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Updated: Feb 26, 2026

Design and Development of Aptamer–Gold Nanoparticle Based Colorimetric Assays for In-the-field Applications
Published on: June 23, 2016
Biothiols induced colour change of silver nanoparticles: A colorimetric sensing strategy
Ambily Thomas1, Unni Sivasankaran1, Krishnapillai Girish Kumar1
1Department of Applied Chemistry, Cochin University of Science and Technology, Kochi 682 022, India.
Abstract:
A sensor for the detection and determination of bio-thiols (glutathione (GSH) and cysteamine (Cyste)) has been developed by integrating the distinguished distance related optical characteristics of silver nanoparticles with the simplicity of colorimetric technique. In presence of these analytes, shift in surface plasmon resonance (SPR) absorption of silver nanoparticles (AgNPs) with change in its colour was observed. Yellow coloured AgNPs solution becomes colourless in presence of GSH and changes to red in presence of Cyste. FTIR, TEM and DLS studies were used to confirm the mechanism. The difference in absorption of AgNPs in the absence and presence of GSH was found to vary linearly in the range 1.00×10-5M to 5.00×10-7M concentration range with limit of detection at 3.68×10-7M. The method can also be applied to quantify Cyste in the range 1.10×10-6M to 5.00×10-8M with limit of detection at 1.80×10-8M. The utility of the proposed colorimetric assay is validated by determination of GSH and Cyste in artificial blood serum.
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