Monodisperse Colloidal Gold Nanorings: Synthesis and Utility for Surface-Enhanced Raman Scattering
Monodisperse Colloidal Gold Nanorings: Synthesis and Utility for Surface-Enhanced Raman Scattering
复制标题
DOI：
10.1021/jp504190d
复制
发表时间：
2014-07-24
影响因子：
3.7
通讯作者：
Du, Henry
中科院分区：
文献类型：
--
作者：
Hu, Yue;Chou, Tsengming;Du, Henry
利用Co纳米粒子(Co NPs)在HAuCl4中的ID链组装的电偶取代反应，合成了高度单分散的胶体Au纳米环(Au NRs)。当长宽比从3.8+/-0.5增加到7.1+/-1.8时，Au-NRS显示出可调谐的局域表面等离子体共振(LSPR)波长，波长范围为651-760 nm，这与用时域有限差分(FDTD)方法计算的结果一致。FDTD计算表明，在间隔较好的Au-NRs腔内有很强的场强增强，并且在相邻的Au-Nr之间存在热斑。Au-NRs对表面增强拉曼散射(SERS)具有单独的活性。我们发现，在Co纳米粒子ID链组装的粒子交界处，稠密填充的聚乙烯吡咯烷酮(PVP)稳定剂对AuCl4扩散的空间位阻对Au-NR的形成是至关重要的。我们进一步证明，在我们的研究系统中，分析物是否经历热点效应强烈地取决于它进入连接点的能力，从而它与Au NRS表面的PVP的亲和力。
Highly monodisperse colloidal Au nanorings (Au NRs) were synthesized via galvanic replacement reaction of ID chain assembly of Co nanoparticles (Co NPs) in HAuCl4. The Au NRs exhibited tunable localized surface plasmon resonance (LSPR) wavelengths ranging from 651 to 760 nm as the aspect ratio increased from 3.8 +/- 0.5 to 7.1 +/- 1.8, consistent with calculations using the finite-difference time domain (FDTD) method. The FDTD calculations indicated intense field enhancement within the cavity of well-separated Au NRs as well as the presence of hot spots between closely situated Au NRs. The Au NRs are individually active for surface-enhanced Raman scattering (SERS). We show that the steric hindrance of densely packed poly(vinylpyrrolidone) (PVP) stabilizer at the particle junctions of the ID chain assembly of Co NPs to AuCl4- diffusion is of critical importance for Au NR formation. We further demonstrate that whether an analyte experiences the hot-spot effect or not depends strongly on its ability to enter the junction points and thus its affinity to PVP on the surface of Au NRs in our system of study.