Aptamer-based colorimetric biosensing of Ochratoxin A using unmodified gold nanoparticles indicator
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Updated: Jun 7, 2026
Design and Development of Aptamer–Gold Nanoparticle Based Colorimetric Assays for In-the-field Applications
Published on: June 23, 2016
Cheng Yang1, Yong Wang, Jean-Louis Marty
1State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.
Abstract:
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.
