title: Silica Cladding of Ag Nanoparticles for High Stability and Surface-Enhanced Raman Spectroscopy Performance.
abstract: For high-precision biochemical sensing, surface-enhanced Raman spectroscopy (SERS) has been demonstrated to be a highly sensitive spectroscopic analytical method and Ag is considered to be the best material for SERS performance. Due to the high surface activity of Ag nanoparticles, the high stability of Ag nanostructures, especially in moist environments, is one of the key issues that need to be solved. A method for silica (SiO2) cladding of Ag nanoparticles (NPs) is demonstrated here for high sensitivity and long-term stability when putted in aqueous solution. The chemically inert, transparent, hydrophilic, and bio-compatible SiO2 surface acts as the protection layer for the Ag nanoparticles, which can also enhance the Raman intensity to a certain extent. In our study, the Ag@SiO2 core-shell substrate can detect crystal violet solutions with molar concentrations down to 10(-12) M. After 24 h of immersion, the reduction in Raman scattering intensity is about 85 % for sole Ag NP films, compared to 12 % for the Ag coated with a 10-nm SiO2 layer. This thickness was found to be optimum for Ag@SiO2 core-shell substrates with long-term stability and high SERS activity.
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Zhao
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Guo
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Wenyao
authors.initials: W
authors.lastname: Liu
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Tang
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Binzhen
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Chenyang
authors.initials: C
authors.lastname: Xue
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China. liuj@nuc.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
authors.forename: Wendong
authors.initials: W
authors.lastname: Zhang
keywords: Ag@SiO2; Layer thickness; Long-term stability; SERS