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Improved DNA straightening and attachment via optimal Mg2+ ionic bonding under electric field for AFM imaging in liquid phase

Liu, Ziyu, Xu, Hongmei, Wang, Ying, Yang, Fan, Yin, Yaoting, Zhang, Sheng, Weng, Zhankun, Song, Zhengxun, Wang, Zuobin
Micron 2019 v.124 pp. 102678
DNA, adhesion, atomic force microscopy, electric field, gene editing, gene targeting, image analysis, liquids, magnesium, mica
In this research, a novel method is proposed to improve DNA straightening under an applied electric field to facilitate imaging in a liquid phase by modifying the substrate with varying Mg2+ ion concentrations. A two-dimensional network of DNA structures was successfully stretched on Mg2+-modified mica substrates under a DC electric field (1 V, 1 A) and imaged in gaseous and aqueous phases by atomic force microscopy. The results revealed that an optimum concentration of Mg2+ ion (4.17 μmol/ml) allowed DNA straightening under an electric field, thus facilitating its imaging in the liquid phase. Furthermore, DNA adhesion under different concentrations of Mg2+ was measured and a maximum adhesion force of 76.19 pN was achieved. This vital work has great potential in gene knockout and targeted gene editing.