Gold nanoparticle-enhanced microchip capillary electrophoresis.

We describe here the use of gold nanoparticles in conjunction with chip-based capillary electrophoresis to improve the selectivities between solutes and to increase the efficiency of the separation. We coated the microchannel wall of a microfluidic device with a layer of poly(diallyldimethylammonium chloride) (PDADMAC) and then collected on it citrate-stabilized gold nanoparticles. The resolutions and the plate numbers of the solutes were doubled in the presence of the gold nanoparticles. Such selectivity improvements reflect changes in the observed mobility accrued from interactions of solutes with the particle surface. The electrochemical detection and the quantitation of the solutes were not effected by the PDADMAC and the gold nanoparticles.