A pH-Tunable Nanofluidic Diode: Electrochemical Rectification in a Reconstituted Single Ion Channel

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• 作者：Antonio Alcaraz ; Patricio Ramí ; rez ; Elena Garcí ; a-Gimé ; nez ; M. Lidó ; n Ló ; pez ; Andreu Andrio ; Vicente M. Aguilella
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：October 26, 2006
• 年：2006
• 卷：110
• 期：42
• 页码：21205 - 21209
• 全文大小：372K
• 年卷期：v.110,no.42(October 26, 2006)
• ISSN：1520-5207

文摘

We report pH-dependent electrochemical rectification in a protein ion channel (the bacterial porin OmpF)reconstituted on a planar phospholipid membrane. The measurements performed at single-channel level showthat the electric current is controlled by the protein fixed charge and it can be tuned by adjusting the localpH. Under highly asymmetric pH conditions, the channel behaves like a liquid diode. Unlike other nanofluidicdevices that display also asymmetric conductance, here the microscopic charge distribution of the system canbe explored by using the available high-resolution (2.4 Å) channel crystallographic structure. Continuumelectrostatics calculations confirm the hypothesized bipolar structure of the system. The selective titration ofthe channel residues is identified as the underlying physicochemical mechanism responsible for currentrectification.