believed to be made up of particles containing a number of Posner s clusters with water in the intervening spaces While plasma spray coated ACP may contain Posner s clusters there cannot be any water present 4 New studies propose the idea of posner clusters acting as neural qbits because their entangled 31P have a long relaxation time and are in a S6 symmetry The idea behind it is that the posner molecules meld and release calcium ions which stimulises the neurons 10 Use in dental treatment editAmorphous calcium phosphate in combination with casein phosphopeptide has been used as a dental treatment to treat incipient dental decay ACP sees its main use as an occluding agent which aids in reducing sensitivity Studies have shown that it does form a remineralized phase of hydroxyapatite consistent with the natural enamel citation needed In addition clinical studies have shown that patients who whiten their teeth have reduced sensitivity after treatment 11 It is believed that ACP hydrolyzes under physiological temperatures and pH to form octacalcium phosphate as an intermediate and then surface apatite citation needed Method of mineralization editACP lacks the long range periodic atomic scale order of crystalline calcium phosphates The X ray diffraction pattern is broad and diffuse with a maximum at 2 8 25 displaystyle 2 theta 25 circ nbsp and no other different features compared with well crystallized hydroxyapatite Under electron microscopy its morphological form is shown as small spheroidal particles in the scale of tenths nanometer In aqueous media ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystallites It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo 12 Moreover it can increase alkaline phosphatase activities of mesoblasts enhance cell proliferation and promote cell adhesion The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration ACP may also be a potential remineralizing agent in dental applications Recently developed ACP filled bioactive composites are believed to be effective anti demineralizing remineralizing agents for the preservation and repair of tooth structures 12 See also edit nbsp Medicine portal Remineralisation of teethReferences edit a b Destainville A Champion E Bernache Assollant D Laborde E April 2003 Synthesis characterization and thermal behavior of apatitic tricalcium phosphate Materials Chemistry and Physics 80 1 269 277 doi 10 1016 S0254 0584 02 00466 2 Al Sanabani JS Madfa AA Al Sanabani FA 2013 Application of calcium phosphate materials in dentistry International Journal of Biomaterials 2013 876132 doi 10 1155 2013 876132 PMC 3710628 PMID 23878541 Rey C Combes C Drouet C Grossin D 2011 Bioactive Ceramics Physical Chemistry Comprehensive Biomaterials pp 187 221 doi 10 1016 B978 0 08 055294 1 00178 1 ISBN 978 0 08 055294 1 a b c d e Dorozhkin Sergey V December 2010 Amorphous calcium ortho phosphates Acta Biomaterialia 6 12 4457 4475 doi 10 1016 j actbio 2010 06 031 PMID 20609395 Babaie Elham Zhou Huan Lin Boren Bhaduri Sarit B August 2015 Influence of ethanol content in the precipitation medium on the composition structure and reactivity of magnesium calcium phosphate Materials Science and Engineering C 53 204 211 doi 10 1016 j msec 2015 04 011 PMID 26042708 Hani Thikrayat Bani O Connell Anne C Duane Brett 24 June 2016 Casein phosphopeptide amorphous calcium phosphate products in caries prevention Evidence Based Dentistry 17 2 46 47 doi 10 1038 sj ebd 6401168 PMID 27339237 a b Holt Carl June 2013 Unfolded phosphopolypeptides enable soft and hard tissues to coexist in the same organism with relative ease Current Opinion in Structural Biology 23 3 420 425 doi 10 1016 j sbi 2013 02 010 PMID 23622834 Holt Carl Sorensen Esben S Clegg Roger A 2009 Role of calcium phosphate nanoclusters in the control of calcification FEBS Journal 276 8 2308 2323 doi 10 1111 j 1742 4658 2009 06958 x ISSN 1742 464X PMID 19292864 Kanzaki Noriko Treboux Gabin Onuma Kazuo Tsutsumi Sadao Ito Atsuo November 2001 Calcium phosphate clusters Biomaterials 22 21 2921 2929 doi 10 1016 s0142 9612 01 00039 4 PMID 11561898 Swift Michael Fischer Mathew van de Walle Chris 2018 Posner molecules From atomic structure to nuclear spins Nature 20 18 12373 12380 arXiv 1711 05899 Bibcode 2018PCCP 2012373S doi 10 1039 C7CP07720C PMID 29379925 S2CID 3212404 Van Haywood B 2002 Dentine hypersensitivity bleaching and restorative considerations for successful management International Dental Journal 52 5 376 384 doi 10 1002 j 1875 595x 2002 tb00937 x S2CID 72558772 a b Zhao Jie Liu Yu Sun Wei bin Zhang Hai December 2011 Amorphous calcium phosphate and its application in dentistry Chemistry Central Journal 5 1 40 doi 10 1186 1752 153X 5 40 PMC 3143077 PMID 21740535 External links editMahamid J Aichmayer B Shimoni E Ziblat R Li C Siegel S Paris O Fratzl P Weiner S Addadi L 2010 Mapping amorphous calcium phosphate transformation into crystalline mineral from the cell to the bone in zebrafish fin rays Proc Natl Acad Sci U S A 107 14 6316 21 Bibcode 2010PNAS 107 6316M doi 10 1073 pnas 0914218107 PMC 2851957 PMID 20308589 Zhao J Liu Y Sun W B Zhang H 2011 Amorphous calcium phosphate and its application in dentistry Chem Cent J 5 40 doi 10 1186 1752 153X 5 40 PMC 3143077 PMID 21740535 Ming S Tung ACP Technology Amorphous Calcium Phosphate forming Fluoride Varnishes PDF American Dental Association Archived from the original PDF on 2013 01 25 Retrieved from https en wikipedia org w index php title Amorphous calcium phosphate amp oldid 1187824988, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.