Han Jinli, Zhang Ting, Zhou Xiaochun
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
Division of Advanced Nanomaterials, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences (CAS), Suzhou 215123, China.
Chem Biomed Imaging. 2023 Mar 13;1(2):140-146. doi: 10.1021/cbmi.3c00010. eCollection 2023 May 22.
Herein, single DNA molecule stretching in a hydrodynamic flow was monitored by total internal reflection fluorescence microscopy (TIRFM). Different driving forces for DNA stretching were assessed systematically. The binding force between the substrate and the DNA molecule significantly affected the dynamic stretching behavior of coiled DNA, where DNA stretched only on the substrate modified by -NH due to electrostatic adsorption. Proper flow force from the fluid was favorable for DNA stretching, which was in stark contrast to DNA stretching restricting at a lower flow rate or washing off DNA molecules at a higher flow rate of fluid. Moreover, DNA stretching was restricted in low pH solution but improved in high pH solution. This is due to the confrontation between contractive and repulsion forces in coiled DNA molecules in different pH, which is related to the Donnan equilibrium in a single condensed DNA molecule. Additionally, external Na would break this Donnan equilibrium, leading to a restriction for DNA stretching. This study will guide quantitative dynamics studies of DNA stretching in the future.
在此，通过全内反射荧光显微镜（TIRFM）监测了在流体动力学流动中单个DNA分子的拉伸。系统地评估了DNA拉伸的不同驱动力。底物与DNA分子之间的结合力显著影响了盘绕DNA的动态拉伸行为，其中由于静电吸附，DNA仅在经-NH修饰的底物上拉伸。来自流体的适当流体力有利于DNA拉伸，这与在较低流速下限制DNA拉伸或在较高流体流速下冲走DNA分子形成鲜明对比。此外，DNA拉伸在低pH溶液中受到限制，但在高pH溶液中得到改善。这是由于不同pH条件下盘绕DNA分子中收缩力和排斥力之间的对抗，这与单个浓缩DNA分子中的唐南平衡有关。此外，外部Na会打破这种唐南平衡，导致DNA拉伸受到限制。该研究将为未来DNA拉伸的定量动力学研究提供指导。
