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Fabrication of two-weir structure-based packed columns for on-chip solid-phase extraction of DNA

Zhong, Runtao, Liu, Dayu, Yu, Linfen, Ye, Nannan, Dai, Zhongpeng, Qin, Jianhua, Lin, Bingcheng
Electrophoresis 2007 v.28 no.16 pp. 2920-2926
DNA, blood, electrophoresis, glass, hepatoma, humans, packing material, paraffin wax, solid phase extraction
Microchip-based packed column SPE of DNA was performed using the microfabricated two-weir structure within a microchannel. We developed two methods to fabricate the two-weir structured glass chips: a "two-side etching/alignment" method and a simplified "one-side/two-step etching" method. The former method required a straightforward alignment step, while the latter approach comprised a simplified wet etching process using paraffin wax as the temporary protective layer. Both methods were convenient and rapid as compared to the previous approaches. Through a reversibly sealed bead-introduction channel, beads can be fed into or out of the chip columns, thus enabling refreshment of the packing materials. Using the proposed chip columns, highly efficient λ-DNA extractions (average recovery >80%) were performed with good chip-to-chip reproducibility (RSD <10%). The on-chip SPE procedure was completed within 15 min at the flow rate of 3 μL/min and the bulk of the loaded DNA was eluted within a small volume of ~8 μL. Application of the microchip-based packed columns was demonstrated by purifying PCR-amplifiable genomic DNA from human hepatocellular carcinoma (HepG2) cells and human whole blood samples.