Zhuo Ming, Wang Chaoguang, Dong Peitao, Chen Jian, Wu Xuezhong
College of Mechatronics Engineering and Automation, National University of Defense Technology Changsha Hunan 410073 P. R. China
RSC Adv. 2019 Oct 30;9(60):35011-35021. doi: 10.1039/c9ra02371b. eCollection 2019 Oct 28.
Hybrid SERS configurations, which combine manufactured metallic chips with nanoparticles, have emerged as powerful and promising SERS substrates because they not only provide cost-effective and high-yield manufacture, but also demonstrate excellent sensitivity and outstanding reproducibility. Herein, a plasmonic hybrid structure, a particle on an Au film over nanoparticles (particle-AuFON) configuration, was studied for SERS application. In a previous study, we constructed a hybrid substrate by grafting Au@Ag core-shell NPs onto the AuFON structure. In this study, the hybrid substrate is designed and simulated to optimize electromagnetic enhancement while also affording exceptional uniformity, repeatability and stability, which are essential factors in SERS applications. This hybrid substrate provides good SERS performance with a detection limit of 1 × 10 M, which is 100-fold improvement compared to AuFON substrate or Au@Ag NPs. The excellent signal enhancement originates from the hotspot improvement and densification, as visualized by the FDTD calculations. Additional hotspots were created at the gaps between the Au@Ag NPs and the AuFON, thus improving the density of hotspots. Moreover, the intensity of the hotspots was improved due to EM coupling between the original hotspots and additional hotspots. To validate the feasibility of this hybrid substrate in SERS-based detection, melamine was detected as an example. The detection limit was 10 nM, which was much lower than the maximum limit of melamine in infant formula (1 ppm) legislated by the governments of both the United States and China. A calibration curve was plotted between the SERS intensity and melamine concentration with a correlation coefficient of 0.98. This hybrid SERS substrate shows great potential in SERS-based sensing and imaging, as it provides high sensitivity and outstanding reproducibility with a simple fabrication procedure, facilitating the cost-effective and high-yield manufacture of SERS substrates.
将人造金属芯片与纳米颗粒相结合的混合表面增强拉曼光谱（SERS）配置，已成为强大且有前景的SERS基底，因为它们不仅能实现经济高效的大规模制造，还展现出出色的灵敏度和卓越的可重复性。在此，研究了一种等离子体混合结构——纳米颗粒上的金膜上的粒子（particle-AuFON）配置，用于SERS应用。在之前的一项研究中，我们通过将金@银核壳纳米粒子嫁接到AuFON结构上构建了一种混合基底。在本研究中，对该混合基底进行了设计和模拟，以优化电磁增强，同时还能提供出色的均匀性、可重复性和稳定性，这些都是SERS应用中的关键因素。这种混合基底具有良好的SERS性能，检测限为1×10⁻⁸ M，与AuFON基底或金@银纳米粒子相比提高了100倍。优异的信号增强源于热点的改善和致密化，这通过时域有限差分（FDTD）计算得以可视化。在金@银纳米粒子与AuFON之间的间隙处产生了额外的热点，从而提高了热点的密度。此外，由于原始热点与额外热点之间的电磁耦合，热点的强度也得到了提高。为了验证这种混合基底在基于SERS的检测中的可行性，以三聚氰胺为例进行了检测。检测限为10 nM，远低于美国和中国政府规定的婴儿配方奶粉中三聚氰胺的最大限量（1 ppm）。绘制了SERS强度与三聚氰胺浓度之间的校准曲线，相关系数为0.98。这种混合SERS基底在基于SERS的传感和成像方面显示出巨大潜力，因为它通过简单的制造工艺提供了高灵敏度和出色的可重复性，有利于SERS基底的经济高效大规模制造。
