Crystallization at Multiple Sites inside Particles of Amorphous Calcium Phosphate

Wang, Chenguang; Liao, Jia-Wang; Gou, Bao-Di; Huang, Jian; Tang, Ruikang; Tao, Jinhui; Zhang, Tian‐Lan; Wang, Kui

doi:10.1021/cg801069t

Cited by 64 publications

(109 citation statements)

References 22 publications

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“…The transformation proceeds via direct conversion of an amorphous structure into crystalline ones. This kinetics is attributed to a common cluster unit present in both the amorphous and crystalline phases [11][12][13][14][15]. Posner's cluster [11] and its symmetric isomers [16] were proposed for this common cluster, and then more complex structures of clusters were found through experimental and computational investigations [17,18].…”

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confidence: 94%

Metastable Intermediate Phase during Phase Transformation of Calcium Phosphates

Onuma¹,

Sugiura²

2015

J Biotechnol Biomater

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Phase transformation of calcium phosphates from amorphous to crystalline phases around neutral pH proceeds via direct structure conversion using non-ionic elementary units. This transformation inevitably forms metastable intermediate-structured phase(s) between the two end phases. In addition to conventional calcium phosphate phases appearing in the transformation, new unknown phases were observed. They did not correspond to simply poor crystalline materials of conventional phases and instead had particular structures. One was pseudo-OCP, which lacked the HPO 4 -OH layers in the conventional OCP structure.Keywords: Phase transformation; Amorphous phase; Intermediate phase; OCP; HAP Calcium phosphates have been energetically investigated for more than half a century because of their important role not only in forming hard tissues such as bone and teeth but also being a frequent cause of calculus and arteriosclerosis [1,2]. One factor hindering a sound understanding of their formation mechanism is that they appear in several forms at room to body temperatures [3,4]. For example, amorphous calcium phosphate (ACP), dicalcium phosphate dihydrate (DCPD), β-tricalcium phosphate (β-TCP), octacalcium phosphate (OCP), and hydroxyapatite (HAP) form in weak acidic to weak basic calcium phosphate solutions. They precipitate and stably exist or transform into other more stable phases depending on the solution conditions. Transformation between each calcium phosphate [5][6][7] is of particular interest because the control of this process results in obtaining a desirable phase that can contribute to the design of calciumphosphate-based biomaterials with novel functions.Two phase-transformation mechanisms have been proposed. One is solvent-mediated transformation, which is the simple dissolution and growth of materials depending on the difference in solubility. A representative example for calcium phosphate is the hydrolysis of DCPD and subsequent growth of OCP [8]. The other is structural conversion from metastable to stable phases as was revealed in situ using a light scattering technique [9,10]. If the concentrations of calcium and phosphate ions in the solution are sufficiently high, ACP first forms in the solution and transforms into other phases such as OCP and HAP. The transformation proceeds via direct conversion of an amorphous structure into crystalline ones. This kinetics is attributed to a common cluster unit present in both the amorphous and crystalline phases [11][12][13][14][15]. Posner's cluster [11] and its symmetric isomers [16] were proposed for this common cluster, and then more complex structures of clusters were found through experimental and computational investigations [17,18]. That the clusters can be decomposed into smaller ion pairs as the minimum unit was also proposed [19], indicating the need for more careful investigation of the elemental unit in the phase transformation of calcium phosphates.Leaving aside the question about the structure of the minimum unit, we note that it is well accepte...

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confidence: 94%

Metastable Intermediate Phase during Phase Transformation of Calcium Phosphates

Onuma¹,

Sugiura²

2015

J Biotechnol Biomater

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“…Under laboratory conditions, some researchers have suggested that Ca PO 4 precursors crystallize prior to hydroxyapatite formation (Feenstra and de Bruyn 1979), while others have found rapid formation (~85 minutes) of hydroxyapatite (Wang et al 2009). However, given the background P concentration in L22A Haggard et al (2001b) and Marti et al (2004) who studied wastewater treatment water discharge into streams and found SRP uptake lengths of 9 to 31 km (5.6 to 19.3 mi) and 0.1 to 14 km (0.06 to 8.7 mi), respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Under laboratory conditions, some researchers have suggested that Ca PO 4 precursors crystallize prior to hydroxyapatite formation (Feenstra and de Bruyn 1979), while others have found rapid formation (~85 minutes) of hydroxyapatite (Wang et al 2009). However, given the background P concentration in L22A , and the thermodynamic data found in PHREEQC, it is unlikely that background water P concentrations were controlled by bottom sediment Ca mineral species because PHREEQC predicted a P concentration of 1.104 × 10 -6 mg L -1 (1.104 × 10 -6 ppm) for the preinjection model.…”

