ζ-Potential analyses using micro-electrical field flow fractionation with fluorescent nanoparticles

Abstract

Increasingly growing application of nanoparticles in biotechnology requires fast and accessible tools for their manipulation and for characterization of their colloidal properties. In this work we determine the zeta-potentials for polystyrene nanoparticles using micro electrical field flow fractionation (μ-EFFF) which is an efficient method for sorting of particles by size. The data obtained by μ-EFFF were compared to zeta potentials determined by standard capillary electrophoresis. For proof of concept, we used polystyrene nanoparticles of two different sizes, impregnated with two different fluorescent dyes. Fluorescent emission spectra were used to evaluate the particle separation in both systems. Using the theory of electrophoresis, we estimated the zeta-potentials as a function of size, dielectric permittivity, viscosity and electrophoretic mobility. The results obtained by the μ-EFFF technique were confirmed by the conventional capillary electrophoresis measurements. These results demonstrate the applicability of the μ-EFFF method not only for particle size separation but also as a simple and inexpensive tool for measurements of nanoparticles zeta potentials.

Dynamic Light Scattering Based Microelectrophoresis: Main Prospects and Limitations

“…[128] In fact, changes in the particle size and ζ potential in parallel are routinely followed to additionally support insights about the interaction of given entities, and a similar combinatorial principle could be applied with numerous other experimental techniques. Some of these methods that were used in combination with the DLS electrophoresis so as to gain more profound insights into the mechanisms of the investigated physicochemical transformations have been small angle x-ray scattering (SAXS), [129] circular dichroism (CD), [130] isothermal titration calorimetry, [131] microbalance, rheological, and conductivity analyzers, [132–137] flow fractionation technologies, [138] various infrared spectroscopies, [139,140] x-ray photoelectron spectroscopy, [141] nuclear magnetic resonance, [142] UV-vis spectroscopy, [143] electron spin resonance spectroscopy, [144] surface enhanced Raman spectroscopy, [145] a range of electron, optical, and atomic force microscopic techniques, [146–148] and many other. The main risk, however, is that the complemented methods may give contrasting and incompatible information.…”

Electrophoretic methods for separation of nanoparticles

“…Nilsson et al [20] reviewed applications of nanoparticles in CE. For example, nanoparticles can be used for evaluation of zeta-potentials [21], enantioseparation [22], protein separations [23], genotyping by affinity CE [24], DNA sequencing [25] or electrokinetic chromatography [26]. Clearly nanoparticles can enhance separation of molecules [27 -29].…”

Analytical methods for separating and isolating magnetic nanoparticles

“…For example, electrophoretic mobilities are converted to zeta potentials (z) and retardation coefficient (kR, where R is the particle radius and k the reciprocal Debye length) values. 34,[96][97][98] The smaller electrical field (0 to 2 V) and range of channel dimensions (several mm) in ElFFF significantly reduce the risk of particle damage. Interest has now shifted to metal oxide mixtures including iron oxide.…”

“…34 Electrical Field-Flow Fractionation (ElFFF) separates analytes based on their electrophoretic mobility and size but without the drawbacks of CE. 34,[96][97][98] The smaller electrical field (0 to 2 V) and range of channel dimensions (several mm) in ElFFF significantly reduce the risk of particle damage. 99 Moreover, the mobile phase is generally water, eliminating some of the complications of using buffers with nanoparticles.…”