title: Controllable preparation of core-shell Au-Ag nanoshuttles with improved refractive index sensitivity and SERS activity.
abstract: Recent studies have conclusively shown that the plasmonic performance of Au nanostructures can be enhanced by incorporating Ag. Here, we developed a simple and robust approach for preparing core-shell Au-Ag nanoshuttles (NSs) using single-crystal Au nanorods (NRs) as cores. Upon tailoring the temperature of the reaction system containing alkaline glycine buffer (pH 8.5), exceptionally monodisperse Au-Ag NSs with sharp tips and tunable shell thickness could be routinely achieved in high yield through an epitaxial growth process. In particular, high-resolution transmission electron microscopy and nitric acid corrosive experiments revealed that the shells of these NSs consisted of a homogeneous Au-Ag alloy, rather than pure Ag or Au as previously reported. It was found that glycine played an important role in determining the final metal contents of the shell by regulating the reduction kinetics. In addition, the obatined Au-Ag NSs with sharp tips were shown to have significantly improved refractive index sensitivity and surface-enhanced Raman scattering activity relative to the original Au NRs, making these materials promising for biomedical applications, such as biosensing and biolabeling.
authors.affiliation: State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, P. R. China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Bai
authors.forename: Jianfei
authors.initials: J
authors.lastname: Sun
authors.forename: Renchao
authors.initials: R
authors.lastname: Che
authors.forename: Lina
authors.initials: L
authors.lastname: Xu
authors.forename: Chenyue
authors.initials: C
authors.lastname: Yin
authors.forename: Zhirui
authors.initials: Z
authors.lastname: Guo
authors.forename: Ning
authors.initials: N
authors.lastname: Gu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*
chemical_list: D012834:Silver; D006046:Gold