An electrochemical immunosensor for Vibrio cholerae toxin (VCT) has been developed using electrospun carbon nanofibers (CNFs) as the electrode platform. To fabricate the immunosensor, the anti-cholera toxin antibody (Ab) was covalently immobilized on the electrode platforms using the carbodiimide chemistry for the amide bond formation. Every step of the formation of the immunosensor and the subsequent binding of the VCT subunit antigen (Ag) was electrochemically interrogated. The immunosensor gave excellent reproducibility and sensitivities: limits of detection (ca. 1.2 × 10^–13 g mL^–1), limits of quantification (ca. 1.3 × 10^–13 g mL^–1), and a wide linear range for the anti-cholera detection of 8 orders of magnitude (10^–13 to 10^–5 g mL^–1). One of the key findings was the enhanced sensitivity of the VCT detection using aged rather than the freshly prepared redox probe, described here as Redox Probe Aging-Induced Sensitivity Enhancement (“Redox-PrAISE”). The Redox-PrAISE was found more useful in the real application of these immunosensors, showing comparable or even better sensitivity for eight real cholera-infested water samples than the conventional clinical culture method. This immunosensor shows promise for the potential development of point-of-care diagnosis of VCT. Importantly, this study highlights the importance of considering the nature of the redox probe on the electrochemical sensing conditions when designing impedimetric immunosensors.

中文翻译：

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静电纺丝碳纳米纤维作为霍乱弧菌毒素的电化学免疫传感平台：氧化还原探针的老化作用

使用电纺碳纳米纤维（CNF）作为电极平台，开发了霍乱弧菌毒素（VCT）电化学免疫传感器。为了制造免疫传感器，使用碳二亚胺化学方法将抗霍乱毒素抗体（Ab）共价固定在电极平台上以形成酰胺键。电化学检测免疫传感器形成的每个步骤以及随后的VCT亚基抗原（Ag）的结合。免疫传感器具有出色的重现性和敏感性：检测限（约1.2×10 ^–13 g mL ^–1），定量限（约1.3×10 ^–13 g mL ^–1）），线性范围宽，可检测8个数量级的抗霍乱（10 ^–13至10 ^–5 g mL ^–1）。关键发现之一是使用老化的氧化还原探针而不是新鲜制备的氧化还原探针提高了VCT检测的灵敏度，此处所述氧化还原探针称为“氧化还原探针老化引起的灵敏度增强”（“氧化还原-PrAISE”）。发现Redox-PrAISE在这些免疫传感器的实际应用中更有用，与传统的临床培养方法相比，对八个真实的霍乱感染水样显示出相当甚至更好的灵敏度。这种免疫传感器显示出对VCT即时诊断的潜在发展的希望。重要的是，这项研究强调了在设计阻抗式免疫传感器时，在电化学传感条件下考虑氧化还原探针性质的重要性。