Nanophotonics Research Center, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
College of Physics and Optoelectronics Engineering, Shenzhen University, Shenzhen 518060, China.
Biosensors (Basel). 2022 Apr 24;12(5):270. doi: 10.3390/bios12050270.
Surface-enhanced Raman scattering (SERS) detection requires dense hotspots and a uniform distribution of analytes to obtain a stable signal with good repeatability. However, due to the coffee-ring effect on the hydrophilic substrate, and the difficulty of droplet manipulation on the superhydrophobic substrate, few substrates can ensure that the analytes are evenly distributed. In this work, we develop a method that can efficiently enrich plasmonic hotspots for SERS measurement on the superhydrophobic concave dome array (SCDA). The SCDA is formed by spraying hydrophobic silica nanoparticles onto a polydimethylsiloxane (PDMS) slab with a concave dome array that can physically confine the droplets and overcome the coffee-ring effect. During droplet evaporation, the SCDA is driven by a horizontal spinner, and the droplets spin on the SCDA, enabling the plasmonic nanoparticles to become closely packed to form the SERS hotspots. The limit of detection (LOD) of the dynamic-enriched SERS hotspots for crystal violet and methylene blue can reach up to 10 M. Moreover, the LOD for melamine in milk can reach 5 × 10 M, which is lower than the safety threshold defined by the Food and Drug Administration (FDA). Based on this SERS platform, an effective, low-cost, and simple method for SERS detection in analytical chemistry and food safety is highly expected.
表面增强拉曼散射（SERS）检测需要密集的热点和分析物的均匀分布，以获得具有良好重复性的稳定信号。然而，由于亲水基底上的咖啡环效应，以及在超疏水基底上难以操控液滴，很少有基底可以确保分析物均匀分布。在这项工作中，我们开发了一种方法，可以在超疏水凹面穹顶阵列（SCDA）上有效地富集等离子体热点，用于 SERS 测量。SCDA 是通过将疏水性二氧化硅纳米颗粒喷涂到具有凹面穹顶阵列的聚二甲基硅氧烷（PDMS）平板上形成的，该凹面穹顶阵列可以物理限制液滴并克服咖啡环效应。在液滴蒸发过程中，SCDA 由水平旋转器驱动，液滴在 SCDA 上旋转，使等离子体纳米颗粒紧密堆积形成 SERS 热点。对于结晶紫和亚甲基蓝，动态富集 SERS 热点的检测限（LOD）可达 10 M。此外，牛奶中三聚氰胺的 LOD 可达 5×10 M，低于食品和药物管理局（FDA）定义的安全阈值。基于这个 SERS 平台，有望在分析化学和食品安全领域实现一种有效、低成本、简单的 SERS 检测方法。
