Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011, USA.
Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Biosens Bioelectron. 2018 Jun 1;107:224-229. doi: 10.1016/j.bios.2018.02.038. Epub 2018 Feb 17.
The rapid growth of point-of-care tests demands for biosensors with high sensitivity and small size. This paper demonstrates an optofluidic metasurface that combines silicon-on-insulator (SOI) nanophotonics and nanofluidics to realize a high-performance, lateral flow-through biosensor. The metasurface is made of a periodic array of silicon nanoposts on an SOI substrate, and functionalized with specific receptor molecules. Bonding of a polydimethylsiloxane slab directly onto the surface results in an ultracompact biosensor, where analyte solutions are restricted to flow only in the space between the nanoposts. No flow exists above the nanoposts. This sensor design overcomes the issue with diffusion-limited detection of many other biosensors. The lateral flow-through feature, in conjunction with high-Q resonance modes associated with optical bound states of the metasurface, offers an improved sensitivity to subtle molecule-bonding induced changes in refractive index. The device exhibits a resonance mode around 1550 nm wavelength and provides an index sensitivity of 720 nm/RIU. Biosensing is conducted to detect the epidermal growth factor receptor 2 (ErbB2), a protein biomarker for early-stage breast cancer screening, by monitoring resonance wavelength shifts in response to specific analyte-ligand binding events at the metasurface. The limit of detection of the device is 0.7 ng mL for ErbB2.
即时检测的快速发展对具有高灵敏度和小尺寸的生物传感器提出了要求。本文展示了一种基于硅的光学超表面，结合了硅的纳米光子学和纳流控技术，实现了高性能的侧向流动式生物传感器。该超表面由 SOI 衬底上的周期性硅纳米柱阵列组成，并通过特定的受体分子进行功能化。将聚二甲基硅氧烷（PDMS）薄片直接键合到表面上，得到一个超紧凑的生物传感器，其中分析物溶液仅在纳米柱之间的空间中流动。纳米柱上方没有流动。这种传感器设计克服了许多其他生物传感器在扩散限制检测方面的问题。侧向流动的特点，结合与光学束缚态相关的高 Q 共振模式，为检测折射率微小的分子键合诱导变化提供了更高的灵敏度。该器件在 1550nm 波长附近显示出一个共振模式，并提供 720nm/RIU 的折射率灵敏度。通过监测超表面上特定分析物-配体结合事件引起的共振波长位移，该器件用于检测表皮生长因子受体 2（ErbB2），这是早期乳腺癌筛查的一种蛋白质生物标志物，以进行生物传感。该器件对 ErbB2 的检测限为 0.7ng/mL。
