Institute of Photonics, Department of Microelectronic Science and Engineering, Faculty of Science, Ningbo University, Ningbo, 315211, P. R. China.
Institute of Physics, Ningbo University of Technology, Ningbo, 315016, P. R. China.
Sci Rep. 2017 Aug 29;7(1):9795. doi: 10.1038/s41598-017-10262-9.
A facile seed-mediated method was developed to modify core-shell Ag nanosphere@PSPAA with another Ag layer for achieving an enhancement of their surface-enhanced Raman scattering (SERS) activity. Interestingly, an Ag bridge in the polymer shell connected the inner and outer Ag layers, resulting in a mushroom-like nanostructure. The outer Ag grew around the polymer shell to form the cap of the nanomushrooms (NMs) with the extension of the reaction time. The epitaxial growth mechanism of this novel nanostructure was investigated by tuning the type of seed from nanosphere to nanocube and nanorod. With the growth of the outer Ag cap, the SERS intensity of these Ag NMs increased significantly together with the red-shifting and broadening of their typical localized surface plasmon resonance band. Such a phenomenon can be attributed to the formation of SERS hotspots between the inner and outer Ag layers. The Ag NMs were then wrapped with a graphene oxide (GO) shell via static interactions. The GO-wrapped Ag NMs exhibited a further better SERS performance in terms of sensitivity, homogeneity and stability compared with non-wrapped ones, indicating that the heterostructure could be potentially useful for SERS-based immunoassay.
一种简便的种子介导方法被开发用于修饰核壳 Ag 纳米球@PSPAA 与另一个 Ag 层，以实现其表面增强拉曼散射（SERS）活性的增强。有趣的是，聚合物壳中的 Ag 桥将内、外 Ag 层连接起来，形成蘑菇状纳米结构。随着反应时间的延长，Ag 在外层聚合物壳周围生长，形成纳米蘑菇（NMs）的帽。通过调节种子的类型（从纳米球到纳米立方体和纳米棒），研究了这种新型纳米结构的外延生长机制。随着外 Ag 帽的生长，这些 Ag NM 的 SERS 强度显著增强，同时它们的典型局域表面等离子体共振带发生红移和展宽。这种现象可以归因于内、外 Ag 层之间 SERS 热点的形成。然后，通过静态相互作用将氧化石墨烯（GO）壳包裹在 Ag NM 上。与未包裹的 Ag NM 相比，GO 包裹的 Ag NM 在灵敏度、均匀性和稳定性方面表现出更好的 SERS 性能，表明这种异质结构可能在基于 SERS 的免疫分析中具有潜在的应用价值。
