Impact of Surface Chemistry on Nanoparticle-Electrode Interactions in the Electrochemical Detection of Nanoparticle Collisions
Impact of Surface Chemistry on Nanoparticle-Electrode Interactions in the Electrochemical Detection of Nanoparticle Collisions
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DOI：
10.1021/acs.langmuir.5b03033
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发表时间：
2015-11-03
期刊：
影响因子：
3.9
通讯作者：
Unwin, Patrick R.
中科院分区：
文献类型：
--
作者：
Chen, Chang-Hui;Rayenhill, Emma R.;Unwin, Patrick R.
在支撑电极上对单个纳米粒子（NP）进行电化学检测，可以提供纳米级表面化学和基本电子转移（ET）性质的关键信息。本研究采用扫描电化学电池显微镜（SECCM）作为流体装置，递送单个柠檬酸盐覆盖的金纳米粒子（AuNPs），并研究它们与一系列具有不同末端基团（-COOH、-OH和-CH3）的烷硫醇修饰金电极之间的相互作用。通过aunp介导的Fe(CN)(6)(4-/3-) ET反应在水溶液中检测到单NP碰撞。烷烃硫醇末端基团对aunp的碰撞频率、停留时间和电流时间特性有很大影响。概述了确定这些参数的方法，包括仪器响应函数的影响，以及推导ET动力学。为了进一步了解AuNP与这些表面的相互作用，原子力显微镜（AFM）力测量使用柠檬酸盐修饰的Au涂层AFM尖端和相同的烷硫醇修饰的Au底物在水溶液中以与AuNP碰撞实验相同的潜在偏压进行。在oh端表面上的力曲线显示无斥力和可忽略的附着力。相反，在COOH端表面上可以观察到明显的斥力（接近时），在COOH-和ch3端表面上都可以观察到粘附力（收缩时）。这些相互作用有助于解释AuNP碰撞中的停留时间和碰撞频率。更一般地说，由于AFM探测到的界面性质在NP碰撞实验中被放大，并且新的特征也变得明显，这表明这些实验提供了一种在纳米尺度上探测表面化学的新手段。
The electrochemical detection of a single nanoparticle (NP) at a support electrode can provide key information on surface chemistry and fundamental electron transfer (ET) properties at the nanoscale. This study employs scanning electrochemical cell microscopy (SECCM) as a fluidic device to both deliver individual citrate-capped gold nanopartides (AuNPs) and study the interactions between them and a range of alkanethiol-modified Au electrodes with different terminal groups, namely, -COOH, -OH, and -CH3. Single NP collisions were detected through the AuNP-mediated ET reaction of Fe(CN)(6)(4-/3-) in aqueous solution. The collision frequency, residence time, and current-time characteristics of AuNPs are greatly affected by the terminal groups of the alkanethiol. Methods to determine these parameters, including the effect of the instrument response function, and derive ET kinetics are outlined. To further understand the interactions of AuNPs with these surfaces, atomic force microscopy (AFM) force measurements were performed using citrate-modified Au-coated AFM tips and the same alkanethiol-modified Au substrates in aqueous solution at the same potential bias as for the AuNP collision experiments. Force curves on OH-terminated surfaces showed no repulsion and negligible adhesion force. In contrast, a clear repulsion (on approach) was seen for COOH-terminated surface and adhesion forces (on retract) were observed for both COOH- and CH3-terminated surfaces. These interactions help to explain the residence times and collision frequencies in AuNP collisions. More generally, as the interfacial properties probed by AFM appear to be amplified in NP collision experiments, and new features also become evident, it is suggested that such experiments provide a new means of probing surface chemistry at the nanoscale.