Exploring the Motional Dynamics of End-Grafted DNA Oligonucleotides by in Situ Electrochemical Atomic Force Microscopy

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• 作者：Kang Wang ; Cé ; dric Goyer ; Agn&egrave ; s Anne ; Christophe Demaille
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：May 31, 2007
• 年：2007
• 卷：111
• 期：21
• 页码：6051 - 6058
• 全文大小：249K
• 年卷期：v.111,no.21(May 31, 2007)
• ISSN：1520-5207

文摘

We introduce herein the use of atomic-force electrochemical microscopy (AFM-SECM) to simultaneouslyprobe locally the conformation and motional dynamics of nanometer-sized single-stranded (ss) and double-stranded (ds) DNA oligonucleotides end-tethered to electrode surfaces. The ss-DNA system studied hereconsists of a low-density monolayer of (dT)₂₀ oligonucleotides, 5'-thiol end-tethered onto a flat gold surfacevia a C₆ alkyl linker and bearing at their free 3'-end a redox ferrocene label. It is shown that, as a result ofthe flexibility of the relatively long C₆ linker, hinge motion, rather than elastic deformation of the DNAchain, is the major component of the dynamics of both the (dT)₂₀ strand and its post-hybridized (dT-dA)₂₀duplex. DNA chain elasticity is nevertheless sufficiently contributing to the overall dynamics to result in ~4times slower dynamics for (dT-dA)₂₀ than for (dT)₂₀. Taking advantage of this dissimilar dynamical behaviorof ss- and ds-DNA, it is demonstrated that hybridization can be easily locally detected at the scale of ~200molecules by AFM-SECM.