Ion density deviations in semipermeable ionic microcapsules

Tang, Qiyun; Denton, Alan R.

doi:10.1039/c5cp00974j

Cited by 10 publications

(5 citation statements)

References 43 publications

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“…This model is probably not well suited to objects with thick, highly porous walls like microgels since ions and charges may then be dispersed into the “solid” phase. A treatment of this problem can be found in refs and , for instance. The present coarse-graining strategy is more suited to particles with impermeable walls punctured by a few passageways authorizing ion exchange, like colloidosomes, silica microcapsules, , viral capsids, bilayer vesicles containing nonselective ion channels, or incomplete metallodielectric shells .…”

Section: Debye–hückel Theory For One and Two Shellsmentioning

confidence: 99%

Modeling the Electrostatics of Hollow Shell Suspensions: Ion Distribution, Pair Interactions, and Many-Body Effects

Hallez

Meireles

2016

Langmuir

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Electrostatic interactions play a key role in hollow shell suspensions as they determine their structure, stability, thermodynamics, and rheology and also the loading capacity of small charged species for nanoreservoir applications. In this work, fast, reliable modeling strategies aimed at predicting the electrostatics of hollow shells for one, two, and many colloids are proposed and validated. The electrostatic potential inside and outside a hollow shell with a finite thickness and a specific permittivity is determined analytically in the Debye-Hückel (DH) limit. An expression for the interaction potential between two such hollow shells is then derived and validated numerically. It follows a classical Yukawa form with an effective charge depending on the shell geometry, permittivity, and inner and outer surface charge densities. The predictions of the Ornstein-Zernike (OZ) equation with this pair potential to determine equations of state are then evaluated by comparison to results obtained with a Brownian dynamics algorithm coupled to the resolution of the linearized Poisson-Boltzmann and Laplace equations (PB-BD simulations). The OZ equation based on the DLVO-like potential performs very well in the dilute regime as expected, but also quite well, and more surprisingly, in the concentrated regime in which full spheres exhibit significant many-body effects. These effects are shown to vanish for shells with small thickness and high permittivity. For highly charged hollow shells, we propose and validate a charge renormalization procedure. Finally, using PB-BD simulations, we show that the cell model predicts the ion distribution inside and outside hollow shells accurately in both electrostatically dilute and concentrated suspensions. We then determine the shell loading capacity as a function of salt concentration, volume fraction, and surface charge density for nanoreservoir applications such as drug delivery, sensing, or smart coatings.

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Section: Debye–hückel Theory For One and Two Shellsmentioning

confidence: 99%

Modeling the Electrostatics of Hollow Shell Suspensions: Ion Distribution, Pair Interactions, and Many-Body Effects

Hallez

Meireles

2016

Langmuir

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“…In the resulting hybrid wires, the capsule-based pH-sensors cannot leak out of the polymer filaments. Ions, such as protons (H + ), can pass through the wire outer regions [18,62] and the multilayer capsule shells, [63][64][65][66] and thereby get sensed by the fluorescent pH indicator (Scheme 1c). In other words, ions (-OHand H + ) are allowed to protonate and deprotonate the embedded pH indicator SNARF-1-dextran conjugate.…”

Section: Fabrication Of Ph-sensing Hybrid Organic Wiresmentioning

confidence: 99%

Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer‐Scale Spatial Resolution

Mercato

Moffa

Rinaldi

et al. 2015

Small

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A fundamental issue in biomedical and environmental sciences is the development of sensitive and robust sensors able to probe the analyte of interest, under physiological and pathological conditions or in environmental samples, and with very high spatial resolution. In this work, novel hybrid organic fibers that can effectively report the analyte concentration within the local microenvironment are reported. The nanostructured and flexible wires are prepared by embedding fluorescent pH sensors based on seminaphtho‐rhodafluor‐1‐dextran conjugate. By adjusting capsule/polymer ratio and spinning conditions, the diameter of the fibers and the alignment of the reporting capsules are both tuned. The hybrid wires display excellent stability, high sensitivity, as well as reversible response, and their operation relies on effective diffusional kinetic coupling of the sensing regions and the embedding polymer matrix. These devices are believed to be a powerful new sensing platform for clinical diagnostics, bioassays and environmental monitoring.

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“…The advantage of this approach is that the capsule structure is given at the outset so that the investigation can be focused on the encapsulation process itself. Applications of this method include the analysis of the permeability of encapsulating agents 10 and the investigation of their mechanical and geometrical properties. 11 In a different scheme, the encapsulating structures are not given in advance, but they arise spontaneously through a self-assembly process.…”

Section: Introductionmentioning

confidence: 99%

Encapsulation of spherical nanoparticles by colloidal dimers

Munaò

Costa

Prestipino

et al. 2016

Phys. Chem. Chem. Phys.

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We study by Monte Carlo simulation the coating process of colloidal dimers onto spherical nanoparticles. To this end we investigate a simplified mixture of hard spheres (the guest particles) and hard dimers formed by two tangent spheres of different sizes (the encapsulating agents) in an implicit-solvent representation; in our scheme, the range of effective interactions between the smaller particle in a dimer and a guest sphere depends on their relative size. By tuning the size and concentration of guests, under overall dilute conditions a rich phase behavior emerges: for small sizes and/or low concentrations, the preferred arrangement is compact aggregates (capsules) of variable sizes, where one or few guest particles are coated with dimers; for larger sizes and moderate guest concentrations, other scenarios are realized, including equilibrium separation between a guest-rich and a guest-poor phase. Our results serve as a framework for a more systematic investigation of self-assembled structures of functionalized dimers capable of encapsulating target particles, like for instance bioactive substances in a colloidal dispersion.

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Ion density deviations in semipermeable ionic microcapsules

Cited by 10 publications

References 43 publications

Modeling the Electrostatics of Hollow Shell Suspensions: Ion Distribution, Pair Interactions, and Many-Body Effects

Modeling the Electrostatics of Hollow Shell Suspensions: Ion Distribution, Pair Interactions, and Many-Body Effects

Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer‐Scale Spatial Resolution

Encapsulation of spherical nanoparticles by colloidal dimers

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