Analysis of magnetic nanoparticles using quadrupole magnetic field-flow fractionation

Carpino, Francesca; Moore, Lee R.; Zborowski, Maciej; Chalmers, Jeffrey J.; Williams, P. Stephen

doi:10.1016/j.jmmm.2005.01.071

Cited by 51 publications

(37 citation statements)

References 14 publications

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“…To minimize this phenomenon and in turn to increase the separation rate, very thin channels with low volumetric capacities are used such as trapezoidal geometrically shaped channels. This type of channel shape versus a rectangular shape advantageously allows an extra means to control the longitudinal flow velocity, where the breadth decreases continuously towards the channel outlet, which 135 creates a possibility to level out the steep linear velocity gradients that can materialize in the rectangular channel. 122 The ultrafiltration membrane also needs to be carefully considered as the cut-off range and molecular interaction with the filter material may significantly influence the potential sample loss and recovery.…”

Section: Asymmetrical Flow Field Flow Fractionationmentioning

confidence: 99%

Protein aggregation: Pathways, induction factors and analysis

Mahler

Frieß

Grauschopf

et al. 2009

Journal of Pharmaceutical Sciences

764

635

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Section: Asymmetrical Flow Field Flow Fractionationmentioning

confidence: 99%

Protein aggregation: Pathways, induction factors and analysis

Mahler

Frieß

Grauschopf

et al. 2009

Journal of Pharmaceutical Sciences

764

635

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“…This was also made of 15.24 cm tall plates, but of 1.91 cm thickness. A schematic of the cross section of the electromagnet plates and coils has been shown in the literature (Carpino et al 2005b). A photograph of the quadrupole electromagnet is shown in figure 1a.…”

Section: Methodsmentioning

confidence: 99%

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

Williams

Carpino

Zborowski

2010

Phil. Trans. R. Soc. A.

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Quadrupole magnetic field-flow fractionation is a relatively new technique for the separation and characterization of magnetic nanoparticles. Magnetic nanoparticles are often of composite nature having a magnetic component, which may be a very finely divided material, and a polymeric or other material coating that incorporates this magnetic material and stabilizes the particles in suspension. There may be other components such as antibodies on the surface for specific binding to biological cells, or chemotherapeutic drugs for magnetic drug delivery. Magnetic field-flow fractionation (MgFFF) has the potential for determining the distribution of the magnetic material among the particles in a given sample. MgFFF differs from most other forms of field-flow fractionation in that the magnetic field that brings about particle separation induces magnetic dipole moments in the nanoparticles, and these potentially can interact with one another and perturb the separation. This aspect is examined in the present work. Samples of magnetic nanoparticles were analysed under different experimental conditions to determine the sensitivity of the method to variation of conditions. The results are shown to be consistent and insensitive to conditions, although magnetite content appeared to be somewhat higher than expected.

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“…Numerical methods were used for solution of the integrals in Eq. (12). Note that λ 0 for Sym-FlFFF is defined as for AsFlFFF in terms of cross-channel fluid velocity component at the membrane, remembering that ideally this is constant across the channel thickness.…”

Section: The Retention Ratiomentioning

confidence: 99%

“…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%

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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Analysis of magnetic nanoparticles using quadrupole magnetic field-flow fractionation

Cited by 51 publications

References 14 publications

Protein aggregation: Pathways, induction factors and analysis

Protein aggregation: Pathways, induction factors and analysis

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

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

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