Integration Of Localized Stacking And Microchip Gel Electrophoresis For DNA Analysis

The detection capability of a microfluidic system is limited due to the low abundance of the sample and the limited injection sample quantity. It has been demonstrated that micro-nanofluidic effects can be used for high efficient on chip stacking of species from small samples. Integration of efficient online preconcentration with microchip electrophores is fundamental for improving the performance of microfluidic chip analysis system. Concentration polarization effects at the micro-nanofluidic interface is to be integrated with chip gel electrophoresis system to improve the performance of DNA analysis.In the first chapter of this paper, sample introduction of the microfluidic chip electrophoresis, development nanofluic concentration, online preconcentration and separation and non-gel sieving capillary electrophoresis were reviewd.In the second chapter of this paper, a capillary chip electrophoresis system on quartz capillary coupled with sampling fracture was constructed, and the width of the fracture was estimated by conductance detection and theoretical model. Introduction of negatively charged probe through the fracture was investigated, and correlated with the width. Under optimized condition, separation efficiency of 2.72 × 105 plate number/m for DNA gel electrophoresis separation was demonstrated with injection voltage 100 V and injection time 9 s.In the third chapter of this paper, both sampling fracture and Nafion nanofluidic interface was introduced in a capillary chip gel electrophoresis system for improving the efficiency of separation and detection. Localized enrichment and electrokinetic transportation of the enriched plug of DNA on Nafion interface and etching interface were implemented under HCl treatment and screening matrix conditions. The test showed that the concentration effect of Nafion interface on the capillary fracture remained under HCl treatment. Finally the DNA injection, nanofluidic concentration and sieving separation and laser induced fluorescence detection were successfully demonstrated in the chip electrophoresis system with the fracture sampling and micro-nano interface. The DNA response was increased approximately 200 times after 1 min of preconcentration, as compared with that obtained only by the fracture sampling.This work shows fracture sampling and nanofluidic preconcentration is feasible for improving the performance of capillary based chip electrophoresis of DNA, which is characterized in simple and cost-effective, without involving any microfabrication process. The performance of DNA marker separation after nanofluidic concentration remains to be further improved.