AbstractThis article reports on a novel aptamer-based platform for the quantitation of urea by using an aptamer with high affinity and selectivity for urea. The surface of a glassy carbon electrode (GCE) was modified by drop casting a cocktail consisting of carbon nanotubes and reduced graphene oxide (rGO) decorated with platinum-gold nanoparticles. The urea aptamer was then immobilized on the nanocomposite via covalent conjugation. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to trace the modification of the GCE. Binding of urea caused the aptamer to be folded, and this result in an inhibition of the interfacial charge transfer rate when using hexacyanoferrate as an electrochemical redox probe. The change in redox current was quantified by differential pulse voltammetry, typically at a working voltage of 0.22 V vs. Ag/AgCl. The assay has a 1.9 pM detection limit, and the response is linear up to 150 nM concentration of urea. The superior selectivity and affinity of aptamer-modified GCE makes it a most useful tool for analysis of urea present in very low concentrations. Graphical abstractSchematic representation of different steps of aptasensor fabrication.

中文翻译：

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用碳纳米管和还原氧化石墨烯修饰的玻碳电极，用铂金纳米粒子修饰，用于尿素的伏安适配传感

摘要本文报道了一种新型的基于适体的尿素定量平台，该平台使用对尿素具有高亲和力和选择性的适体。通过滴铸由碳纳米管和用铂金纳米粒子装饰的还原氧化石墨烯 (rGO) 组成的混合物，对玻碳电极 (GCE) 的表面进行了修饰。然后通过共价结合将尿素适体固定在纳米复合材料上。采用循环伏安法和电化学阻抗谱来追踪 GCE 的修饰。尿素的结合导致适体折叠，这导致使用六氰基铁酸盐作为电化学氧化还原探针时界面电荷转移速率的抑制。氧化还原电流的变化通过差分脉冲伏安法进行量化，通常工作电压为 0.22 V vs. 银/氯化银。该测定的检测限为 1.9 pM，并且响应高达 150 nM 的尿素浓度。适体修饰的 GCE 的卓越选择性和亲和力使其成为分析极低浓度尿素的最有用工具。图形摘要 适体传感器制造不同步骤的示意图。