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Multi-branch Au/Ag bimetallic core–shell–satellite nanoparticles as a versatile SERS substrate: the effect of Au branches in a mesoporous silica interlayer

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Abstract

We synthesized a novel bimetallic core–shell–satellite surface-enhanced Raman scattering (SERS) substrate (AuNS@mSiO2@AgNP) that consists of a gold nanostar (AuNS) core, a mesoporous silica (mSiO2) shell and a layer of silver nanosphere (AgNP) satellites. The core–shell–satellite nanostructure was formed by growing branches in the mSiO2 shell of mSiO2 coated gold nanospheres (AuNP@mSiO2) using AuNPs as the seeds, and the subsequent deposition of AgNPs on the mSiO2 surface. The growth of AuNSs in mSiO2 leads to the formation of a large number of closely spaced branches which provide enormous hotspots; and by varying the length of the branches, the nanogap distance between the AuNS core and the AgNP satellites can be carefully adjusted. Besides, mSiO2 could allow the infiltration of the analyte into the nanogap area that has high SERS enhancement. To demonstrate the feasibility of the SERS substrate, the bimetallic core–shell–satellite nanostructures were used for the label-free detection of a pesticide named thiram. The AuNS@mSiO2@AgNP was shown to have excellent selectivity and SERS activity which is significantly higher than that of AuNS@mSiO2, mSiO2@AgNP and AuNP@mSiO2@AgNP. This method exhibits a good linear response when the thiram concentration ranges from 10−9 M to 10−3 M, and the limit of detection (LOD) is 10−9 M, showing that the bimetallic core–shell–satellite nanostructure is a promising SERS substrate.

Graphical abstract: Multi-branch Au/Ag bimetallic core–shell–satellite nanoparticles as a versatile SERS substrate: the effect of Au branches in a mesoporous silica interlayer

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Publication details

The article was received on 20 Aug 2017, accepted on 11 Oct 2017 and first published on 12 Oct 2017


Article type: Paper
DOI: 10.1039/C7TC03788K
Citation: J. Mater. Chem. C, 2017, Advance Article
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    Multi-branch Au/Ag bimetallic core–shell–satellite nanoparticles as a versatile SERS substrate: the effect of Au branches in a mesoporous silica interlayer

    J. Zhao, L. Long, G. Weng, J. Li, J. Zhu and J. Zhao, J. Mater. Chem. C, 2017, Advance Article , DOI: 10.1039/C7TC03788K

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