Chen Zhen, Dorfman Kevin D
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA.
Electrophoresis. 2014 Feb;35(2-3):405-11. doi: 10.1002/elps.201300191. Epub 2013 Sep 14.
Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such "tilted" post arrays is superior to the standard "un-tilted" approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low-electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the "free path," i.e. the average distance of ballistic trajectories of point-sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device.
通过布朗动力学模拟，我们表明，当施加的电场矢量与微米级柱体六边形阵列的晶格矢量不一致时，DNA在该阵列中的电泳会发生质的变化。在这种“倾斜”柱体阵列中的DNA电泳优于标准的“未倾斜”方法；虽然在低电场强度下，在倾斜柱体阵列中实现单位分辨率所需的时间与未倾斜阵列相似，但该时间（i）在倾斜阵列中随电场强度呈指数下降，（ii）在未倾斜阵列中随电场强度呈指数增加。尽管柱体阵列中的DNA动力学很复杂，但电泳迁移率结果表明，“自由路径”，即从晶胞中随机位置发射的点状粒子的弹道轨迹的平均距离，直到它们与下一个柱体相交，是详细DNA轨迹的一个有用代理。对自由路径的分析揭示了介质各向异性与其中DNA传输之间的基本联系，这不仅仅是简单地改进分离装置。
