Electrokinetic characterization of individual nanoparticles in nanofluidic channels

Wynne, Thomas M.; Dixon, Alexander H.; Pennathur, Sumita

doi:10.1007/s10404-011-0884-4

Cited by 12 publications

(24 citation statements)

References 29 publications

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“…37,38 However, EDLs generated by the particle and by channel walls interact with each other, which affects mobility especially when channel height is comparable to thickness of EDL. Therefore, particle mobility should in fact deviate from that predicted by superposition of electrophoretic and electro-osmotic mobility.…”

Section: Particle Mobilitymentioning

confidence: 99%

Electrophoretic mobility of a spherical nanoparticle in a nanochannel

2014

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Numerical simulation is used to calculate accurately the electrophoretic mobility of a charged spherical nanoparticle confined in a nanochannel, under a weakly applied electric field. Classic models for electrophoretic mobility are valid only in the linear regime of small particle zeta potential, and for an unbounded fluid domain. However, these models fail to predict the electrophoretic mobility measured experimentally in bounded nanochannels. We adopt asymptotically expanded formulations and solve the fully coupled equations on a 3D finite element domain. Factors affecting particle mobility include electrolyte concentration, channel size, and zeta potentials on both the particle surface and channel walls. Specifically, spherical particles are examined with diameters 2a = 10 and 50 nm, in a 100 nm high channel. The non-dimensional electric double layers were varied between 0.1 < κa < 100. The results indicate that the mobility of a particle located at the nanochannel centerline agrees to within 1% of the average mobility of a particle distributed transversely throughout the nanochannel. Furthermore, confinement by the nanochannel walls was found to affect greatly nanoparticle mobility. As a result, it is feasible to use nanochannels to separate two different size nanoparticles, even when the particles have equal zeta potentials. Finally, a new method is proposed to estimate accurately particle and wall zeta potentials by contrasting the observed differences in mobility between observed in two different height channels. C 2014 AIP Publishing LLC. [http://dx.

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Section: Particle Mobilitymentioning

confidence: 99%

Electrophoretic mobility of a spherical nanoparticle in a nanochannel

2014

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“…16–18 The challenge here is that existing theories applicable to microscale systems do not necessarily describe fundamental nanoscale phenomena. Theories and experimental studies relevant to nanoscale electrokinetic separations have appeared in several reports.…”

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“…36 Liu et al 37 were able to separate silver nanoparticles (AgNPs) in the presence of an SDS surfactant using CE; no separation was achievable using free solution electrophoresis. While there have been reports on the separation of spherical nanoparticles using conventional or microchip CE, only a few studies have reported the electrophoretic transport behavior of noble metal nanoparticles in nanofluidic domains; 17,18,38 these studies used glass-based devices, however.…”

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confidence: 99%

Electrophoretic Separation of Single Particles Using Nanoscale Thermoplastic Columns

et al. 2016

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Phenomena associated with microscale electrophoresis separations cannot, in many cases, be applied to the nanoscale. Thus, understanding the electrophoretic characteristics associated with the nanoscale will help formulate relevant strategies that can optimize the performance of separations carried out on columns with at least one dimension below 150 nm. Electric double layer (EDL) overlap, diffusion, and adsorption/desorption properties and/or dielectrophoretic effects giving rise to stick/slip motion are some of the processes that can play a role in determining the Efficiency of nanoscale electrophoretic separations. We investigated the performance characteristics of electrophoretic separations carried out in nanoslits fabricated in poly(methyl methacrylate), PMMA, devices. Silver nanoparticles (AgNPs) were used as the model system with tracking of their transport via dark field microscopy and localized surface plasmon resonance. AgNPs capped with citrate groups and the negatively charged PMMA walls (induced by O2 plasma modification of the nanoslit walls) enabled separations that were not apparent when these particles were electrophoresed in microscale columns. The separation of AgNPs based on their size without the need for buffer additives using PMMA nanoslit devices is demonstrated herein. Operational parameters such as the electric field strength, nanoslit dimensions, and buffer composition were evaluated as to their effects on the electrophoretic performance, both in terms of Efficiency (plate numbers) and resolution. Electrophoretic separations performed at high electric field strengths (>200 V/cm) resulted in higher plate numbers compared to lower fields due to the absence of stick/slip motion at the higher electric field strengths. Indeed, 60 nm AgNPs could be separated from 100 nm particles in free solution using nanoscale electrophoresis with 100 μm long columns.

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“…11,12 For example, a depletion of 42 nm particles within 40 nm of the wall in a nanochannel was found for λ D < 1 nm. 12 Whether these represent new findings is still under debate. Previous study reported that the nanoparticle distribution obtained by the evanescent wave-based method is blurred by the camera exposure time and the system noise.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Behavior of Nanoparticles in Extended Nanospace Measured by Evanescent Wave-Based Particle Velocimetry

2015

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The transport and behavior of nanoparticles, viruses, and biomacromolecules in 10-1000 nm confined spaces (hereafter "extended nanospaces") are important for novel analytical devices based on nanofluidics. This study investigated the concentration and diffusion of 64 nm nanoparticles in a fused-silica nanochannel of 410 nm depth, using evanescent wave-based particle velocimetry. We found that the injection of nanoparticles into the nanochannel by pressure-driven flow was significantly inhibited and that the nanoparticle diffusion was hindered anisotropically. A 0.2-pN repulsive force induced by the interaction between the nanoparticles and the channel wall is proposed as the dominant factor governing the behavior of nanoparticles in the nanochannel, on the basis of both experimental measurements and theoretical estimations. The results of this study will greatly further our understanding of mass transfer in extended nanospaces.

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Electrokinetic characterization of individual nanoparticles in nanofluidic channels

Cited by 12 publications

References 29 publications

Electrophoretic mobility of a spherical nanoparticle in a nanochannel

Electrophoretic mobility of a spherical nanoparticle in a nanochannel

Electrophoretic Separation of Single Particles Using Nanoscale Thermoplastic Columns

Behavior of Nanoparticles in Extended Nanospace Measured by Evanescent Wave-Based Particle Velocimetry

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