Curtin Institute for Functional Molecules and Interfaces, School of Molecular and Life Sciences , Curtin University , GPO Box U1987, Perth , Western Australia 6845 , Australia.
Anal Chem. 2018 Jul 17;90(14):8470-8477. doi: 10.1021/acs.analchem.8b01172. Epub 2018 Jun 26.
The electrochemical behavior of a synthetic oligonucleotide, thrombin-binding aptamer (TBA, 15-mer), was explored at a liquid-organogel microinterface array. TBA did not display any response when only background electrolytes were present in both phases. On the basis of literature reports that surfactants can influence nucleic acid detection, the response in the presence of cetyltrimethylammonium (CTA) was examined. With both TBA and CTA in the aqueous phase, the transfer current for CTA was diminished, signifying the interaction of CTA with TBA. Experiments with CTA spiked into the organic phase revealed a sharp current peak, consistent with the interfacial formation of a CTA-TBA complex. However, use of CTA as the organic phase electrolyte cation, as the salt with tetrakis(4-chlorophenyl)borate, greatly improved the response to TBA. In this case, a distinctive peak response (at ca. -0.25 V) was attributed to the transfer of CTA across the soft interface to complex with aqueous phase TBA. Employing this process as a detection step enabled a detection limit of 0.11 μM TBA (by cyclic voltammetry). Furthermore, the presence of magnesium cations at physiological concentration resulted in the disappearance of the TBA response because of Mg-induced folding of TBA. Also, the current response of TBA was decreased by the addition of thrombin, indicating TBA interacted with this binding partner. Finally, the interfacial surfactant-aptamer interaction was explored in a synthetic urine matrix that afforded a detection limit of 0.29 μM TBA. These results suggest that aptamer-binding interactions can be monitored by electrochemistry at aqueous-organic interfaces and open up a new possibility for detection in aptamer-binding assays.
在液体-有机凝胶微界面阵列中探索了合成寡核苷酸、凝血酶结合适体（TBA，15 个碱基）的电化学行为。当两相中仅存在背景电解质时，TBA 没有任何响应。根据文献报道，表面活性剂可以影响核酸检测，因此检查了存在十六烷基三甲基溴化铵（CTA）时的响应。在水相中有 TBA 和 CTA 的情况下，CTA 的转移电流减小，表明 CTA 与 TBA 相互作用。在有机相中加入 CTA 的实验显示出尖锐的电流峰，与界面上形成 CTA-TBA 复合物一致。然而，使用 CTA 作为有机相电解质阳离子，作为与四（4-氯苯基）硼酸盐的盐，大大提高了对 TBA 的响应。在这种情况下，独特的峰响应（约 -0.25 V）归因于 CTA 通过软界面转移以与水相 TBA 络合。将此过程用作检测步骤，可实现 0.11 μM TBA 的检测限（通过循环伏安法）。此外，由于 TBA 诱导折叠，生理浓度的镁阳离子的存在导致 TBA 响应消失。此外，凝血酶的加入降低了 TBA 的电流响应，表明 TBA 与该结合配偶体相互作用。最后，在合成尿液基质中探索了界面表面活性剂-适体相互作用，可实现 0.29 μM TBA 的检测限。这些结果表明，可以通过电化学在水-有机界面监测适体结合相互作用，并为适体结合分析中的检测开辟了新的可能性。
