Shiga toxin-producing E. coli (STEC) is a food-borne pathogen of great concern due to the severity of the disease it can cause. A key pathogenicity factor is the ability to produce Shiga T Toxin 1 and 2, which are encoded by genes stx. Herein we report the development of a highly sensitive, label-free, electrochemical DNA-based sensor for the detection of the stx1 gene using interdigitated gold microelectrodes (IDEs) on fully integrated silicon chips. Each IDE comprised a working IDE, used for DNA probe immobilisation and an accumulator IDE. The working IDE was modified with gold nanoparticles (Au NPs) and chitosan gold nanocomposite to allow a covalent attachment of amine-modified probe DNA. The electrochemical detection was undertaken using methylene blue (MB) as a redox molecule, which intercalated into the double-strand DNA. The accumulator IDE was used for the electrostatic accumulation of the MB to the DNA binding region of the sensor thereby greatly enhancing sensitivity. The reduction of MB was recorded using square wave voltammetry (SWV). Using this approach, we achieved a linear response between 10⁻¹⁶ and 10⁻⁶ M of synthetic target strand with the lowest measured limit of detection of 100 aM after 20 min of hybridisation time. Subsequently, chromosomal DNA from four different E. coli strains (two stx1 positives and two stx1 negatives), Listeria monocytogenes and Bacillus cereus were used to confirm the selectivity of the presented method. This novel on-chip biosensor for the detection of STEC has the potential to be used for point-of-use detection.

产志贺毒素大肠杆菌(STEC) 是一种食源性病原体，由于它可能引起的疾病严重性而备受关注。一个关键的致病因素是产生志贺 T 毒素 1 和 2 的能力，它们由基因stx编码。在此，我们报告了一种用于检测stx1的高灵敏度、无标记、基于电化学 DNA 的传感器的开发。在完全集成的硅芯片上使用叉指型金微电极 (IDE) 基因。每个 IDE 包括一个用于 DNA 探针固定的工作 IDE 和一个累加器 IDE。工作 IDE 用金纳米粒子 (Au NPs) 和壳聚糖金纳米复合材料进行了修饰，以允许胺修饰的探针 DNA 共价连接。电化学检测使用亚甲蓝 (MB) 作为氧化还原分子，嵌入双链 DNA 中。蓄能器 IDE 用于将 MB 静电积累到传感器的 DNA 结合区域，从而大大提高了灵敏度。使用方波伏安法 (SWV) 记录 MB 的减少。^{使用这种方法，我们实现了 10 -16}和 10 ^-6之间的线性响应 在杂交时间 20 分钟后，合成目标链的 M 具有 100 aM 的最低检测限。随后，来自四种不同大肠杆菌菌株（两个stx1阳性和两个stx1阴性）、单核细胞增生李斯特菌和蜡状芽孢杆菌的染色体 DNA 用于确认所提出方法的选择性。这种用于检测 STEC 的新型片上生物传感器具有用于使用点检测的潜力。