Characterization and Application of Controllable Local Chemical Changes Produced by Reagent Delivery from a Nanopipet

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• 作者：Joe D. Piper ; Chao Li ; Chien-Jung Lo ; Richard Berry ; Yuri Korchev ; Liming Ying ; David Klenerman
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：August 6, 2008
• 年：2008
• 卷：130
• 期：31
• 页码：10386-10393
• 全文大小：409K
• 年卷期：v.130,no.31(August 6, 2008)
• ISSN：1520-5126

文摘

We introduce a versatile method that allows local and repeatable delivery (or depletion) of any water-soluble reagent from a nanopipet in ionic solution to make localized controlled changes in reagent concentration at a surface. In this work, Na⁺ or OH⁻ ions were dosed from the pipet using pulsed voltage-driven delivery. Total internal reflection fluorescence from CoroNa Green dye in the bath for Na⁺ ions or fluorescein in the bath for pH quantified the resulting changes in local surface concentration. These changes had a time response as short as 10 ms and a radius of 1−30 μm and depended on the diameter of the pipet used, the applied voltage, and the pipet−surface separation. After the pipet dosing was characterized in detail, two proof-of-concept experiments on single cells and single molecules were then performed. We demonstrated local control of the sodium-sensitive flagellar motor in single Escherichia coli chimera on the time scale of 1 s by dosing sodium and monitoring the rotation of a 1 μm diameter bead fixed to the flagellum. We also demonstrated triggered single-molecule unfolding by dosing acid from the pipet to locally melt individual molecules of duplex DNA, as observed using fluorescent resonance energy transfer.