In this paper, we provide an in-depth electrochemical characterization of a label-free impedimetric immunosensor for rapid detection of ochratoxin A. The sensor was based on a carbodiimide-mediated amide coupling reaction to immobilize a specific ochratoxin A antibody onto 4-mercaptobenzoic acid-modified commercial screen-printed gold electrode. Different variables affecting the performance of the developed sensor were optimized. Cyclic voltammetry and electrochemical impedance spectroscopy were used to analyse modifications of the interfacial properties occurring at each step of the biosensor assembly. The free electrode surface area, the diffusion coefficient, the peak-to-peak separation, the heterogeneous electron transfer constant, and charge transfer resistance have been calculated and compared. The decrease of charge transfer resistance values was linearly proportional to the ochratoxin A concentration in the range of 0.37– 2.86 ng/mL, with a detection limit of 0.19 ng/mL, a limit of quantification of 0.40 ng/mL, very good selectivity, reproducibility, and storage stability in the absence of antifouling agents. Surface morphology and topographic data at each step of the immunosensor assembly were studied by Atomic Force Microscopy, which also provided information on the specific binding of ochratoxin A. Finally, contact angle measurements revealed the hydrophilicity evolution of the surface during sensor assembly enabling OTA binding.

在本文中，我们提供了一种用于快速检测赭曲霉毒素 A 的无标记阻抗免疫传感器的深入电化学表征。该传感器基于碳二亚胺介导的酰胺偶联反应，将特定的赭曲霉毒素 A 抗体固定在 4-巯基苯甲酸上-改进的商业丝网印刷金电极。对影响所开发传感器性能的不同变量进行了优化。循环伏安法和电化学阻抗谱用于分析在生物传感器组装的每个步骤中发生的界面特性的变化。计算并比较了自由电极表面积、扩散系数、峰峰值分离、异质电子转移常数和电荷转移电阻。电荷转移电阻值的降低与赭曲霉毒素 A 浓度成线性比例，范围为 0.37-2.86 ng/mL，检测限为 0.19 ng/mL，定量限为 0.40 ng/mL，选择性非常好，在没有防污剂的情况下，重现性和储存稳定性。通过原子力显微镜研究免疫传感器组装每个步骤的表面形态和形貌数据，这也提供了赭曲霉毒素 A 特异性结合的信息。最后，接触角测量揭示了传感器组装过程中表面的亲水性演变，使 OTA 结合成为可能。在没有防污剂的情况下，重现性和储存稳定性。通过原子力显微镜研究免疫传感器组装每个步骤的表面形态和形貌数据，这也提供了赭曲霉毒素 A 特异性结合的信息。最后，接触角测量揭示了传感器组装过程中表面的亲水性演变，使 OTA 结合成为可能。在没有防污剂的情况下，重现性和储存稳定性。通过原子力显微镜研究免疫传感器组装每一步的表面形态和形貌数据，这也提供了赭曲霉毒素 A 特异性结合的信息。最后，接触角测量揭示了传感器组装过程中表面的亲水性演变，从而实现了 OTA 结合。