Microelectrophoretic studies of gelatin and acacia for the prediction of complex coacervation

Burgess, Diane J.; Carless, J. E.

doi:10.1016/0021-9797(84)90472-7

Cited by 135 publications

(93 citation statements)

References 12 publications

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“…5,6 A number of studies have reported on the complexes formed between polyelectrolytes and proteins under different conditions of pH and salt concentration. [7][8][9] The turbidimetric measurements primarily employed in previous studies [10][11][12] could easily monitor the formation of a complex coacervate or an amorphous precipitate. The formation of ''seemingly'' soluble complexes has also been observed under specific pH and salt concentration conditions in several systems consisting of proteins and polyelectrolytes 9 ; however, the main focus of these studies were on the formation of coacervates.…”

Section: Introductionmentioning

confidence: 99%

Formation of stable nanoparticles via electrostatic complexation between sodium caseinate and gum arabic

2006

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The formation of electrostatic complexes between sodium caseinate and gum arabic (GA) was studied as a function of pH (2.0-7.0), using slow acidification in situ with glucono-delta-lactone (GDL) or titration with HCl. The colloidal behavior of the complexes under specific conditions was investigated using absorbance measurements (at 515 or 810 nm) and dynamic light scattering (DLS). In contrast to the sudden increase in absorbance and subsequent precipitation of sodium caseinate solutions at pH < 5.4, the absorbance values of mixtures of sodium caseinate and GA increased to a level that was dependent on GA concentration at pH 5.4 (pH(c)). The absorbance values remained constant with further decreases in pH until a sudden increase in absorbance was observed (at pH(phi)). The pH(phi) was also dependent upon the GA concentration. Dynamic light scattering (DLS) data showed that the sizes of the particles formed by the complexation of sodium caseinate and GA between pH(c) and pH(phi) were between 100 and 150 nm and these nanoparticles were visualized using negative staining transmission electron microscopy (TEM). Below pH(phi), the nanoparticles associated to form larger particles, causing phase separation. zeta-Potential measurements of the nanoparticles and chemical analysis after phase separation showed that phase separation was a consequence of charge neutralization. The formation of complexes between sodium caseinate and GA was inhibited at high ionic strength (>50 mM NaCl). It is postulated that the structure of the nanoparticles comprises an aggregated caseinate core, protected from further aggregation by steric repulsion of one, or more, electrostatically attached GA molecules.

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Section: Introductionmentioning

confidence: 99%

Formation of stable nanoparticles via electrostatic complexation between sodium caseinate and gum arabic

2006

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“…Protein-polyelectrolyte (PE) coacervates [1][2][3][4][5] are dense, macromolecule-rich liquid phases formed by liquid-liquid phase separation from mixtures of the two macroions. Polyelectrolyte complex coacervation, in general, is thought to be driven by electrostatic attractive forces and by the entropy gain coming from the release of small ions.…”

Section: Introductionmentioning

confidence: 99%

Mesophase separation and probe dynamics in protein–polyelectrolyte coacervates

et al. 2007

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Protein-polyelectrolyte coacervates are self-assembling macroscopically monophasic biomacromolecular fluids whose unique properties arise from transient heterogeneities. The structures of coacervates formed at different conditions of pH and ionic strength from poly(dimethyldiallylammonium chloride) and bovine serum albumin (BSA), were probed using fluorescence recovery after photobleaching. Measurements of self-diffusion in coacervates were carried out using fluorescein-tagged BSA, and similarly tagged Ficoll, a non-interacting branched polysaccharide with the same size as BSA. The results are best explained by temporal and spatial heterogeneities, also inferred from static light scattering and cryo-TEM, which indicate heterogeneous scattering centers of several hundred nm. Taken together with previous dynamic light scattering and rheology studies, the results are consistent with the presence of extensive dilute domains in which are embedded partially interconnected 50-700 nm dense domains. At short length scales, protein mobility is unobstructed by these clusters. At intermediate length scales, proteins are slowed down due to tortuosity effects within the blind alleys of the dense domains, and to adsorption at dense/dilute domain interfaces. Finally, at long length scales, obstructed diffusion is alleviated by the break-up of dense domains. These findings are discussed in terms of previously suggested models for protein-polyelectrolyte coacervates. Possible explanations for the origin of mesophase separation are offered.

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“…1B). We attribute this to electrostatic repulsion between the GA-dispersed SWNTs and the SDS-dispersed latex: GA is a weak polyelectrolyte; it carries carboxylic acid groups and is thus negatively charged above pH 2, [23] above which our measurements are performed. SDS is also negatively charged, which results in electrostatic repulsion.…”

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confidence: 99%

Preparation of Conductive Nanotube–Polymer Composites Using Latex Technology

et al. 2004

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Composites consisting of individual, or bundles of single‐walled, exfoliated nanotubes in a highly viscous polymer matrix (see Figure) are described. The nanotubes and polymer are made compatible using surfactant molecules, hence avoiding the need for direct attraction between the nanotubes and the matrix. The resulting nanotube–polymer composites have a conductivity percolation threshold of 0.28 wt.‐% nanotubes.

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Microelectrophoretic studies of gelatin and acacia for the prediction of complex coacervation

Cited by 135 publications

References 12 publications

Formation of stable nanoparticles via electrostatic complexation between sodium caseinate and gum arabic

Formation of stable nanoparticles via electrostatic complexation between sodium caseinate and gum arabic

Mesophase separation and probe dynamics in protein–polyelectrolyte coacervates

Preparation of Conductive Nanotube–Polymer Composites Using Latex Technology

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