Precipitation in Gels under Conditions of Double Diffusion: Critical Concentrations and Solubility Products of Salts

Srzić, Dunja; Pokrić, Biserka; Pučar, Z.

doi:10.1524/zpch.1976.103.1-4.157

Cited by 11 publications

(8 citation statements)

References 15 publications

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“…The turbid zone and the membranes were formed in all experiments with the precipitating systems CaC12-phosphate buffer, described in the present paper, but had not been observed in experiments with other inorganic precipitating systems [4].…”

Section: Resultsmentioning

confidence: 45%

“…Since the critical precipitating concentrations are equimolar, and the "equivalency rule" demands equivalency at the onset of precipitation under conditions of diffusion [3,4,30,31 ], we may conclude that CaHPO4 is the first-formed precipitate at least in the phase of nucleation. This result does not imply that all phosphate in the buffer (pH 7.4) should be in HPO4"-ionic form; it indicates only that one calcium ion interacts with one phosphate ion during phase of nucleation.…”

Section: Precipitation Discsmentioning

confidence: 99%

“…A simpler description of the procedure was given in a paper dealing with precipitations of slightly soluble salts in agar gel [4].…”

Section: Experimental Procedures Introdudionmentioning

confidence: 99%

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Precipitation of calcium phosphates under conditions of double diffusion in collagen and gels of gelatin and agar

Pokrić

Pučar

1979

Calcif Tissue Int

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One-dimensional double diffusion was applied to determine critical concentrations at which the precipitation of calcium phosphates occurs in reconstituted connective tissue collagen and agar gels at 37 degrees C and in gelatin gels at 25 degrees C. Experiments were performed in the presence of unbuffered 0.15 mol dm-3 NaCl, or 0.15 mol dm-3 NaCl-veronal adjusted to pH 7.4. It was found that critical concentrations of precipitation of both precipitating components, CaCl2 and phosphate buffer (pH 7.4), were equimolar and independent of the ratios of initial concentrations of the components. Critical concentrations of precipitation were not affected by the concentrations and kinds of gels used. The first-formed precipitates showed amorphous structure by X-ray diffraction analyses. Infrared (IR) spectra of the precipitates indicated CaHPO4 . H2O to be their predominant species. The molar Ca/P ratio obtained by chemical analyses was 1.08. This precipitate transformed in time into octacalcium phosphate. In all experiments, two very thin membranes of precipitate were formed in the gel column at the onset of precipitation simultaneously on both sides of the actual disc of precipitate. IR spectra and chemical analyses showed that both membranes were identical to the actual precipitation discs.

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Section: Resultsmentioning

confidence: 45%

Section: Precipitation Discsmentioning

confidence: 99%

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Precipitation of calcium phosphates under conditions of double diffusion in collagen and gels of gelatin and agar

Pokrić

Pučar

1979

Calcif Tissue Int

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“…In a hydrogel, the supersaturation threshold is reduced to a two component reaction of A + B = C where the supersaturation is the ion product [A]×[B], and the reaction is reduced to 2 nd order, AB mM 2 , regardless of the true order of the reaction. 89 This reduction is reaction order is valid because precipitation under double-diffusion in a hydrogel obeys the equivalency rule rather than the ionic solubility law. 89 The empirical value of this supersaturation threshold is unique to the type of hydrogel used, the phase of the crystal being grown (ratio of ions, etc.…”

Section: Evaluation and Design Strategies For Ddssmentioning

confidence: 99%

Rediscovering hydrogel-based double-diffusion systems for studying biomineralization

2012

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For those seeking to model biomineralization in vitro, hydrogels can serve as excellent models of the extracellular matrix (ECM) microenvironment. A major challenge posed in implementing such systems is the logistics involved, from fundamental engineering to experimental design. For the study of calcium phosphate (e.g., hydroxyapatite) formation, many researchers use hydrogel-based double-diffusion systems (DDSs). The various designs of these DDSs are seemingly as unique as their applications. In this Highlight, we present a survey of four distinct types of double-diffusion systems and evaluate them in the context of fundamental diffusion theory. Based upon this analysis, we present the design and evaluation of an optimized system. The techniques and framework for the evaluation and construction of a DDS presented here can be applied to any DDS that a researcher may want to implement for their particular studies of biomineralization.

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“…Precipitation occurred from super-saturated gels with equal equivalents of cations and anions. These critical concentrations were determined for a variety of precipitation systems [42]. Critical concentrations exceeded solubility products reported previously in the literature for most systems, including calcium phosphate precipitates.…”

Section: Double Diffusion and The Calcium To Phosphate Ratiomentioning

confidence: 87%

Diffusion Systems for Evaluation of Biomineralization

Silverman

Boskey

2004

Calcif Tissue Int

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A variety of in vitro study methods have been used to elucidate the roles of matrix molecules in biomineralization processes. Among these, gel diffusion-precipitation studies have proved to be an effective tool. This methodology is uniquely capable of characterizing the effects of matrix molecules on mineralization while only using very small quantities of material. Furthermore, gel methods have been extended for use as a mineralization assay system to characterize modified matrix molecules and synthetic analogues. Here we discuss the advantages and limitations of gelatin, agar, agarose, and other systems for studying the mechanisms of biomineralization. KeywordsHydroxyapatite; Biomineralization; Gel diffusion; Gelatin; Agarose; Agar In Vitro StudiesThe functions of vertebrate and non-vertebrate mineralized tissue matrix biomolecules, such as osteopontin [1][2][3][4], osteonectin [5,6], amelogenin [7,8], bone sialoprotein [2,3,6,9], and a variety of shell proteins [10,11] generally have been demonstrated in a three-step process. First, molecules that may influence the biomineralization process are either isolated from mineralized tissue, purified, and characterized, or cloned and expressed in recombinant forms. Their spatial and temporal distribution in mineralizing tissue, and their presence or absence from diseased or non-mineralizing tissue, as assessed by immunolocalization or in situ hybridization, suggests their role in mineral formation. Second, the molecule being studied can be associated with the biomineralization process in vivo via tissue studies on genetically modified or diseased organisms where expression of the substance of interest is altered, prevented, or enhanced. Third, in vitro mineralization studies may be used to provide insight into the mechanism of action of matrix proteins and to elucidate a molecule's function in vivo [12]. While many different techniques have been used in the in vitro studies, gel precipitation methods, used for over a century for the growth of large crystals [13], have recently been introduced to help elucidate how non-collagenous proteins and other biomolecules act to control biomineralization processes.The interplay of in vivo and in vitro studies allows characterization of a molecule's role in complex living tissue, where we have limited experimental control, against a backdrop of information from well-controlled, simpler precipitation studies. The cell-free in vitro studies allow characterization of an individual compound or mixture's effects on nucleation, growth kinetics, inhibition, and crystal composition and habit, as well as quantitative comparisons We review here the recent application of crystal formation in gels to probe mineralization mechanisms with emphasis placed on hydroxyapatite formation and growth, although the techniques described are applicable to other types of biomineralization.Most in vitro studies of matrix proteins involved in hydroxyapatite (HA) formation have been done in solution, as opposed to gels. The solution studies charact...

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Precipitation in Gels under Conditions of Double Diffusion: Critical Concentrations and Solubility Products of Salts

Cited by 11 publications

References 15 publications

Precipitation of calcium phosphates under conditions of double diffusion in collagen and gels of gelatin and agar

Precipitation of calcium phosphates under conditions of double diffusion in collagen and gels of gelatin and agar

Rediscovering hydrogel-based double-diffusion systems for studying biomineralization

Diffusion Systems for Evaluation of Biomineralization

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