Analysis of double-stranded DNA by microchip capillary electrophoresis using polymer solutions containing gold nanoparticles

The impact of gold nanoparticles (GNPs) on the microchip electrophoretic separation of double-stranded (ds) DNA using
poly(ethylene oxide) (PEO) is described. Coating of the 75-mm separation channel on a poly(methyl methacrylate) (PMMA)
plate in sequence with poly(vinyl pyrrolidone), PEO, and 13-nm GNPs is effective to improve reproducibility and resolution.
In this study, we have also found that adding 13-nm GNPs to 1.5% PEO is extremely important to achieve high resolution
and reproducibility for DNA separation. In terms of the stability of the GNPs, 100 mM glycine–citrate buffer at pH 9.2 is a
good buffer system for preparing 1.5% PEO. The separation of DNA markers V and VI ranging in size from 8 to 2176 base
pairs has been demonstrated using the three-layer-coated PMMA microdevice filled with 1.5% PEO containing the GNPs.
Using these conditions, the analysis of the polymerase chain reaction products of UGT1A7 was complete in 7 min, with the
relative standard deviation values of the peak heights and migration times less than 2.3% and 2.0%, respectively. In
conjunction with stepwise changes of the concentrations of ethidium bromide (0.5 and 5 mg/ml), this method allows
improved resolution and sensitivity for DNA markers V and VI.