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Updated: Feb 12, 2026

Design and Development of Aptamer–Gold Nanoparticle Based Colorimetric Assays for In-the-field Applications
Published on: June 23, 2016
Colorimetric and visual determination of Au(III) ions using PEGylated gold nanoparticles
Kunhao Yang1, Long Pan1, Lingling Gong1
1School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
Abstract:
A highly selective method is described for the colorimetric determination of Au(III) ions in acidic solution using gold nanoparticles (AuNPs) functionalized with thiolated methoxy poly(ethylene glycol) (mPEG). The presence of Au(III) induces the aggregation of the PEG-AuNPs, and this is accompanied by a color change from wine red to blue, and a decrease in absorbance at 525 nm. This can be monitored spectrophotometrically and visually. Absorbance at 525 nm linearly drops in the 0.50 to 1.75 mg·L-1 Au(III) concentration range, with a 0.25 mg·L-1 detection limit. The method is surprisingly selective over other metal ions. It was successfully applied to the analysis of ore samples. Graphical Abstract ᅟ.
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