Rates of transport through a capsule membrane to attain Donnan equilibrium

Sherwood, J. D.; Risso, Frédéric; Collé-Paillot, Fabienne; Edwards-Lévy, Florence; Lévy, M.-C.

doi:10.1016/s0021-9797(03)00140-1

Cited by 27 publications

(15 citation statements)

References 7 publications

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“…In each case the membrane material remained within the elastic domain. We showed in a previous work [1] that the initial concentration of the capsule inner liquid results from a Donnan equilibrium. This implies that the capsule can be sligthly overinflated but not underinflated ͑1 Ͻ s ഛ 1.05͒.…”

Section: Methodsmentioning

confidence: 92%

“…The role of the capsules is to transport, protect and control the release of the encapsulated substance. The membrane properties are thus of major practical interest: osmotic properties govern the mass transfer through the membrane [1] and mechanical properties control the capacity of capsule deformation [2]. However, their determination is a challenging problem, since the membrane is available only in the form of capsules and not as large sheets of material suitable for classical experimental tests.…”

Section: Introductionmentioning

confidence: 99%

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Compression of a capsule: Mechanical laws of membranes with negligible bending stiffness

Risso

Carin

2004

Phys. Rev. E

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The compression of a capsule between two plates is considered. The problem is solved numerically for a capsule made of an incompressible liquid drop surrounded by a thin elastic membrane which has a negligible bending stiffness. Numerical results are provided for three different mechanical laws of the membrane. By considering elastic moduli independent of the deformation, we show that the isotropic dilation plays the major role. In particular, an asymptotic behavior independent of the shear modulus is found for large deformations. For more complex models, the deformation limits beyond which the variation of elastic moduli starts to play a role are examined. The results indicate that the distinction between the different models requires a careful inspection of both small and large deformations. The theoretical predictions are compared with experimental results. For millimetric capsules with membranes made of covalently linked human serum albumin and alginate, the best agreement is obtained by considering that the elastic moduli are independent of the deformation and range from 0.1 to 4 N/m.

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Section: Methodsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Compression of a capsule: Mechanical laws of membranes with negligible bending stiffness

Risso

Carin

2004

Phys. Rev. E

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“…A positive pressure difference may occur between inside and outside of the capsule. 2 To our knowledge there has been no direct experimental study of the effect of internal pressure on capsule deformation in shear flow. Other instances are found in bioengineering applications 1 where the membrane is semipermeable, i.e., permeable to small molecules such as water or small ions but impermeable to large molecules.…”

Section: Introductionmentioning

confidence: 99%

Deformation of a capsule in simple shear flow: Effect of membrane prestress

Lac

Barthès-Biesel

2005

Physics of Fluids

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We investigate the effect of an initial isotropic prestress on the mechanics of a spherical capsule freely suspended in a simple shear flow. The capsule consists of a drop of liquid enclosed by a very thin hyperelastic membrane. A sufficient prestress may prevent the buckling instability that arises at low shear rates when the membrane bending resistance is neglected. A small perturbation analysis of the capsule deformation is first obtained for small prestress and weak viscous stresses. When the viscous shear stress and the preinflation are large, a numerical model of the capsule deformation shows how prestress decreases the capsule deformation for a given shear rate and how it significantly increases the elastic tension in the membrane at a given deformation level. These results may help the experimentalists to detect the presence of an osmotic pressure difference in a semipermeable capsule.

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“…This observation can mean that the polymer is mainly adsorbed to the wall of the capsules and does not fill the interior completely. However, as PAA is a weak polyelectrolyte, a Donnan equilibrium can be established across the semi‐permeable membrane of capsules leading to an encapsulated solution with a pH shifted into the acidic region 38,39. At this pH, the fluorescence of the polymer is significantly decreased and that would explain why the inner part of the capsule is generally weakly fluorescent.…”

Section: Resultsmentioning

confidence: 99%

Defined Picogram Dose Inclusion and Release of Macromolecules using Polyelectrolyte Microcapsules

Déjugnat

Haložan

Sukhorukov

2005

Macromol. Rapid Commun.

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Summary: Reversible pH‐induced swelling of (PAH/PSS) polyelectrolyte microcapsules is accompanied by increased porosity, making them permeable to poly(acrylic acid) (PAA) at pH values higher than 11.2. This pH‐switchable permeability was used to encapsulate the polyanion in alkaline conditions. Relationship between starting PAA concentration in solution and amount finally being encapsulated has been established and can be used further as calibration curve. A desired amount of encapsulated polymer in the picogram range per capsule can be achieved. The loaded capsules were then used as microreactors by forming a complex between the PAA and Ca2+ ions.General scheme for pH‐induced encapsulation of (PAA) in alkali condition by switching their permeability.magnified imageGeneral scheme for pH‐induced encapsulation of (PAA) in alkali condition by switching their permeability.

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Rates of transport through a capsule membrane to attain Donnan equilibrium

Cited by 27 publications

References 7 publications

Compression of a capsule: Mechanical laws of membranes with negligible bending stiffness

Compression of a capsule: Mechanical laws of membranes with negligible bending stiffness

Deformation of a capsule in simple shear flow: Effect of membrane prestress

Defined Picogram Dose Inclusion and Release of Macromolecules using Polyelectrolyte Microcapsules

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