Solubility product of OH-carbonated hydroxyapatite

Ito, Atsuo; Maekawa, Kentaro; Tsutsumi, Sadao; Ikazaki, Fumikazu; Tateishi, Tetsuya

doi:10.1002/(sici)1097-4636(19970915)36:4<522::aid-jbm10>3.0.co;2-c

Cited by 97 publications

(73 citation statements)

References 32 publications

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“…The K IAP value could be estimated 60), 69) from the phosphate concentration, the calcium concentration, pH, the values of constants, and activity coefficients calculated using the DebyeHuckel limiting law, where all of these values are listed in the past reports. 70),71) Figure 8 shows the negative logarithm of the ion activity product (pK IAP ) for HA as a function of the pH value. The pK IAP value decreased linearly with an increase in pH value.…”

Section: )68)supporting

confidence: 71%

“…The pK IAP value decreased linearly with an increase in pH value. The pK IAP and the negative logarithm of the solubility product (pK sp = 118.65) for HA reported previously 70) derived from the physiological solution being saturated for HA at about pH 5.1. The solution is not saturated for HA at a pH value under 5.1, so HA is dissolved in the solution with pH under 5.1.…”

Section: )68)mentioning

confidence: 95%

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Tailored bioceramics of calcium phosphates for regenerative medicine

Ioku

2010

J. Ceram. Soc. Japan

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Calcium phosphate bioceramics, especially those in hydroxyapatite (HA) and ¢-tricalcium phosphate (¢-TCP), are leading candidates for scaffolds used in regenerative medicine for bone tissue. The precise control of chemical composition, pore structure, and crystal faces is important for both the tissue regeneration and bioresorption of the materials. The excellent characteristics of HA and ¢-TCP for cell activity could be shown by using transparent ceramics of HA and ¢-TCP. Both calcium phosphates prepared through hydrothermal processing composed of rod-shaped particles were compared to conventional materials prepared by sintering methods, and their superior properties for bone regeneration were demonstrated. The in vivo behavior of HA and ¢-TCP is discussed from the viewpoint of chemical dissolubility.

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Section: )68)supporting

confidence: 71%

Section: )68)mentioning

confidence: 95%

Tailored bioceramics of calcium phosphates for regenerative medicine

Ioku

2010

J. Ceram. Soc. Japan

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“…The weak absorbance bands at 871cm -1 and the very week bands at 1430 and 1455 cm -1 signify the presence of carbonate [11,12]. No band was detected at 864 cm -1 which if present would indicate the substitution of carbonates for the hydroxyl groups [13]. The broad band from 3700 to 2800 cm -1 and the weak band at 1645 cm -1 can be ascribed to structural water in the molecular form [5].…”

Section: Structure Of the Depositsmentioning

confidence: 98%

Study on the structure and composition of aortic valve calcific deposits. etiological aspects

Prieto¹,

Gomila²,

Söhnel³

et al. 2011

JBPC

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The structures and chemical compositions of valve calcific deposits were investigated. The deposits was chosen arbitrarily and subjected to chemical analysis, observation with scanning microscope, semi-quantitative determination of Ca, Mg, Na, K, P and C elements by energy dispersive X-ray, X-ray diffraction and Fourier transform infra-red spectroscopy carried out. These deposits were found to have non-uniform internal structures composed of layers of a structureless aspidinic inorganic material, substantial amounts of voluminous organic material and in a few samples small spheres were also present. Two groups of deposits with distinctly different chemical compositions were identified: one group with a low Ca/P molar ratio (1.59) and the other group with a high (1.82) Ca/P molar ratio. The deposits belonging to the group with a low Ca/P molar ratio contain higher concentration of magnesium and consist of increased amount of amorphous calcium phosphate. The deposits with a high Ca/P molar ratio contain low concentration of magnesium and consist predominantly of carbonated hydroxyapatite. The inorganic material was identified as a poorly crystalline carbonate hydroxyapatite containing molecular water of the average formula Ca 9.1 Mg 0.4 (Na,K)(PO 4 ) 5.8 (CO 3 ) 0.3 (OH) 2 . The actual chemical composition of the apatitic solid phase varies not only from deposit to deposit but also within the same deposit. The non-uniform internal structure of the deposits, the occasional presence of spherical particles and the variable point composition of the individual deposits indicate that their formation did not proceed under more or less constant conditions.

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“…The percentages of total phosphorus at the given pH, calculated from the dissociation constants of phosphoric acid [13] and reported as 4 ions, were 31% and 4.6% in groups I and II calculi, respectively. Using the procedure described previously [14], we calculated that the supersaturation of urine with respect to carbonate hydroxyapatite was 6.0 for group I (the solubility product of hydroxyapatite containing 2.2 wt% carbonate was 1.17 × 10 −57 mol 9 /L 9 [15]) and 23.6 for group II (the solubility product of stoichiometric hydroxyapatite was 2.03 × 10 −59 mol 9 /L 9 [13]). We did not correct supersaturation for particle size because it changes the absolute values by the same numerical factor for the same particle size and has no effect on the supersaturation ratio, i.e.…”

Section: Thermal Analysismentioning

confidence: 99%

Structure and Composition of Non-Infectious Phosphate Calculi Formed in Patients with Low and High Urinary Phosphate Concentrations

Gráses¹,

Söhnel²,

Gomila³

2013

OJU

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Objective: The aim of this paper was to assess the relationships among chemical, phase and structural composition and etiopathogenic factors of non-infectious phosphate calculi formed in patients with low and high urinary phosphate concentrations, and to characterize the mechanism of their formation related on biochemical results. Material and Methods: Twelve samples of phosphate renal calculi were obtained, 4 from patients with low phosphaturia and 6 from patients with high urinary phosphate concentrations. Their chemical composition was determined qualitatively by energy dispersive X-ray analysis and quantitatively by spectrophotometric and thermal analysis; and their phase composition was determined by Fourier transform infrared transmission spectroscopy and X-ray diffraction. The structure of the calculi was assessed by scanning electron microscopy. Results: Non-infectious phosphate renal calculi of patients with low phosphaturia consist of poorly crystalline carbonate hydroxyapatite, whereas those of patients with high urinary phosphate concentrations consist of poorly crystalline hydroxyapatite with some amount of calcium oxalate crystals. Calculi of patients with high urinary phosphate concentrations are formed at urinary supersaturation with respect to hydroxyapatite and calcium oxalate about 4 times higher than in patients with low phosphaturia. Conclusion: In patients with low phosphaturia, the non-infectious phosphate renal calculi are formed in urine near pH 7 and contain only poorly crystalline carbonate hydroxyapatite. In patients with high urinary phosphate concentrations and hypercalciuria, the calculi are formed in urine near pH 6 and consist of both poorly crystalline hydroxyapatite and some amount of calcium oxalate crystals.

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Solubility product of OH-carbonated hydroxyapatite

Cited by 97 publications

References 32 publications

Tailored bioceramics of calcium phosphates for regenerative medicine

Tailored bioceramics of calcium phosphates for regenerative medicine

Study on the structure and composition of aortic valve calcific deposits. etiological aspects

Structure and Composition of Non-Infectious Phosphate Calculi Formed in Patients with Low and High Urinary Phosphate Concentrations

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