Electric-field-induced displacement of charged spherical colloids in compressible hydrogels

Wang, Mu; Hill, Reghan J.

doi:10.1039/b719319j

Cited by 18 publications

(36 citation statements)

References 53 publications

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“…Moreover, Hill & Ostoja-Starzewski (2008) identified a close connection between the steady electrical displacement of charged inclusions embedded in uncharged, incompressible hydrogels. Accordingly, for uncharged, compressible hydrogels, the particle displacement is also independent of the dielectric constant (Wang & Hill 2008).…”

Section: Ii) E-problemmentioning

confidence: 99%

“…However, in contrast to uncharged hydrogels (Hill & Ostoja-Starzewski 2008;Wang & Hill 2008), there exists a hydrostatic force owing to the gradients of osmotic pressure. The mechanical-contact force is due to polymer displacement where, in contrast to uncharged hydrogels, the displacement is coupled to the electrostatic potential.…”

Section: (I) Z -Problemmentioning

confidence: 99%

“…Following Wang & Hill (2008), we adopt ν = 0.2 as a representative value for charged and uncharged hydrogels, e.g. ν ≈ 0.15 for agarose (Freeman et al 1994) and ν ≈ 0.2 for articular cartilage (Jurvelin et al 1997).…”

Section: Electrical Responsementioning

confidence: 99%

“…They calculated the steady electricfield-induced response of a charged, spherical colloid embedded in incompressible, uncharged polymer gels, showing that sub-nanometre displacements prevail under typical experimental conditions. Wang & Hill (2008) extended their model to compressible, but still uncharged, polymer skeletons, predicting displacements that are large enough to register with optical microscopy.…”

Section: Introductionmentioning

confidence: 99%

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Steady electrical and micro-rheological response functions for uncharged colloidal inclusions in polyelectrolyte hydrogels

Mohammadi

Hill

2009

Proc. R. Soc. A.

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The electric-field-induced response of an uncharged colloidal sphere embedded in a quenched polyelectrolyte hydrogel is calculated from a model where the polymer network is treated as an elastic, porous skeleton saturated with an aqueous electrolyte. We present exact analytical solutions for the steady response to a uniform electric field, as well as the steady susceptibility, defined as the ratio of the particle displacement to the strength of an optical or magnetic force. Even though the particle is uncharged, it attains a finite electric-field-induced displacement owing to hydrodynamic coupling with electroosmotic flow. The steady susceptibility decreases with increasing charge and decreasing electrolyte concentration; in general, charge imparts a small correction to the classical theory for an uncharged linearly elastic continuum.

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Section: Ii) E-problemmentioning

confidence: 99%

Section: (I) Z -Problemmentioning

confidence: 99%

Section: Electrical Responsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Steady electrical and micro-rheological response functions for uncharged colloidal inclusions in polyelectrolyte hydrogels

Mohammadi

Hill

2009

Proc. R. Soc. A.

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“…However, high electric-field strengths also manifest in non-linear electrokinetics 7 , and it is presently unknown when and how to distinguish these. Yet another body of work has addressed the electric-fieldinduced dynamics of particles that are permanently adhered to or entrapped in hydrogel networks 1,18,26 ; these studies complement an extensive microrheology literature 25 .…”

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confidence: 99%

Electrokinetics of nanoparticle gel-electrophoresis

Hill

2016

Soft Matter

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Gel-electrophoresis has been demonstrated in recent decades to successfully sort a great variety of nanoparticles according to their size, charge, surface chemistry, and corona architecture. However, quantitative theoretical interpetations have been limited by the number and complexity of factors that influence particle migration. Theoretical models have been fragmented and incomplete with respect to their counterparts for free-solution electrophoresis. This paper unifies electrokinetic models that address complex nanoparticle corona architectures, corona and gel charge regulation (e.g., by the local pH), multi-component electrolytes, and non-linear electrostatics and relaxation effects. By comprehensively addressing the electrokinetic aspects of the more general gel-electrophoresis problem, in which short-ranged steric interactions are significant, a stage is set to better focus on the physicochemical and steric factors. In this manner, it is envisioned that noparticle gelelectrophoresis may eventually be advanced from a nanoparticle-characterization tool to one that explicitly probes the short-ranged interactions of nanoparticles with soft networks, such as synthetic gels and biological tissues. In this paper, calculations are undertaken that identify a generalized Hückel limit for nanoparticles in low-conductivity gels, and a new Smoluchowski limit for polyelectrolyte-coated particles in high-conductivity gels that is independent of the gel permeability. Also of fundamental interest is a finite, albeit small, electrophoretic mobility for uncharged particles in charged gels. Electrophoretic mobilities and drag coefficients (with electroviscous effects) for nanoparticles bearing non-uniform coronas show that relaxation effects are typically weak for the small nanoparticles (radius ≈ 3-10 nm) to which gel-electrophoresis has customarily been applied, but are profound for the larger nanoparticles (radius 40 nm in low conductivity gels) to which passivated gel-electrophoresis experiments have recently been applied. To demonstrate its practical application, the model is applied to (pH charge regulating) carboxylated polystyrene nanospheres in low-density passivated agarose gels (weak steric effects). This furnishes a new theoretical interpretation of literature data for which a finite diffuse-layer-thickness, pH-charge regulation, high charge, and relaxation effects dominate over the steric influences.

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Mechanical Properties of Cellularly Responsive Hydrogels and Their Experimental Determination

et al. 2010

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Hydrogels are increasingly employed as multidimensional cell culture platforms often with a necessity that they respond to or control the cellular environment. Specifically, synthetic hydrogels, such as poly(ethylene glycol)-based (PEG) gels, are frequently utilized for probing the microenvironment’s influence on cell function, as the gel properties can be precisely controlled in space and time. Synthetically tunable parameters, such as monomer structure and concentration, facilitate initial gel property control, while incorporation of responsive degradable units enables cell- and/or user-directed degradation. Such responsive gel systems are complex with dynamic changes occurring over multiple time-scales, and cells encapsulated in these synthetic hydrogels often experience and dictate local property changes profoundly different from those in the bulk material. Consequently, advances in bulk and local measurement techniques are needed to monitor property evolution quantatively and understand its effect on cell function. Here, we review recent progress in cell-responsive PEG hydrogel synthesis and mechanical property characterization.

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Electric-field-induced displacement of charged spherical colloids in compressible hydrogels

Cited by 18 publications

References 53 publications

Steady electrical and micro-rheological response functions for uncharged colloidal inclusions in polyelectrolyte hydrogels

Steady electrical and micro-rheological response functions for uncharged colloidal inclusions in polyelectrolyte hydrogels

Electrokinetics of nanoparticle gel-electrophoresis

Mechanical Properties of Cellularly Responsive Hydrogels and Their Experimental Determination

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