Sensitive and rapid analysis of plasmid DNA topology isoforms by capillary gel electrophoresis with laser induced fluorescence in uncoated capillary.

The work describes the use of SYBR Gold to improve the detection sensitivity of plasmid DNA topoisomers by capillary gel electrophoresis with laser induced fluorescence in an uncoated capillary. The impact of different dyes, including ethidium bromide, SYBR Green and SYBR Gold, was compared based on detection and separation of DNA plasmid topoisomers. Use of SYBR Gold enabled improvement of detection sensitivity by 15-fold while maintaining good separation resolution of the different topoisomers. The baseline dropped with the use SYBR Gold but was overcome by the employment of a capillary with longer ineffective length (40 vs. 20 cm). Separation resolution and reproducibility were impacted by the concentration of SYBR Gold and hydroxypropyl methylcellulose. With the use of a short capillary (10 cm effective length and 50 cm total length), fast separations of supercoiled, linear, open circular, and other isoforms were accomplished within 8 min. Appropriate capillary cleaning with 0.1 M sodium hydroxide/0.1 M hydrochloric acid and capillary storage with 0.1 M hydrochloric acid ensured good separation reproducibility of 217 runs during an extended period of use.