Key Laboratory of Water Pollution Treatment and Resource Reuse of Hainan Province, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou, 571158, PR China.
Key Laboratory of Optic-Electric Sensing and Analytical Chemistry for Life Science, Shandong Key Laboratory of Biochemical Analysis, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, 266042, PR China.
Anal Chim Acta. 2020 Jun 29;1118:1-8. doi: 10.1016/j.aca.2020.04.042. Epub 2020 Apr 20.
In this paper a photoelectrochemical (PEC) aptasensor based on specific recognition with conformational changed after the target Cd(II) identification was fabricated. A ZnO and reduced graphene oxide (ZnO-rGO) nanocomposite with enhanced PEC activity was designed as photoactive material. After the further incorporation of gold nanoparticles (AuNPs) with ZnO-rGO nanocomposite, the enhanced photocurrent signal could be detected owing to the localized surface plasmon resonance and good conductivity of AuNPs. In addition, AuNPs were used as anchors for immobilization of -SH modified aptamer S1. After that aptamer S2 was paired with S1 sequence to form complementary double stranded DNA (dsDNA) on the electrode surface. Methylene blue (MB) was acted as sensitizer and assembled in dsDNA structure to amplify photocurrent response. When Cd(II) was bound to the aptamer presented on the sensing interface, S2 specifically recognized and captured Cd(II), which resulted in the unwinding of dsDNA structure and the separation of MB molecules from the electrode surface with photocurrent response decreased. The photocurrent was detected by a double-working-electrode system, which used the modified electrode as the first working electrode and glassy carbon electrode (GCE) as the second working electrode. Dopamine (DA) was added to the electrolyte and acted as the electron donor, which could be oxidized on the modified electrode and reduced on the GCE to form a cyclic reaction, leading to the enhanced photocurrent response with improved photocurrent stability. This MB sensitized PEC aptasensor exhibited a high sensitivity with a detection limit of 1.8 × 10 mol/L (3σ). Thus, a highly sensitive aptasensor with double-working-electrode detection method for Cd(II) determination were established and further applied to the water samples analysis.
本文制备了一种基于目标 Cd(II) 识别后构象变化的特定识别的光电化学（PEC）适体传感器。设计了具有增强 PEC 活性的 ZnO 和还原氧化石墨烯（ZnO-rGO）纳米复合材料作为光活性材料。在进一步将具有 ZnO-rGO 纳米复合材料的金纳米粒子（AuNPs）掺入后，由于局域表面等离子体共振和 AuNPs 的良好导电性，可以检测到增强的光电流信号。此外，AuNPs 用作 -SH 修饰的适体 S1 的固定化锚。之后，将适体 S2 与 S1 序列配对，在电极表面形成互补的双链 DNA（dsDNA）。亚甲蓝（MB）作为敏化剂并组装在 dsDNA 结构中，以放大光电流响应。当 Cd(II) 与传感界面上呈现的适体结合时，S2 特异性识别并捕获 Cd(II)，导致 dsDNA 结构展开，并且 MB 分子从电极表面分离，光电流响应降低。通过双工作电极系统检测光电流，其中修饰电极用作第一工作电极，玻碳电极（GCE）用作第二工作电极。将多巴胺（DA）添加到电解质中并作为电子供体，其可以在修饰电极上被氧化并在 GCE 上被还原以形成循环反应，从而导致光电流响应增强，光电流稳定性提高。该 MB 敏化 PEC 适体传感器具有 1.8×10 -mol/L（3σ）的高检测限，表现出高灵敏度。因此，建立了一种具有双工作电极检测方法的高灵敏度适体传感器，用于 Cd(II) 测定，并进一步应用于水样分析。
