Ethanol-Induced Formation of Silver Nanoparticle Aggregates for Highly Active SERS Substrates and Application in DNA Detection

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• 作者：Lanlan Sun ; Yonghai Song ; Li Wang ; Cunlan Guo ; Yujing Sun ; Zhelin Liu ; Zhuang Li
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：February 7, 2008
• 年：2008
• 卷：112
• 期：5
• 页码：1415 - 1422
• 全文大小：387K
• 年卷期：v.112,no.5(February 7, 2008)
• ISSN：1932-7455

文摘

A controllable silver nanoparticle aggregate system has been synthesized by adding different amounts ofethanol to cetyltrimethylammonium bromide (CTAB) capped silver nanoparticles (Ag-nps), which could beused as highly efficient surface-enhanced Raman scattering (SERS) active substrates. This ethanol-inducedaggregation can be attributed to preferential dissolution of CTAB into ethanol, which leads a partial removalof the protective CTAB layer on Ag-nps. The optical and morphological properties of these aggregates undervarious volumes of ethanol were explored via UV-vis spectroscopy and atomic force microscopy. Twocommon probe molecules, Rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) were used for testing theSERS activity on these substrates at very low concentrations. It was found that the SERS enhancement abilityis dependent on the ethanol volume used. The SERS enhancement factors of 4-ATP were estimated to be aslarge as 8.1 × 10⁸ for b₂ vibration modes and 6.8 × 10⁶ for a₁ vibration modes. Good stability of the substrateswas demonstrated by measuring the Raman activity with time. The optimized SERS-active substrate with thelargest enhancement ability shown in this study could be used to detect double-strand DNA. The great advantagefor this SERS-based DNA detection is that a dye label is not needed. It showed the potential of this Ag-npsaggregate system as a convenient and powerful SERS-active substrate for DNA detection.