Microbial safety of drinking water constitutes a major concern in countries at all levels of economic development. Thus, rapid, sensitive and cost effective methods of pathogenic bacteria detection, like common Escherichia coli O157:H7, which can cause important diseases, are highly required.

In this work an impedimetric transducer modified with E. coli specific aptamer is studied. To enhance the sensitivity a three-dimensional interdigitated electrode array (3D-IDEA) impedimetric transducer, in which the electrodes are separated by insulating barriers was used. In this sensor chemical reactions at the surface of the barrier provoke electrical charge redistribution which causes changes in the surface conductivity. A DNA aptamer, which recognizes specifically the outer membrane proteins of the E. coli O157:H7, was selected as the biorecognition moiety.

Here we report a novel label-free impedimetric aptasensor for detection and quantification of pathogenic E. coli O157:H7 with a low detection limit, good selectivity and short detection time. The developed sensor shows a linear response (R² = 0.977), proportional to the logarithm of bacterial concentration present in the sample, with the limit of detection (LOD) of about 10² cfu mL⁻¹. No response of the aptasensor was registered in the presence of other bacterial strains (E. coli k12, Salmonella typhimurium, Staphylococcus aureus), which confirms the selectivity of the suggested detection method. Additionally, the methodology of the aptasensor regeneration was developed, so that the detection may be performed several times with the same sensor. Moreover, suitability of the aptasensor for bacteria detection in real samples was demonstrated with a new approach involving bacteria pre-concentration.

饮用水的微生物安全性是各个经济发展水平国家的主要关注点。因此，迫切需要快速，灵敏且经济高效的病原菌检测方法，例如可以引起重要疾病的普通大肠杆菌O157：H7。

在这项工作中，研究了用大肠杆菌特异性适体修饰的阻抗传感器。为了提高灵敏度，使用了三维叉指式电极阵列（3D-IDEA）阻抗传感器，其中电极由绝缘势垒隔开。在该传感器中，势垒表面的化学反应会引起电荷重新分布，从而导致表面电导率发生变化。选择能特异性识别大肠杆菌O157：H7外膜蛋白的DNA适体作为生物识别部分。

在这里，我们报告了一种新颖的无标记阻抗适体传感器，用于检测和定量病原大肠杆菌O157：H7，具有低检测限，良好的选择性和较短的检测时间。开发的传感器显示线性响应（R ²  = 0.977），与样品中细菌浓度的对数成正比，检测极限（LOD）约为10 ²  cfu mL ^-1。在其他细菌菌株（大肠杆菌k12，鼠伤寒沙门氏菌，金黄色葡萄球菌）的存在下，aptasensor没有反应，这证实了建议的检测方法的选择性。另外，开发了适体传感器再生的方法，以便可以使用同一传感器执行多次检测。而且，通过涉及细菌预浓缩的新方法证明了适体传感器在实际样品中检测细菌的适用性。