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Updated: May 22, 2026

Synthesis of Near-Infrared Emitting Gold Nanoclusters for Biological Applications
Published on: March 22, 2020
Colorimetric determination of hypochlorite with unmodified gold nanoparticles through the oxidation of a stabilizer
Jia Zhang1, Xiaolei Wang, Xiurong Yang
1State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China.
Abstract:
In this article, we report a colorimetric approach for the determination of hypochlorite (OCl(-)) with gold nanoparticles (Au NPs). The test proceeds as two individual steps and selectivity is developed based on the strong oxidizing ability of hypochlorite. In concentrated phosphate buffer (PB), the red solution of citrate-capped Au NPs could be stabilized by the chemisorption of 11-mercaptoundecanoic acid (MUA), without which the colloidal suspension turned blue because of salt-induced particles aggregation. However, by its oxidizing power, OCl(-) converted the alkanethiol to a sulfonate derivative, which could not protect Au NPs from aggregation, thereby a blue solution was observed after the subsequent addition of Au suspension. With this method and under the optimal conditions (28 nm Au NP, 50 mM PB, pH 7.0, and 10 min for the colorimetric response), 1.5 μM of OCl(-) can be easily visualized by the naked eye. This sensitive and selective colorimetric assay opens up a fresh insight of facile, rapid, and reliable detection of OCl(-), and may find its future application in the monitoring of OCl(-)/HOCl in waters sanitized by chlorine or hypochlorite compounds.
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