Magnetoswitchable electrochemistry gated by alkyl-chain-functionalized magnetic nanoparticles: Control of diffusional and surface-confined electrochemical processes
Magnetoswitchable electrochemistry gated by alkyl-chain-functionalized magnetic nanoparticles: Control of diffusional and surface-confined electrochemical processes
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DOI：
10.1021/ja042910c
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发表时间：
2005-03-23
影响因子：
15
通讯作者：
Willner, I
中科院分区：
文献类型：
--
作者：
Katz, E;Baron, R;Willner, I
由十一烷酸盐覆盖的磁铁矿组成的磁性纳米颗粒（平均直径约为100 μ m）。5 nm）用于选择性地门控扩散和表面限制的电化学反应。两相系统组成的缓冲水溶液和甲苯相，其中包括悬浮的十一烷酸酯封端的磁性纳米粒子被用来控制电极表面的界面性质。两种不同的现象通过借助于外部磁体将磁性纳米颗粒吸引到电极来控制：（i）被吸引的磁性纳米颗粒在电极表面上形成疏水层，导致扩散电化学过程的阻断，同时保留表面限制的电化学单元的氧化还原功能。(ii)对于某些表面固定的氧化还原物质（例如，醌），磁性纳米颗粒对电极表面的吸引将该过程的机理从水性电化学改变为干有机相电化学。此外，在电极处的生物电催化和电催化转化通过磁性纳米颗粒对电极表面的吸引来控制。通过吸引到电极的磁性纳米颗粒来控制修饰电极的催化功能在两个不同的方向上举例说明：（i）使用表面限制的二茂铁单层作为电子转移介体来阻断葡萄糖氧化酶（GOx）对葡萄糖的生物电催化氧化。(ii)过氧化氢异丙苯电催化还原微过氧化物酶-11的活化。在后一种系统中，疏水性磁性纳米颗粒吸附甲苯，并且疏水性基质充当氢过氧化枯烯到用微过氧化物酶-11催化剂改性的电极表面的载体。
Magnetic nanoparticles consisting of undecanoate-capped magnetite (average diameter ca. 5 nm) are used to selectively gate diffusional and surface-confined electrochemical reactions. A two-phase system consisting of an aqueous buffer solution and a toluene phase that includes the suspended undecanoate-capped magnetic nanoparticles is used to control the interfacial properties of the electrode surface. Two different phenomena are controlled by attraction of the magnetic nanoparticles to the electrode by means of an external magnet: (i) The attracted magnetic nanoparticles form a hydrophobic layer on the electrode surface resulting in the blocking of diffusional electrochemical processes, while retaining the redox functions of surface-confined electrochemical units. (ii) For certain surface-immobilized redox species (e.g., quinones), the attraction of the magnetic nanoparticles to the electrode surface alters the mechanism of the process from an aqueous-type electrochemistry to a dry organic-phase-type electrochemistry. Also, bioelectrocatalytic and electrocatalytic transformations at the electrode are controlled by means of attraction of the magnetic nanoparticles to the electrode surface. Controlling the catalytic functions of the modified electrode by means of the magnetic nanoparticles attracted to the electrode is exemplified in two different directions: (i) Blocking of the bioelectrocatalyzed oxidation of glucose by glucose oxidase (GOx) using a surface-confined ferrocene monolayer as electron-transfer mediator. (ii) Activation of the microperoxidase-11 electrocatalyzed reduction of cumene hydroperoxide. In the latter system, the hydrophobic magnetic nanoparticles adsorb toluene, and the hydrophobic matrix acts as a carrier for cumene hydroperoxide to the electrode surface modified with the microperoxidase-11 catalyst.