Highly efficient approach for characterizing nanometer-sized gold particles by capillary electrophoresis

This paper demonstrates that capillary electrophoresis (CE) can be employed for characterizing the sizes of nanometer-scale gold particles. We characterized the gold nanoparticles by effecting CE separation using a buffer of SDS (70 mM) and 3-cyclohexylamino-1-propanesulfonic acid (CAPS; 10 mM) at pH 11.0 and an applied voltage of 18 kV and obtained a linear relationship (R-2 > 0.99) between electrophoretic mobilities and size for nanoparticles whose diameters fall in the regime from 5.0 +/- 0.5 to 41.2 +/- 3.3 nm; the relative standard deviations of these electrophoretic mobilities are < 0.8%. We evaluated the feasibility of employing these separation conditions for the size characterization by of gold nanoparticle, samples that were synthesized by a rapid microwave heating method. We confirmed that this CE method is a valid one for size characterization by comparing the results obtained by CE with those provided by scanning electron microscopy (SEM): a good correlation exists between these two techniques. Our results demonstrate that CE can be employed to accelerate the analysis of the sizes of nanomaterials. (C) 2004 Elsevier B.V. All rights reserved.