State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
Biosens Bioelectron. 2011 Jan 15;26(5):2724-7. doi: 10.1016/j.bios.2010.09.032. Epub 2010 Sep 25.
This work presents an aptasensor for Ochratoxin A (OTA) using unmodified gold nanoparticles (AuNPs) indicator. The assay method is based on the conformation change of OTA's aptamer in phosphate buffered saline (PBS) containing Mg(2+) and OTA, and the phenomenon of salt-induced AuNPs aggregation. A single measurement took only five minutes. Circular dichroism spectroscopic experiments revealed for the first time that upon the addition of OTA, the conformation of OTA's aptamer in PBS buffer changed from random coil structure to compact rigid antiparallel G-quadruplex structure. This compact rigid G-quadruplex structure could not protect AuNPs against salt-induced aggregation, and thus the color change from red to blue could be observed by the naked eye. The linear range of the colorimetric aptasensor covered a large variation of OTA concentration from 20 to 625 nM and the detection limit of 20 nM (3σ) was obtained.
本工作提出了一种基于未修饰金纳米粒子（AuNPs）指示剂的赭曲霉毒素 A（OTA）适体传感器。该测定方法基于在含有 Mg(2+)和 OTA 的磷酸盐缓冲盐水（PBS）中 OTA 适体的构象变化，以及盐诱导的 AuNPs 聚集现象。单次测量仅需五分钟。圆二色光谱实验首次揭示，在加入 OTA 后，PBS 缓冲液中 OTA 适体的构象从无规卷曲结构转变为紧凑刚性反平行 G-四链体结构。这种紧凑刚性的 G-四链体结构不能防止 AuNPs 受到盐诱导的聚集，因此可以通过肉眼观察到颜色从红色变为蓝色。比色适体传感器的线性范围涵盖了 OTA 浓度从 20 到 625 nM 的大范围变化，检测限为 20 nM（3σ）。
