Spiky yolk-shell AuAg bimetallic nanorods with uniform interior gap for the SERS detection of thiram residues in fruit juice

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 262; p. 120108
• Main Authors: Zhu, Jian, Zhang, Shuang, Weng, Guo-jun, Li, Jian-jun, Zhao, Jun-wu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-12-2021
• Subjects: Detection; Interior gap; SERS; Spiky yolk-shell AuAg bimetallic nanorods; Thiram; Spiky yolk-shell AuAg bimetallic nanorods; Thiram; Detection; SERS; Interior gap
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2021.120108

The spiky yolk-shell AuAg bimetallic nanorods have a wide detection range of 10−3 to 10−7 M and a low detection limit of 97 nM for thiram.
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•Spiky yolk-shell AuAg nanorods with uniform interior gap were synthesized.•The length and number of the tips could be tuned simultaneously.•The SERS has the strongest enhancement when the outer layer has obvious tips.•This AuAg nanoprobe has a wide detection range and a low detection limit.
By using gold nanorods with silver coating as the sacrificial templates, we prepared spiky yolk-shell AuAg bimetallic nanorods with uniform interior gap via galvanic replacement reaction. The length and number of Au tips of the spiky yolk-shell AuAg nanorods can be tuned simultaneously by altering HAuCl4 volume. The influence of HAuCl4 volume and the sliver layer thickness on the SERS activity of spiky yolk-shell AuAg nanorods are studied. When the sliver layer is thin, the interior gap has not been shielded completely and the outer shell has obvious tips, thus the surface-enhanced Raman scattering (SERS) activity has the strongest enhancement with an enhancement factor (EF) of 4.9 × 105. The spiky yolk-shell AuAg nanorods with the strongest SERS activity are used as SERS substrates to detect thiram. The results demonstrate that the SERS intensity increases linearly with the logarithmic concentration of thiram in the range of 10−3 M to 10−7 M. The detection limit is as low as 97 nM, which is lower than the maximum pesticide residue limit (29 µM) in fruits stipulated by the US Environmental Protection Agency (EPA). Therefore, the spiky yolk-shell AuAg bimetallic nanorods have important practical application value in pesticide detection.