Liu Yanting, Zhou Jun, Wang Binbing, Jiang Tao, Ho Ho-Pui, Petti Lucia, Mormile Pasquale
Institute of Photonics, Faculty of Science, Ningbo University, Ningbo 31 5211, Zhejiang, China.
Phys Chem Chem Phys. 2015 Mar 14;17(10):6819-26. doi: 10.1039/c4cp05642f.
Novel Au@Ag core-shell nanocubes (NCs) were successfully prepared by the controlled epitaxial growth of Ag shells onto Au nanoellipsoids (NEs) in the presence of surfactants. The growth mechanism of the Au@Ag core-shell NCs was systematically investigated by analyzing their morphology, optical properties, and crystallography. The localized surface plasmon resonance (LSPR) characteristics and the electric field distribution of the Au@Ag core-shell NCs were studied using the finite element method (FEM) based on the plasmon hybridization theory. Compared with pure Ag NCs, the absorption spectrum of the Au@Ag core-shell NCs exhibits a red shift and a weak shoulder near 550 nm, and the notable enhancement of electric field occurs around the corners along the long-axis of the Au ellipsoidal core because of plasmonic resonant coupling. Surface-enhanced Raman scattering (SERS) of the Au@Ag core-shell NCs labeled with 4-mercaptobenzoic acid molecules reveals that the bimetallic core-shell NCs possess efficient SERS activity with an enhancement factor EF = 2.27 × 10(6), thus confirming the possibility of using the Au@Ag core-shell NCs as a stable probe for SERS-based biosensing applications.
通过在表面活性剂存在下将银壳层可控地外延生长在金纳米椭球体（NEs）上，成功制备了新型金@银核壳纳米立方体（NCs）。通过分析金@银核壳纳米立方体的形态、光学性质和晶体学，系统地研究了其生长机制。基于等离子体杂化理论，采用有限元方法（FEM）研究了金@银核壳纳米立方体的局域表面等离子体共振（LSPR）特性和电场分布。与纯银纳米立方体相比，金@银核壳纳米立方体的吸收光谱在550nm附近呈现红移和弱肩峰，并且由于等离子体共振耦合，在金椭球形核的长轴拐角处出现显著的电场增强。用4-巯基苯甲酸分子标记的金@银核壳纳米立方体的表面增强拉曼散射（SERS）表明，双金属核壳纳米立方体具有高效的SERS活性，增强因子EF = 2.27×10(6)，从而证实了将金@银核壳纳米立方体用作基于SERS的生物传感应用的稳定探针的可能性。
