In this study, carbon screen-printed electrodes (SPEs) modified with gold nanoparticles (AuNPs), were prepared for label-free detection of Escherichia coli(E. coli) O157. AuNPs were synthesized by an electrochemical method and then modified on the carbon SPEs to improve the stability and effectiveness of the biosensor. Anti-E. coli O157 antibody was immobilized on the modified SPEs via -NHS cross-linking. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were selected to investigate electrochemical properties of modified carbon SPEs in a 5.0 mM K₃[Fe(CN)₆]/ K₄[Fe(CN)₆] added with 0.1 M KCl as well as to detect E. coli O157 bacteria. Results showed that the carbon SPEs were successfully modified with AuNPs of 18.0 ± 1.6 nm. The electrochemical signal of modified SPEs was stable after CV cycles, and the charge transfer resistance (R_ct) decreased approximately to half of its initial value. Importantly, electrochemical biosensors based on AuNPs-modified carbon SPEs could detect E. coli O157 in the range of 10–10⁶ CFU/mL without labels. The limit of detection was found at 15 CFU/mL with a signal-to-noise ratio of 3:1, and the time of detection was about 30 min. The success of as-prepared biosensor could open a strategy of portable diagnostics for label-free and quick detection of bacterial pathogens causing food-borne diseases, hospital-acquired infections as well as the emerging and re-emerging infectious diseases.

在这项研究中，准备了用金纳米颗粒（AuNPs）修饰的碳丝网印刷电极（SPE），用于无标签检测大肠杆菌（ O. coli） O157。通过电化学方法合成AuNPs，然后在碳SPEs上修饰AuNPs，以提高生物传感器的稳定性和有效性。通过-NHS交联将抗大肠杆菌O157抗体固定在修饰的SPE上。选择循环伏安法（CV）和电化学阻抗谱（EIS）来研究改性碳SPE在添加了0.1 M KCl的5.0 mM K ₃ [Fe（CN）₆ ] / K ₄ [Fe（CN）₆ ]中的电化学性能以及检测大肠杆菌O157细菌。结果表明，碳固相萃取成功地被18.0±1.6 nm的AuNPs修饰。改性SPE的电化学信号在CV循环后保持稳定，并且电荷转移电阻（R _ct）降低至其初始值的一半。重要的是，基于AuNPs修饰的碳SPE的电化学生物传感器可以检测10-10 ⁶范围内的大肠杆菌O157CFU / mL，无标签。检测限为15 CFU / mL，信噪比为3：1，检测时间约为30分钟。如此制备的生物传感器的成功开发，将开启一种便携式诊断的战略，从而无需标签即可快速检测导致食源性疾病，医院获得性感染以及正在出现和重新出现的传染病的细菌病原体。