Electrophoretic Interpretation of PEGylated NP Structure with and without Peripheral Charge

Hill, Reghan J.; Li, Fei; Doane, Tennyson L.; Burda, Clemens

doi:10.1021/acs.langmuir.5b02809

Cited by 10 publications

(24 citation statements)

References 31 publications

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“…However, the mobility-ionic strength relationship for these NPs seems more likely to reflect a CM-PEG layer that changes its structure/extent with the bulk electrolyte ionic strength, since an acid-dissociation-only model did not adequately capture all the available experimental trends over the full range of ionic strengths. Therefore, the present study of charge regulation supports the recent interpretation of Hill et al [22], whereby the CM groups were taken to be fully dissociated and the corona structure was varied with the electrolyte ionic strength.…”

Section: Discussionsupporting

confidence: 88%

“…Ideally, these geometrical parameters should be prescribed using independent knowledge of the PEG-chain size and conformation, or from the hydrodynamic size, which may be available from diffusion experiments, such as dynamic light scattering, fluorescence correlation spectroscopy or sedimentation. In this study, they are set to physically acceptable constants that also furnished reasonable predictions and interpretations of experimental data [22].…”

Section: Resultsmentioning

confidence: 97%

“…These data were measured with the particles dispersed in TAE (squares) and PBS (circles) buffers that were diluted with reverse osmosis (RO) water [22,23]. The rectangles identify the ranges of ionic Table 2: Electrolyte-ion and corona charge-dissociation parameters: λ j are the limiting conductivities used to prescribe ion mobilities.…”

Section: Weak-acid/dissociation-only Charge Regulationmentioning

confidence: 99%

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Corona charge regulation in nanoparticle electrophoresis

Hill¹

2015

Proc. R. Soc. A.

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Nanoparticle size and charge play key roles in bioconjugation chemistry, imaging, and drug-delivery. Although the electrophoretic mobility and hydrodynamic size are routinely measured, interpreting these data can be extremely difficult. Here, the challenge is addressed via an electrokinetic model for spheres bearing a soft amphoteric corona, the charge of which is regulated by a multicomponent electrolyte. The model is applied to nanoparticles with a metallic core to which are grafted poly(ethylene glycol) (PEG) chains with either weak acid or amphiprotic end groups. The results elucidate the separate roles of electrolyte pH and ionic strength on the electrophoretic mobility and diffusion coefficient. In this study, the forces were evaluated directly, rather than from the Stokeslet velocity disturbances. While second-order convergence was demonstrated by both methods, the direct approach, which uses only the inner part of the global solution, furnished superior accuracy and robustness. This may benefit future attempts to model the dielectric and electroacoustic properties of these complex nanoparticulates.

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Section: Discussionsupporting

confidence: 88%

Section: Resultsmentioning

confidence: 97%

Section: Weak-acid/dissociation-only Charge Regulationmentioning

confidence: 99%

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Corona charge regulation in nanoparticle electrophoresis

Hill¹

2015

Proc. R. Soc. A.

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“…Thus, theoretical interpretations of the free-solution electrophoretic mobility of soft nanoparticles have benefitted from models of the corona architecture 11,14 . Nanoparticle coronas reflect the polymer attachment mechanism (e.g., physical adsorption versus terminal grafting), surface curvature (nanoparticle radius is generally comparable to ligand size), and a non-uniform distribution of ligand charge (e.g., PEG ligands bearing charged end groups 10 ).…”

mentioning

confidence: 99%

“…The linearized equations for the so-called E-and V -problems are then superposed to satisfy the boundary conditions and particle equation of motion. Technical details, including those accounting for charge-regulation chemistry, are available elsewhere 14 , and so only essential modifications to the earlier formulations are highlighted here.…”

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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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