Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan, Shanxi, 030051, China.
Nanoscale Res Lett. 2016 Dec;11(1):403. doi: 10.1186/s11671-016-1604-5. Epub 2016 Sep 15.
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.
对于高精度生化传感，表面增强拉曼光谱（SERS）已被证明是一种高灵敏度的光谱分析方法，而 Ag 被认为是 SERS 性能的最佳材料。由于 Ag 纳米粒子具有很高的表面活性，Ag 纳米结构的高稳定性，特别是在潮湿环境中，是需要解决的关键问题之一。这里展示了一种用于 Ag 纳米粒子（NPs）的二氧化硅（SiO2）包覆的方法，以提高其在水溶液中的灵敏度和长期稳定性。化学惰性、透明、亲水和生物相容性的 SiO2 表面作为 Ag 纳米粒子的保护层，也可以在一定程度上增强 Raman 强度。在我们的研究中，Ag@SiO2 核壳基底可以检测摩尔浓度低至 10（-12）M 的结晶紫溶液。在 24 小时的浸泡后，单独的 Ag NP 薄膜的 Raman 散射强度减少了约 85%，而涂有 10nm SiO2 层的 Ag 减少了 12%。对于具有长期稳定性和高 SERS 活性的 Ag@SiO2 核壳基底，发现这种厚度是最佳的。
