Trammell Scott A, Zabetakis Dan, Moore Martin, Verbarg Jasenka, Stenger David A
Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, United States of America.
PLoS One. 2014 Dec 30;9(12):e115966. doi: 10.1371/journal.pone.0115966. eCollection 2014.
Square wave voltammetry for the reduction of 2,4,6-trinitrotoluene (TNT) was measured in 100 mM potassium phosphate buffer (pH 8) at gold electrodes modified with self-assembled monolayers (SAMs) containing either an alkane thiol or aromatic ring thiol structures. At 15 Hz, the electrochemical sensitivity (µA/ppm) was similar for all SAMs tested. However, at 60 Hz, the SAMs containing aromatic structures had a greater sensitivity than the alkane thiol SAM. In fact, the alkane thiol SAM had a decrease in sensitivity at the higher frequency. When comparing the electrochemical response between simulations and experimental data, a general trend was observed in which most of the SAMs had similar heterogeneous rate constants within experimental error for the reduction of TNT. This most likely describes a rate limiting step for the reduction of TNT. However, in the case of the alkane SAM at higher frequency, the decrease in sensitivity suggests that the rate limiting step in this case may be electron tunneling through the SAM. Our results show that SAMs containing aromatic rings increased the sensitivity for the reduction of TNT when higher frequencies were employed and at the same time suppressed the electrochemical reduction of dissolved oxygen.
在含有烷硫醇或芳香环硫醇结构的自组装单分子层（SAMs）修饰的金电极上，于100 mM磷酸钾缓冲液（pH 8）中测量了用于还原2,4,6-三硝基甲苯（TNT）的方波伏安法。在15 Hz时，所有测试的SAMs的电化学灵敏度（µA/ppm）相似。然而，在60 Hz时，含有芳香结构的SAMs比烷硫醇SAM具有更高的灵敏度。事实上，烷硫醇SAM在较高频率下灵敏度降低。在比较模拟和实验数据之间的电化学响应时，观察到一个总体趋势，即在实验误差范围内，大多数SAMs对于TNT还原具有相似的异质速率常数。这很可能描述了TNT还原的一个速率限制步骤。然而，对于较高频率下的烷烃SAM，灵敏度的降低表明在这种情况下速率限制步骤可能是电子通过SAM的隧穿。我们的结果表明，当采用较高频率时，含有芳香环的SAMs提高了TNT还原的灵敏度，同时抑制了溶解氧的电化学还原。
