Micro Capillary Electrophoresis Chips with Sample Pre-concentration Devices Utilizing Alternating Current (AC) Electroosmosis Effect

Abstract

The present paper reports a new micro capillary electrophoresis (CE) chip integrated with a sample pre-concentration device utilizing alternating current (AC) electro-osmosis effect. Micro capillary electrophoresis chip has proven to be a powerful tool for sample separation. Not only does it miniaturize the size of the analytical apparatus, but it also executes sample separation in a faster, more efficient way using less samples and reagents. However, the minimum detectable concentration of the samples could still remain an issue. To increase the detectable limits, pre-concentration micro-devices prior to sample separation/detection are of crucial needs. In this study, we utilize a pair of electrodes to generate AC electroosmosis forces such that DNA samples could be focused in a concentration zone, and thus increasing the fluorescence signals. A combination of high-voltage power supplies, high-voltage relays and function generators is used to apply the AC electric signals on the pre-concentration electrodes. Sample plugs in the microchannel are thus concentrated in the pre-concentration zone. Concentrated samples are then injection into the subsequent separation channels. At last, a PMT (Photo-multiplier tube) module is used to detect the fluorescence signals enhanced by the AC electroosmosis effect. Three DNA samples, including -DNA (12 bps), X-174 DNA marker (11 segments) and detection gene for Group A streptococcus (777 bps), have been tested. Successful concentration and separation of these samples have been experimentally verified. The developed micro CE devices with the pre-concentration devices could have significant potential for the analysis of the dilute and low concentration DNA samples.