Simultaneous sizing and electrophoretic mobility measurement of sub‐micron particles using Brownian motion

Abstract

The size and surface chemistry of micron scale particles are of fundamental importance in studies of biology and air particulate pollution. However, typical electrophoretic measurements of these and other sub-micron scale particles (300 nm – 1 μm) cannot resolve size information within heterogeneous mixtures unambiguously. Using optical microscopy, we monitor electrophoretic motion together with the Brownian velocity fluctuations—using the latter to measure size by either the Green-Kubo relation or by calibration from known size standards. Particle diameters are resolved to ±12% with 95% confidence. Strikingly, the size resolution improves as particle size decreases due to the increased Brownian motion. The sizing ability of the Brownian assessed electrophoresis method described here complements the electrophoretic mobility resolution of traditional capillary electrophoresis.

Influence of ionic constituents and electrical conductivity on the propagation of charged nanoscale objects in passivated gel electrophoresis

“…These values are close to theoretical calculations of μ e , as reported by Hill who cites the work of Allison, et al . and Palanisami and Miller . Using our measured E c (Fig.…”

Rapid morphological characterization of isolated mitochondria using Brownian motion

“…The capillary was preconditioned with NaOH and buffer as previously described. 17 The mitochondria are observed in the capillary using an inverted microscope (IX-71; Olympus, Central Valley, PA, USA) with a 1.6× internal magnification and a 20× phase contrast objective (UPlanFl; Olympus). We intentionally choose a low 0.40 NA (and consequently low magnification) objective lens to increase the depth of field.…”

“…For the case of a sphere, the relation goes as 17 $$d=\frac{\Gamma }{{\sigma }_v^2}$$$$\Gamma =\frac{2k_{\mathrm{normalB}}TF}{3\pi \eta }$$ where d is the particle diameter and Γ is a constant which depends on viscosity ( η ), temperature ( T ), Boltzmann's constant ( k B ) and camera frame rate ( F ). By determining Γ by calibration against a bead standard, spherical particles can be sized from their ${\sigma }_v^2$ by using eqn (4).…”

Assessment of submicron particle zeta potential in simple electrokinetic microdevices

“…Characterizing the and μ EP allows assessing particle surface and morphological properties, which can be related to important biological attributes . Furthermore, knowing the enables a better selection of the proper separation technique to be used for a given particle sample or application.…”

“…Furthermore, knowing the enables a better selection of the proper separation technique to be used for a given particle sample or application. Significant efforts have been devoted to the characterization of and μ EP for microparticles and nanoparticles . White et al.…”