title: Porous Au-Ag Nanospheres with High-Density and Highly Accessible Hotspots for SERS Analysis.
abstract: Colloidal plasmonic metal nanoparticles have enabled surface-enhanced Raman scattering (SERS) for a variety of analytical applications. While great efforts have been made to create hotspots for amplifying Raman signals, it remains a great challenge to ensure their high density and accessibility for improved sensitivity of the analysis. Here we report a dealloying process for the fabrication of porous Au-Ag alloy nanoparticles containing abundant inherent hotspots, which were encased in ultrathin hollow silica shells so that the need of conventional organic capping ligands for stabilization is eliminated, producing colloidal plasmonic nanoparticles with clean surface and thus high accessibility of the hotspots. As a result, these novel nanostructures show excellent SERS activity with an enhancement factor of ∼1.3 × 10(7) on a single particle basis (off-resonant condition), promising high applicability in many SERS-based analytical and biomedical applications.
authors.affiliation: Center for Materials Chemistry, Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an, Shaanxi 710054, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Liu
authors.affiliation: Department of Chemistry, University of California , Riverside, California 92521, United States.
authors.forename: Yaocai
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Center for Materials Chemistry, Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an, Shaanxi 710054, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Chongqing Key Laboratory of Multi-scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing 400714, China.
authors.forename: Zhongbo
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Center for Materials Chemistry, Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an, Shaanxi 710054, China.
authors.forename: Qikui
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Department of Materials and Environmental Chemistry, Stockholm University , Stockholm 10691, Sweden.
authors.forename: Haoquan
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Department of Chemistry, University of California , Riverside, California 92521, United States.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Yin
authors.affiliation: Center for Materials Chemistry, Frontier Institute of Science and Technology, Xi'an Jiaotong University , Xi'an, Shaanxi 710054, China.
authors.forename: Chuanbo
authors.initials: C
authors.lastname: Gao
keywords: Porous nanoparticles; dealloying process; hotspots; plasmonic nanoparticles; surface-enhanced Raman scattering