Determination of individual microsphere properties by capillary electrophoresis with laser-induced fluorescence detection

Abstract

Capillary electrophoresis with postcolumn laser-induced fluorescence detection was used to individually detect 6.0, 1.0, 0.5, and 0.2 num diameter polystyrene microspheres and individually measure their electrophoretic mobility. The analysis of a nanoliter-size volume from a microsphere suspension results in an electropherogram characterized by several narrow spikes in a well-defined migration time window. Each spike is associated with one microsphere because, when one single microsphere is introduced into the capillary by micromanipulation, the electropherogram has only one spike in the same migration time window. The distributions of individual measurements resulting from an electropherogram were used to evaluate the reproducibility from run to run, observe the effect of sodium dodecyl sulfate (SDS) added to the running buffer, and to investigate the origin of electrophoretic dispersion. As expected from the interactions between microspheres and SDS, the addition of this surfactant to the running buffer narrowed the range and shifted the average electrophoretic mobility to more negative values. After evaluating common sources of broadening in capillary electrophoresis, electrophoretic dispersion was attributed to microsphere heterogeneity. Unlike electropherograms displaying Gaussian-like profiles, the two-dimensional representations of the individual measurements provide a new alternative to evaluate and study electrophoretic-related properties of microspheres.

Capillary zone electrophoresis of graphene oxide and chemically converted graphene

“…All spikes in the electropherograms are considered to be aggregates that are stacks of graphene nanosheets and therefore big enough to cause a spike by the detector. This is also consistent with the spikes observed in the CE analysis of single 200-1000 nm sized sulphated polystyrene particles [23].…”

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

“…mitochondria) [1] and colloidal [2] particles on the ~1 μm size scale. Increasingly, the electrophoretic mobility is being measured simultaneously with other techniques such as fluorescent intensity [3], light scattering [4] and mass spectrometry [5] to form 2-D analyses. Despite the progress made in these synergistic 2-D studies, extracting the electrophoretic mobility as a function of particle size is still non-trivial; the particles must first be separated by size, and then electrophoretic measurements taken.…”

“…Despite this, the correlation of size with the electrophoretic properties of individual mitochondria is relatively unstudied. In this regard, capillary electrophoresis (CE) in concert with laser induced fluorescence (LIF) [3] is a useful technique which can quantify the number of fluorescent molecules associated with an individual particle. However, in addition to being correlated with size, other aspects of the particle may influence fluorescent dye binding.…”

Capillary electrophoresis monitors changes in the electrophoretic behavior of mitochondrial preparations

“…In contrast to the electrical surface charge, morphology and size do not seem to have a strong effect on the electrophoretic mobility of an organelle. Size-dependent electrophoretic separations may be accomplished if a sieving matrix is added to the separation media as has been done for non-biological particles [25][26][27][28][29][30][31][32].…”