Section: Resultsmentioning

confidence: 99%

Assessment of phosphorus retention in irrigation laterals

Ippolito¹,

Nelson²

2013

Journal of Soil and Water Conservation

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Irrigation laterals transport irrigation return flow, including water, sediment, and dissolved nutrients, such as phosphorus (P), back to surface water bodies. Phosphorus transformations during transport can affect both P bioavailability and the best management practices selected to minimize P inputs to waters of the United States. The objective of this study was to determine P retention in three irrigation laterals. Soluble reactive P (SRP) concentrations in lateral waters were increased from 0.08 to 0.25 mg L -1 (0.08 to 0.25 ppm) by constantly injecting a phosphate (PO 4 ) solution for 2.5 hours. Bromide (Br) was used as a conservative tracer to determine dilution effects. Water was sampled at 10-minute intervals, beginning 30 minutes prior to injection and 120 minutes following injection, at one upstream location and various downstream locations to approximately 1,550 m (~1 mi) from injection sites. When at steady state, SRP concentrations only decreased by 5% over the lengths studied, equating to P uptake lengths of over 18 km (11.2 mi), which was one to two orders of magnitude greater than natural streams; the linear SRP uptake rate was 0.011 mg L -1 km -1 (0.018 ppm mi -1). Longer P uptake lengths and lower uptake rates in irrigation laterals, as compared to natural streams, may be due to the elevated sediment equilibrium P concentration, greater water velocities, and removal of vegetation causing a reduction in frictional resistance. Reducing water velocities should optimize irrigation lateral conditions to reduce uptake length and maximize P uptake. Key words: coulee-irrigation lateral-retention-soluble reactive phosphorus-transportAquatic resources in the United States are among its most valuable assets, yet approximately 40% of assessed stream miles, 45% of assessed lake acres, and 50% of assessed estuary acres are impaired (USEPA 2003). The transport of excess nutrients is one of the leading causes of waterway impairment (USEPA 2003). In particular, soluble reactive phosphorus (SRP) transport in aquatic systems is of interest because phosphorus (P) is commonly regarded as the limiting nutrient governing primary production in fresh water systems (Foy 2005). Specifically, P transport in return-flow irrigation laterals may be a significant P source to river systems such as the Snake River in Idaho. Thus, determining and understanding the uptake distance SRP travels prior to being removed from solution during source-tosink water movement could help identify whether current regional soil and water management strategies are having as significant of an impact on water quality improvement as intended.Soluble reactive P travel distance during water transport can be quantified in terms of P spiraling length, or the distance SRP travels as it cycles through dissolved to particulate (organic or inorganic forms) and back to the dissolved state (Davis and Minshall 1999). Total spiraling length is the sum of uptake length (distance traveled in the dissolved form) and turnover length (distance traveled in...

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“…15 We find that select precursors yield stable amorphous calcium phosphate from electrochemically assisted syntheses, but only in the absence of collagen. Figure 2 shows representative IR spectra that demonstrate collagen's influence on phase selectivity.…”

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confidence: 82%

“…Our experiments do not substantiate a probable mechanism, but recent theoretical and experimental investigations have begun to address aspects of this question. 6,12,14,15,19 In conclusion, electrochemically assisted synthesis, based on isoelectric focusing, offers an expedient way to make robust collagen-calcium phosphate composites with controlled mineral phase.…”

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confidence: 98%

Collagen-Membrane-Induced Calcium Phosphate Electrocrystallization

Kumar¹,

S²,

Poduska³

2010

Crystal Growth & Design

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Electrosynthesized type I collagen membranes provide a robust scaffold for phase-controlled nucleation of carbonated hydroxyapatite, which is similar to the mineral composition of natural bone. Phase selectivity persists under a wide range of electrosynthesis conditions that would, in the absence of the membrane, produce other calcium phosphate phases such as brushite or amorphous calcium phosphate. Results also indicate enhanced mineral formation in the presence of collagen.

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Crystallization at Multiple Sites inside Particles of Amorphous Calcium Phosphate

Cited by 64 publications

References 22 publications

Metastable Intermediate Phase during Phase Transformation of Calcium Phosphates

Metastable Intermediate Phase during Phase Transformation of Calcium Phosphates

Assessment of phosphorus retention in irrigation laterals

Collagen-Membrane-Induced Calcium Phosphate Electrocrystallization

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