Efficient Concentration Of DNA On Fused Silica Capillary Micro-nano Interface

Recently, with the development of microfluidic technology, micro-nanofluidic has been developed rapidly. A micro-nanofluidic chip can be used for enrichment of charged components taking advantage of ion concentration polarization (ICP) effect. This has drawn particular attention due to its importance in biochemical analysis of low concentration samples. Proteins and DNA are the two important biological macromolecules in biochemical samples, but the reported studies on the nanofluidic preconcentration of macromolecules are mainly devoted to proteins, and fewer to DNA. In this work, the potential of nanofluidic preconcentraion of DNA was investigated.In the first chapter of this paper, the latest development of nanofluic concentration was reviewd, the concentration modes as well as concentration rate were emphasized, and typical fabrication methods of nanofluidic device were summarized. The principle of DNA amplification by polymerase chain reaction (PCR) was also introduced briefly.In the second chapter, electrokinetic concentration of DNA at a micro-nano interface formed by HF etching of fused silica capillary was studied systematically using fluorescence imaging. Firstly, the influence of applied voltage was studied. Secondly, the concentration behavior of a PCR amplicon with different dilution factor at the same micro-nano interface was investigated. Up to107times concentration was successfully demonstrated under optimal conditons with the diluted PCR amplicon. Concentration reproducibility as well as photobleaching effect was also studied. Thirdly, the concentration region of PCR products was postly transferred to the detection window using the electroosmotic flow and detected by laser induced fluorescence (LIF). Finally, the concentration behavior of lambda DNA under lower temperature (below15℃) was noticed and discussed.In the third chapter, the concentration behavior of lambda DNA at the micro-nano interface by making a nano-slit on a fused silica capillary was studied systematically using fluorescence imaging. Firstly, the influences of applied voltage and the concentration of buffer on sample enrichment were studied. Secondly, the concentration factor of lambda DNA with this micro-nano interface was estimated and the maximal concentration factor of105was obtained. Finally, the current change of the total concentration progress was investigated.This work shows that the nanofluidic interfaces established on the fused silica capillary can be well used for high efficient electrokinetic concentration of DNA, with comparable efficiency as PCR amplification.