(340c) Tilted Post Arrays for Separating Long DNA
AIChE Annual Meeting
Tuesday, November 18, 2014 - 1:20pm to 1:45pm
Recent simulations by Chen and Dorfman (Electrophoresis 35, 405-411, 2014) suggested that electrophoretic DNA separations in hexagonal arrays of posts would be improved by tilting the electric field with respect to the lattice vectors of the array. This improvement is attributed to the elimination of the channels between the posts that are present in normal post arrays. After the DNA collides with a post and unravels, it can travel in the channel for a substantial distance before it collides again. This effect is stronger at higher electric fields, typically greater than 20 V/cm, and results in the deterioration of separation quality at higher fields. In the tilted post array the DNA collides more often, but the posts are still in a regular array so the probability of multi-post collisions, which can significantly increase dispersion in the chip, is not increased. Overall, this results in a higher resolution separation or allows for the use of shorter post arrays.
We have constructed such an array where the electric field is applied at an angle equidistant between the two lattice vectors. The array leads to (i) baseline resolution of 20 kbp DNA and λ DNA (48.5 kbp) in a 4 mm channel and (ii) separations up to 50 V/cm, both of which are improvements over typical sparse post arrays. The predicted time required to reach a resolution of unity was approximately 5 mins, independent of electric field. The separations are more reproducible at higher fields.