Key Laboratory for Analytical Science of Food Safety and Biology, MOE, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China.
Anal Methods. 2024 Mar 14;16(11):1570-1578. doi: 10.1039/d3ay02157b.
In this paper, a novel and sensitive electrochemical aptasensor for sulfadimethoxine (SDM) detection has been designed based on the triple helix structure/exonuclease I (Exo I)-assisted double signal amplification strategy. The aptamer probe (Apt) hybridizes with the signal transduction probe (STP) on the electrode to form a rigid double-stranded DNA (dsDNA) structure, so that the STP remains upright and methylene blue (MB) on the STP is far away from the electrode surface, resulting in a delicate current signal. In the presence of SDM, the SDM and Apt combine into a complex, leading to the transfer of the Apt and the exposure of the STP. Meanwhile, the added Exo I can digest the Apt to realize the cyclic amplification of SDM. After the addition of the signal probe (SP), a triple helix structure between the SP and STP is formed under acidic conditions, and MB on the STP and SP collide with the electrode surface to generate a strong electrochemical signal. The proposed aptasensor combines the features of the triple helix structure and Exo I to achieve double signal amplification for the sensitive detection of SDM with a wide linear range of 0.05-1000 ng mL and a low detection limit of 0.02 ng mL. Furthermore, it has been successfully used to detect SDM in milk and lake water samples.
本文基于三螺旋结构/核酸外切酶 I（Exo I）辅助的双信号放大策略，设计了一种用于磺胺二甲氧嘧啶（SDM）检测的新型灵敏电化学适体传感器。适体探针（Apt）与电极上的信号转导探针（STP）杂交形成刚性双链 DNA（dsDNA）结构，使 STP 保持直立，且 STP 上的亚甲蓝（MB）远离电极表面，从而产生精细的电流信号。在存在 SDM 的情况下，SDM 与 Apt 结合形成复合物，导致 Apt 转移并暴露出 STP。同时，加入的 Exo I 可以消化 Apt 以实现 SDM 的循环放大。在添加信号探针（SP）后，在酸性条件下 SP 和 STP 之间形成三螺旋结构，且 STP 和 SP 上的 MB 与电极表面碰撞，产生强烈的电化学信号。所提出的适体传感器结合了三螺旋结构和 Exo I 的特点，实现了对 SDM 的灵敏检测，具有 0.05-1000 ng mL 的宽线性范围和 0.02 ng mL 的低检测限。此外，它已成功用于检测牛奶和湖水样品中的 SDM。
