Department of Chemical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA.
Lab Chip. 2012 Feb 7;12(3):647-51. doi: 10.1039/c2lc20880f. Epub 2011 Dec 16.
Polymer-monovalent salt-induced single-molecule DNA compaction/condensation in a microfluidic stagnation point flow was studied by analyzing both DNA compaction images and time trajectories. For the whole DNA compaction process we observed three successive steps: Step I, a relaxation process of the stretched DNA that occurs slowly along the whole DNA chain, Step II, nucleus formation and growth, and Step III, corresponding to a rapid compaction of the chain. A memory effect was observed between Steps I and III, and a new (intruder-induced) nucleation mode was observed for the first time. This study extends the use of the microfluidic stagnation point flow, which we have previously used for sequence detection and to measure enzyme kinetics site-specifically.
聚合物-单价盐诱导的微流道驻点流中单分子 DNA 的压缩/凝聚通过分析 DNA 压缩图像和时间轨迹进行了研究。对于整个 DNA 压缩过程,我们观察到三个连续的步骤:步骤 I,伸展 DNA 的松弛过程,该过程沿着整个 DNA 链缓慢发生;步骤 II,核的形成和生长;以及步骤 III,对应于链的快速压缩。在步骤 I 和步骤 III 之间观察到记忆效应,并且首次观察到新的(入侵物诱导的)成核模式。这项研究扩展了微流道驻点流的应用,我们之前曾使用该流道进行序列检测,并特异性地测量酶动力学。