Escherichia coli O157:H7 is an extremely serious foodborne pathogen accounting for a vast number of hospitalizations. In this system, a simple, rapid, and safe compound method was developed based on carbonyl iron powder (CIP) and multiwalled carbon nanotubes (MWCNT). Then, the CIP@MWCNT-based aptasensor was constructed by strong π-stacking between nanocomposite and aptamer, single-strand DNA, causing fluorescent quenching of the dye-labeled aptamer. The restoration of dye fluorescence could be achieved when aptamer came off the surface of the CIP@MWCNT nanocomposite due to the presence of target bacteria. To the best of our knowledge, this fabrication of magnetic carbon nanotubes without irritating and corrosive reagents is described for the first time. The sensing platform was also an improvement on the conventional formation of the aptasensor between carbon materials and DNA aptamer. The nanocomposite was verified by diverse characterization of zeta potential, Fourier-transform infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray analysis. The CIP@MWCNT-based aptasensor was an effective nanoplatform for quantitative detection of E. coli O157:H7, and was measured to have high specificity, good reproducibility, and strong stability. The aptasensor's capacity to quantify E. coli O157:H7 was as low as 7.15 × 10³ cfu/mL in pure culture. The detection limit of E. coli O157:H7 was 3.15 × 10² cfu/mL in contaminated milk after 1 h of pre-incubation. Hence, the developed assay is a new possibility for effective synthesis of nanocomposites and sensitive tests of foodborne pathogens in the dairy industry.

大肠杆菌O157：H7是一种极为严重的食源性病原体，占大量住院治疗。在该系统中，开发了一种基于羰基铁粉（CIP）和多壁碳纳米管（MWCNT）的简单，快速且安全的复合方法。然后，通过在纳米复合材料与适体，单链DNA之间形成强π堆积来构建基于CIP @ MWCNT的适体传感器，从而使染料标记的适体发生荧光猝灭。当适体由于目标细菌的存在而脱离CIP @ MWCNT纳米复合材料的表面时，可以实现染料荧光的恢复。据我们所知，首次没有磁性和刺激性试剂的磁性碳纳米管的制造。传感平台也是对碳材料和DNA适体之间的适体传感器常规形成的改进。纳米复合材料通过zeta电位的多种表征，傅立叶变换红外光谱，透射电子显微镜和能量色散X射线分析得到了验证。基于CIP @ MWCNT的适体传感器是一种有效的纳米平台，可用于定量检测大肠杆菌O157：H7，经测定具有很高的特异性，良好的再现性和较强的稳定性。在纯培养物中，适体传感器定量大肠杆菌O157：H7的能力低至7.15×10 ³ cfu / mL。预孵育1小时后，在受污染的牛奶中，大肠杆菌O157：H7的检出限为3.15×10 ² cfu / mL。因此，开发的测定方法为有效合成纳米复合材料和对乳业中食源性病原体进行敏感检测提供了新的可能性。