Antibody fragments for detection of 3‐phenoxybenzoic acid (3‐PBA) are created by disulfide bond cleavage with tris(2‐carboxyethyl)phosphine (TCEP). These antibody fragments are employed to improve the sensitivity for 3‐PBA detection by electrochemical impedance spectroscopy (EIS). The sensitivity and detection limit are compared for biomolecular recognition by both polyclonal antibodies and antibody fragments immobilized through amide bond formation atop a self‐assembled monolayer (SAM) on an Au electrode, as well as antibody fragments directly attached to Au through Au−S covalent bond formation. The detection limit for 3‐PBA is dramatically improved (1.1×10⁻⁸ M) for direct immobilization of antibody fragments through Au−S covalent bond formation relative to immobilization of either polyclonal antibodies (2.1×10⁻⁵ M) or antibody fragments (1.7×10⁻⁵ M) through amide bond formation. This can be attributed primarily to the much lower charge transfer resistance (R_ct) and higher ionic permeability obtained at biosensor interfaces that do not include an Au‐thiol SAM, allowing easier detection of further changes in R_ct. In addition, the exponential dependence of the electron tunnelling rate on biomolecular film thickness increases the sensitivity of the antibody fragments modestly relative to polyclonal antibodies. This is the first quantitative comparison of the use of antibodies and antibody fragments for biomolecular recognition within impedance biosensors.

中文翻译：

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3-苯氧苯甲酸比较整体抗体和抗体片段的生物分子识别的阻抗检测。

用于检测3-苯氧基苯甲酸（3-PBA）的抗体片段是通过用三（2-羧乙基）膦（TCEP）进行二硫键裂解而产生的。这些抗体片段可用于通过电化学阻抗谱（EIS）来提高3-PBA检测的灵敏度。比较了多克隆抗体和通过酰胺键形成的固定在Au电极上自组装单分子层（SAM）上的酰胺键固定的抗体片段以及通过Au-S共价键直接附着到Au的抗体片段对生物分子识别的敏感性和检测极限键的形成。3-PBA的检出限得到了显着提高（1.1×10 ^-8 M）用于通过Au-S共价键形成直接固定抗体片段，相对于 通过酰胺键形成固定多克隆抗体（2.1×10 ^-5  M）或抗体片段（1.7×10 ^-5 M）。这主要归因于在不包含金硫醇SAM的生物传感器界面上获得的低得多的电荷转移电阻（R _ct）和更高的离子渗透性，这使得更容易检测到R _ct的进一步变化。另外，电子隧穿速率对生物分子膜厚度的指数依赖性增加了抗体片段相对于多克隆抗体的敏感性。这是在阻抗生物传感器内使用抗体和抗体片段进行生物分子识别的首次定量比较。