Abstract
The device with nano-channel matrices was fabricated and used to sieve DNA molecules. Channel matrices, which had been fabricated with the widths of individual nano-channel were 50, 200, and 450 nano-meters. The interval between two adjacent rows of nano-channels varies from 1 μm to 3 μm. Three different kinds of DNA molecules including Plasmid-2.8 kbps (~1 μm), λ-48.5 kbps (~16 μm) and T4-166 kbps (~55 μm) were used in these experiments. It was found that the mobility of shorter DNA molecules were not always greater than that of longer ones. Overall, we could divide the results into three parts. (1) In the width 50 nm channel matrices, the result of this is like the result of gel electrophoresis, which showed the mobility decreased monotonically with the length of DNA molecules. (2) In the width 200 nm channel matrices, the entropic trapping dominated, longer molecules have a higher probability to escape trapping regions due to high successful attacking frequency with the larger contact area, so the mobility increased monotonically with the length of DNA molecules and the result is reverse to the aforementioned result. (3) As different lengths of DNA molecules sieved in the width 450 nm channel matrices, the Ogston mechanism dominated, molecules could pass through the nanochannel without great deformation so the mobility decreased monotonically with the length of DNA molecules. Besides these results, compared with regular micro- and nano-trenches of previous authors' works, DNA molecules electrophoresis in these trenches was just one direction confined, but the motion of DNA molecules was confined in both directions perpendicular to the direction of drift of DNA molecules in our chip. Compared with time-consuming (1~24 hrs) and large sample consumption of conventional methods, gel DNA electrophoresis and Pulsed field gel electrophoresis, DNA molecules could be separated in 10 minutes and low sample consumption by this technique. Thus, this work not only provides a more helpful method for understanding separation processes in gel DNA electrophoresis, but also provides a more efficient method to sieve different lengths of DNA molecules.