Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States.
Langmuir. 2011 Jun 7;27(11):6768-79. doi: 10.1021/la105128q. Epub 2011 May 2.
A 2-D molecularly imprinted monolayer (2-D MIM) approach was used to prepare a simple and robust sensor for nitroaromatic compounds with 2,4-dinitrotoluene (DNT) as the model compound, which is a precursor and analog for explosive 2,4,6-trinitrotoluene (TNT). In contrast to studies utilizing long-chain hexadecylmercaptan self-assembled monolayers (SAM)s for sensing, a shorter-chain alkylthiol (i.e., butanethiol SAM) was utilized for DNT detection. The role of the chain length of the coadsorbed alkylthiol was emphasized with a matched template during solution adsorption. Semiempirical PM3 quantum calculations were used to determine the molecular conformation and complexation of the adsorbates. A switching mechanism was invoked on the basis of the ability of the template analyte to alter the packing arrangement of the alkylthiol SAMs near defect sites as influenced by the DNT-ethanol solvent complex. A 2-D MIM was formed on the Au surface electrode of a quartz crystal microbalance (QCM), which was then used to sense various concentrations of the analyte. Interestingly, the 2-D MIM QCM also enabled the selective detection of DNT even in a mixed solution of competing molecules, demonstrating the selectivity figure of merit. Likewise, electrochemical impedance spectroscopy (EIS) data at different concentrations of DNT confirmed the 2-D MIM effectiveness for sensing based on the interfacial conformation and electron-transport properties of the imprinted butanethiol SAM.
采用二维分子印迹单层（2-D MIM）方法，以 2,4-二硝基甲苯（DNT）为模型化合物，制备了一种简单而强大的用于检测硝基芳香族化合物的传感器，DNT 是爆炸物 2,4,6-三硝基甲苯（TNT）的前体和类似物。与利用长链十六烷基硫醇自组装单层（SAM）进行传感的研究不同，在检测 DNT 时使用了更短链的烷基硫醇（即丁硫醇 SAM）。通过在溶液吸附过程中使用匹配的模板强调了共吸附烷基硫醇链长的作用。采用半经验 PM3 量子计算来确定吸附物的分子构象和络合。基于模板分析物改变缺陷部位附近烷基硫醇 SAM 组装排列的能力，提出了一种开关机制，这种能力受 DNT-乙醇溶剂络合物的影响。在石英晶体微天平（QCM）的金表面电极上形成 2-D MIM，然后用于感应各种浓度的分析物。有趣的是，2-D MIM QCM 甚至可以在竞争分子的混合溶液中选择性地检测 DNT，显示出了选择性的优劣。同样，不同浓度的 DNT 的电化学阻抗谱（EIS）数据证实了基于印迹丁硫醇 SAM 的界面构象和电子传输特性的 2-D MIM 用于传感的有效性。
