Crystallization of calcium and magnesium phosphates from solutions of low concentration

Abbona, F.; Franchini-Angela, M.

doi:10.1016/0022-0248(90)90009-a

Cited by 65 publications

(30 citation statements)

References 19 publications

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“…From the data in Table 2, the lowest AP CaP at which crystals were observed was in samples with an initial pH of 5.80, whereas the corresponding values were much higher in samples with an initial pH of 7.28. It has previously been shown that brushite can precipitate in poorly supersaturated solutions with a low pH, while other crystal phases of CaP form in solutions with higher a pH level and a higher CaP supersaturation (Abbona and Franchini-Angela, 1990;Lundager-Madsen and Christensson, 1991). A direct comparison between the crystallization in solutions with different pH is hampered by the fact that different crystal phases probably are precipitated, but it is reasonable to assume that other crystals phases than brushite would predominate in solutions with an initial pH of 6.45 and 7.28, as suggested by the scanning electron microscopy in our experiments.…”

Section: Discussionmentioning

confidence: 99%

“…Since it is reasonable to assume that the first step in the crystallization process leading to pure CaP and mixed CaOx/CaP stones starts in the loop of Henle (Coe and Parks, 1990;Kok, 1995;Asplin et al, 1996) or in the distal tubule (Lupták et al, 1994;Tiselius et al, 1999), we found it worthwhile to study the effects of pH on the crystallization of calcium salts in solutions with a composition corresponding to that in the distal tubule.…”

Section: Introductionmentioning

confidence: 99%

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The effect of pH changes on the crystallization of calcium salts in solutions with an ion composition corresponding to that in the distal tubule

Højgaard

Fornander

Nilsson

et al. 1999

Urological Research

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The effect of pH changes on the crystallization in solutions with an ion-composition assumed to correspond to that of urine in the distal part of the distal tubule was examined by recording the number and volume of crystals with a Coulter Multisizer and by studying the crystal morphology by scanning electron microscopy at different degrees of volume reduction. The experiments were carried out with 100 ml samples at different starting pH without and with 20% of dialyzed urine (dU).The number of crystals increased in response to volume reduction. In solutions without dU, 100 or more crystals with diameters in between 2.4 and 45 µm were observed already at a volume reduction of 40% when the initial pH was 7.28. For solutions with pH of 5.80 and 6.45, the corresponding values were 60% and 80%, respectively. In the presence of dU, an appearance of crystals was recorded at volume reductions of less than 20%. In solutions with an initial pH of 5.80 and 6.45, the crystal number was greater with dU than without; such a difference was not recorded at pH 7.28.In samples containing dU, the mean crystal volume (MCV) varied very little when the sample volume was reduced. The same was found in solutions without dU when the initial pH was 5.80 and 7.28; the MCV was greater in the samples with pH 6.45.Scanning electron microscopy of solutions reduced to 30-40% of the original volume showed that calcium phosphate had formed in solutions with a starting pH of 7.28 and 6.45. In solutions with pH 5.80, calcium oxalate crystals were observed with calcium phosphate.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of pH changes on the crystallization of calcium salts in solutions with an ion composition corresponding to that in the distal tubule

Højgaard

Fornander

Nilsson

et al. 1999

Urological Research

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“…Of interest to biological cements, magnesium can stabilize amorphous calcium phosphate against phase transformation (Termine et al 1970), promote the formation of whitlockite (Mg-substituted tricalcium phosphate; Rowles 1968) and inhibit the transformation of brushite to octacalcium phosphate and HAP (Bigi et al 1988). Previous studies of the effects of magnesium on the growth of brushite have found that magnesium acts as a growth inhibitor but it also stabilizes brushite against dissolution up to neutral pH (Abbona et al 1986;Abbona & Franchini-Angela 1990).…”

Section: (I) the Impact Of Magnesium On Brushite Growthmentioning

confidence: 99%

Molecular mechanisms of crystallization impacting calcium phosphate cements

Giocondi

El-Dasher

Nancollas

et al. 2010

Phil. Trans. R. Soc. A.

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The biomineral calcium hydrogen phosphate dihydrate (CaHPO 4 ·2H 2 O), known as brushite, is a malleable material that both grows and dissolves faster than most other calcium minerals, including other calcium phosphate phases, calcium carbonates and calcium oxalates. Within the body, this ready formation and dissolution can play a role in certain diseases, such as kidney stone and plaque formation. However, these same properties, along with brushite's excellent biocompatibility, can be used to great benefit in making resorbable biomedical cements. To optimize cements, additives are commonly used to control crystallization kinetics and phase transformation. This paper describes the use of in situ scanning probe microscopy to investigate the role of several solution parameters and additives in brushite atomic step motion. Surprisingly, this work demonstrates that the activation barrier for phosphate (rather than calcium) incorporation limits growth kinetics and that additives such as magnesium, citrate and bisphosphonates each influence step motion in distinctly different ways. Our findings provide details of how, and where, molecules inhibit or accelerate kinetics. These insights have the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives.

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“…Brushite may form at pH>6 when Mg/Ca ratio is about 4, concentration which supposedly inhibits hydroxylapatite precipitation. According to Abbona and Franchini-Angela's (1990) experiments, the brushite-hydroxylapatite association forms from initial solutions with low concentration of Ca and P (0.005 M) and initial pH values between 5.5 and 8. This process involves the decrease of pH and starts with the precipitation of unstable mineral phases, which subsequently evolve to more such as taranakite and variscite, which are stable under acidic environmental conditions, or not so common phosphates such as leucophosphite (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…stable phases. The first to form are brushite and an amorphous calcium phosphate, followed by the conversion of the latter to hydroxylapatite (if Mg/Ca < 0.4) or to whitlockite (if Mg/Ca > 0.4) (Abbona and Franchini-Angela, 1990). Whitlockite was not found in samples from Zidită Cave and we assume that Mg/Ca ratio in the solutions, which interacted with the organic material was low or 0.…”

Section: Resultsmentioning

confidence: 99%