Thermally treated bare gold nanoparticles for colorimetric sensing of copper ions
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We demonstrate a sensitive and rapid colorimetric assay for selective detection of copper ions based on the strong coordination between Cu(II) ions and the tetrahydroxyaurate anions [Au(OH)4]− on the surface of thermally treated bare gold nanoparticles (GNPs). The method for making the unmodified GNPs is simple and results in a nanomaterial with a highly specific response to Cu(II). The thermal treatment of the bare GNPs and the recognition of Cu(II) ions is accomplished in a single step within 5 min. The presence of Cu(II) causes the color to change from red to purple-blue. The limit of detection (LOD) is 0.04 μM of Cu(II) when using UV–vis spectrometry and ratioing the absorbances at 650 and 515 nm, respectively. The method also is amenable to bare eye (visual) inspection and in this case has an LOD of 2.0 μM of Cu(II).
KeywordsColorimetric sensor Gold nanoparticle Thermal treatment Copper ion Quantification
The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China (21175023), the Program for New Century Excellent Talents in University (NCET-12-0618), the Natural Science Foundation of Fujian Province (2011J01034, 2012J06019), and the Program for New Century Excellent Talents in Fujian Province University (JA11102).
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