Department of Chemistry, Sultan Qaboos University, Box 36, Al-Khod 123, Oman.
Analyst. 2018 Apr 16;143(8):1835-1845. doi: 10.1039/c7an02092a.
We report the construction of a novel electrochemical femtomolar aptasensing APT-ERGO/GCE interface based on the covalent immobilization of 38-mer amine-functionalized (NH2-APT) 17β-estradiol (E2) DNA aptamers on a graphene amplifying platform. Graphene oxide (GO) was synthesized and characterized by using FTIR, UV-vis spectroscopy, XRD spectroscopy, and SEM technique. The strategy for the construction of the E2-aptasensing interface involves in a three-step modification process. (i) First, we carried out the electrochemical reduction of GO on the GCE electrode to form ERGO/GCE. (ii) Then, as an impact strategy, the E2-aptamers (NH2-APT) were further immobilized on the surface of the ERGO/GCE interface through electrochemical reduction of surface-functionalized diazonium salts. This step includes electrografting of ERGO/GCE by electrochemical reduction of the diazonium salt (ClN2+-Ph-COOH) to obtain the ERGO/GCE-Ph-COOH-modified electrode. (iii) Finally, the free carboxyl groups on the ERGO/GCE-Ph-COOH surface were conjugated with NH2-APT through formation of carbodiimide to afford an aptasensing APT-ERGO/GCE interface. The presence of ERGO as an amplifying platform led to the successful immobilization of E2-aptamers with a surface coverage of 1.9 × 1013 molecule per cm2, which is higher than the values obtained in other reported methods. The constructed aptasensing APT-ERGO/GCE interface was appraised using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The synergetic effect of high affinity and specificity of E2-aptamers and graphene platform was beneficial for the novel femtosensitive label-free electrochemical aptasensing APT-ERGO/GCE interface for the detection of [E2]. The oxidation current peaks at the aptasensing APT-ERGO/GCE interface were proportional to [E2] over two different concentration linearity ranges 1.0 × 10-15 mol L-1-9.0 × 10-12 mol L-1-1.2 × 10-11 mol L-1 to 2.3 × 10-10 mol L-1 with a limit of detection (LOD) of 0.5 × 10-15 mol L-1. This aptasensing APT-ERGO/GCE interface was employed as a femtomolar tool for the determination of [E2] in the environmental and pharmaceutical samples such as wastewater (spiked) and pharmaceutical dosages.
我们报告了一种基于共价固定在石墨烯放大平台上的 38 个碱基胺功能化（NH2-APT）17β-雌二醇（E2）DNA 适体的新型电化学飞摩尔适体传感 APT-ERGO/GCE 界面的构建。通过傅里叶变换红外光谱、紫外可见光谱、X 射线衍射光谱和扫描电子显微镜技术对氧化石墨烯（GO）进行了合成和表征。E2 适体传感界面的构建策略涉及三步修饰过程。（i）首先，我们在 GCE 电极上进行 GO 的电化学还原，形成 ERGO/GCE。（ii）然后，作为一种冲击策略，通过表面功能化重氮盐的电化学还原，将 E2-适体（NH2-APT）进一步固定在 ERGO/GCE 界面上。这一步包括通过电化学还原重氮盐（ClN2+-Ph-COOH）电接枝 ERGO/GCE，得到 ERGO/GCE-Ph-COOH 修饰电极。（iii）最后，通过形成碳二亚胺将 ERGO/GCE-Ph-COOH 表面上的游离羧基与 NH2-APT 偶联，得到适体传感 APT-ERGO/GCE 界面。由于存在石墨烯作为放大平台，E2-适体的成功固定具有 1.9×1013 个分子/cm2 的表面覆盖率，高于其他报道方法获得的值。使用循环伏安法（CV）和电化学阻抗谱（EIS）对构建的适体传感 APT-ERGO/GCE 界面进行了评估。E2-适体和石墨烯平台的高亲和力和特异性的协同作用有利于新型飞敏无标记电化学适体传感 APT-ERGO/GCE 界面用于检测[E2]。在适体传感 APT-ERGO/GCE 界面处的氧化电流峰与[E2]成正比，在两个不同的浓度线性范围 1.0×10-15 mol L-1-9.0×10-12 mol L-1-1.2×10-11 mol L-1-2.3×10-10 mol L-1 内，检测限（LOD）为 0.5×10-15 mol L-1。该适体传感 APT-ERGO/GCE 界面作为一种飞摩尔工具，用于测定环境和药物样品中的[E2]，如废水（加标）和药物剂量。
