Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation

Williams, P. Stephen; Carpino, Francesca; Zborowski, Maciej

doi:10.1098/rsta.2010.0133

Cited by 25 publications

(16 citation statements)

References 49 publications

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“…The calculated R converge on those predicted by Eq. (13) as α approaches zero, as expected, but the wide range of α makes it difficult to discern the difference between the solutions when α<λ≪1, which is the region with which we are concerned here. Shendruk et al [47] later presented experimental results supporting the model, but again, the experiments were not relevant to the typical range of stericcorrected normal mode FFF.…”

Section: Influence Of Steric Correction On Retention and Nonequilibrimentioning

confidence: 71%

“…(13) or Eq. (14) to very high field strength or cross flow where λ approaches zero puts retention into the steric mode.…”

Section: Influence Of Steric Correction On Retention and Nonequilibrimentioning

confidence: 96%

“…We suppose that Eqs. (12) and (13) are acceptably accurate for some range of α/λ, and consider the case of strong retention where λ≪1 and α≪1. The retention ratio for both Sym-FlFFF and As-FlFFF is then given by…”

Section: Influence Of Steric Correction On Retention and Nonequilibrimentioning

confidence: 98%

“…Many different fields have been utilized for FFF including gravitational [4], centrifugal [5][6][7], thermal gradient [8,9], electrical [10,11], and magnetic [12,13]. Any field that interacts with a sample material property to drive the particles across the channel thickness may be used.…”

Section: Introductionmentioning

confidence: 99%

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Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation

Williams

2015

Anal Bioanal Chem

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In asymmetrical flow field-flow fractionation (As-FlFFF), only the membrane-covered accumulation wall is permeable to fluid; the opposite channel wall is impermeable. Fluid enters the channel at the inlet and exits partly through the membrane-covered accumulation wall and partly through the channel outlet. This means that not only does the volumetric channel flow rate decrease along the channel length as fluid exits through the membrane but also the cross-channel component to fluid velocity must approach zero at the impermeable wall. This dependence of cross-channel fluid velocity on distance across the channel thickness influences the equilibrium concentration profile for the sample components introduced to the channel. The concentration profile departs from the exponential profile predicted for the ideal model of field-flow fractionation. This influences both the retention ratio and the principal contribution to bandspreading--the nonequilibrium contribution. The derivation of an equation for the nonequilibrium bandspreading parameter χ in As-FlFFF is presented, and its numerical solution graphed. At high retention, it is shown that the solutions for both retention ratio R and χ converge on those for the ideal model, as expected. At lower levels of retention, the departures from the ideal model are significant, particularly for bandspreading. For example, at a level of retention corresponding to a retention parameter λ of 0.05, R is almost 4% higher than for the ideal model (0.28047 as compared to 0.27000) but the value of χ is almost 60% higher. The equations presented for both R and χ include a first-order correction for the finite size of the particles--the steric exclusion correction. These corrections are shown to be significant for particle sizes eluting well before steric inversion. For example, particles of half the inversion diameter are predicted to elute 25% slower and to show almost 40% higher bandspreading when steric effects are not accounted for. The work presented contributes to the fundamental theory of As-FlFFF and allows quantitative prediction of both retention and bandspreading at all levels of retention.

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Section: Influence Of Steric Correction On Retention and Nonequilibrimentioning

confidence: 71%

“…(13) or Eq. (14) to very high field strength or cross flow where λ approaches zero puts retention into the steric mode.…”

Section: Influence Of Steric Correction On Retention and Nonequilibrimentioning

confidence: 96%

Section: Influence Of Steric Correction On Retention and Nonequilibrimentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation

Williams

2015

Anal Bioanal Chem

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“…The technique belongs to a large family of the field-flow fractionation (FFF) analytical techniques, 17–18 here specialized for the characterization of magnetic micro- and nano-particles. 19 The effort in the past was directed towards a programmed field operation to measure the mass of the magnetic species per microparticle and its distribution in the sample. 19–21 The purpose of this study was to evaluate the system using a simpler on-off field operation for potential future applications requiring removal of contaminating weakly magnetic material prior to structural and magnetization analysis, such as by small angle X-ray scattering.…”

Section: Introductionmentioning

confidence: 99%

A Quantitative Determination of Magnetic Nanoparticle Separation Using On-Off Field Operation of Quadrupole Magnetic Field-Flow Fractionation (QMgFFF)

et al. 2013

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Quadrupole Magnetic Field-Flow Fractionation (QMgFFF) is a technique for characterization of sub-micrometer magnetic particles based on their retention in the magnetic field from flowing suspensions. Different magnetic field strengths and volumetric flow rates were tested using on-off field application and two commercial nanoparticle preparations that significantly differed in their retention parameter, λ (by nearly 8-fold). The fractograms showed a regular pattern of higher retention (98.6% v. 53.3%) for the larger particle (200 nm v. 90 nm) at the higher flow rate (0.05 mL/min v. 0.01 mL/min) at the highest magnetic field (0.52 T), as expected because of its lower retention parameter. The significance of this approach is a demonstration of a system that is simpler in operation than a programmed field QMgFFF in applications to particle mixtures consisting of two distinct particle fractions. This approach could be useful for detection of unwanted particulate contaminants, especially important in industrial and biomedical applications.

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Magnetophoresis: Fundamentals and Applications

Zborowski

Chalmers

2015

Wiley Encyclopedia of Electrical and Electronics Engineering

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The term “magnetophoresis” has been proposed to describe the behavior of a magnetic particle moving through a viscous medium under the influence of an external magnetic field. Its origin can be traced to a similar term used to describe particle motion in a viscous medium under the influence of an electric field, “electrophoresis.” The number of publications on magnetophoresis has rapidly increased during the last 10 years primarily due to a burgeoning interest in its applications to biomedical research and clinical diagnostics and therapy. The appealing feature of magnetophoresis is that under well‐controlled conditions it provides a means for gentle cell separation in its natural milieu that could be both highly specific and highly sensitive at a relatively low cost with respect to the separation equipment. The increasing interest in single‐cell biology in health and disease and the rapidly improving sensitivity of molecular biology methods in applications to single‐cell genomic analysis put a special emphasis on high quality, high volume, and relatively inexpensive cell separation methods, such as those provided by cell magnetophoresis in microfluidic channels. The growth in magnetophoresis research and applications is aided by a synergy between materials science, nanoparticle synthesis and characterization, micro‐ and nanofluidic engineering, experimental and computational fluid dynamics research, and physics of high magnetic fields. This leads to emerging applications, such as detection of paramagnetic impurities in diamagnetic samples and biomagnetic cell separations. These are areas of magnetophoresis applications that will likely continue to rapidly grow.

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Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation

Cited by 25 publications

References 49 publications

Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation

Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation

A Quantitative Determination of Magnetic Nanoparticle Separation Using On-Off Field Operation of Quadrupole Magnetic Field-Flow Fractionation (QMgFFF)

Magnetophoresis: Fundamentals and Applications

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