In horseradish peroxidase (HRP)-based electrochemical immunosensing, an appropriate HRP substrate needs to be chosen to obtain a high electrochemical signal-to-background ratio. This is limited by the unwanted electrochemical reduction of H₂O₂, oxidation of the substrate, and the slow electrochemical reduction of the product. Herein, we report acetaminophen (AMP) as a new HRP substrate that allows for highly sensitive immunosensing. Electrochemical behavior and immunosensing performance using AMP are compared with those using the most popular HRP substrate, hydroquinone (HQ). To maintain a high electrocatalytic activity even at an electrode modified with an immunosensing layer, an indium tin oxide electrode partially modified with reduced graphene oxide is employed. AMP allows for a higher signal-to-background ratio than HQ, because the formal potential of AMP is 0.28 V higher than that of HQ and the redox reaction of AMP is as reversible as that of HQ, resulting in a lower detection limit in a sandwich-type immunoassay using AMP for thyroid-stimulating hormone detection. The calculated detection limit is ~0.2 pg/mL. The use of AMP as an HRP substrate is especially promising for highly sensitive electrochemical immunoassays.

在基于辣根过氧化物酶（HRP）的电化学免疫传感中，需要选择合适的HRP底物以获得较高的电化学信噪比。这受到H ₂ O ₂的不希望的电化学还原的限制，底物的氧化和缓慢的电化学还原产物。在本文中，我们报道了对乙酰氨基酚（AMP）作为一种新的HRP底物，可实现高度灵敏的免疫传感。将使用AMP的电化学行为和免疫感应性能与使用最流行的HRP底物对苯二酚（HQ）进行比较。为了即使在用免疫传感层改性的电极上也保持高的电催化活性，采用了用还原的氧化石墨烯部分改性的铟锡氧化物电极。由于AMP的形式电位比HQ高0.28 V，并且AMP的氧化还原反应与HQ一样可逆，因此AMP的信噪比比HQ高。使用AMP的夹心型免疫分析法检测甲状腺刺激激素。计算出的检出限为〜0.2 pg / mL。AMP作为HRP底物的用途对于高度灵敏的电化学免疫分析特别有希望。