Highly sensitive and selective visual detection of Cr(VI) ions based on etching of silver-coated gold nanorods

• Published in: Nano convergence Vol. 6; no. 1; pp. 1 - 9
• Main Authors: Kim, Dasom, Choi, Eunjin, Lee, Chaedong, Choi, Yejung, Kim, Hoonsub, Yu, Taekyung, Piao, Yuanzhe
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 23.10.2019; Springer Nature B.V; SpringerOpen; 나노기술연구협의회
• Subjects: Chemistry and Materials Science; Chromium; Chromium ion sensing; Colorimetric sensor; Colorimetry; Detection; Doppler effect; Gold; Gold coatings; Gold nanorod; Materials Science; Nanorods; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Novel Nanotechnology-based Medical Toolkits; Red shift; Selectivity; Silver; Silver shell coating; Thickness; Visible spectrum; 고분자공학; Chromium ion sensing; Gold nanorod; Colorimetric sensor; Silver shell coating
• ISSN: 2196-5404; 2196-5404
• DOI: 10.1186/s40580-019-0206-1

We report a visual detection of Cr(VI) ions using silver-coated gold nanorods (AuNR@Ag) as sensing probes. Au NRs were prepared by a seed-mediated growth process and AuNR@Ag nanostructures were synthesized by growing Ag nanoshells on Au NRs. Successful coating of Ag nanoshells on the surface of Au NRs was demonstrated with TEM, EDS, and UV–vis spectrometer. By increasing the overall amount of the deposited Ag on Au NRs, the localized surface plasmon resonance (LSPR) band was significantly blue-shifted, which allowed tuning across the visible spectrum. The sensing mechanism relies on the redox reaction between Cr(VI) ions and Ag nanoshells on Au NRs. As the concentration of Cr(VI) ions increased, more significant red-shift of the longitudinal peak and intensity decrease of the transverse peak could be observed using UV–vis spectrometer. Several parameters such as concentration of CTAB, thickness of the Ag nanoshells and pH of the sample were carefully optimized to determine Cr(VI) ions. Under optimized condition, this method showed a low detection limit of 0.4 μM and high selectivity towards Cr(VI) over other metal ions, and the detection range of Cr(VI) was tuned by controlling thickness of the Ag nanoshells. From multiple evaluations in real sample, it is clear that this method is a promising Cr(VI) ion colorimetric sensor with rapid, sensitive, and selective sensing ability.