Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada.
Lab Chip. 2018 Feb 13;18(4):568-573. doi: 10.1039/c7lc01193h.
Fluorescence microscopy uniquely enables physical and biological research in micro- and nanofluidic systems. However, in channels with depths below 10 nm, the limited number of fluorophores results in fluorescence intensity below the detection limit of optical microscopes. To overcome this barrier, we applied Fabry-Pérot interference to enhance fluorescence intensity with a silicon nitride layer below the sub-10 nm channel. A silicon nitride layer of suitable thickness can selectively enhance both absorption and emission wavelengths, leading to a fluorescent signal that is enhanced 20-fold and readily imaged with traditional microscopes. To demonstrate this method, we studied the mass transport of a binary solution of ethanol and Rhodamin B in 8 nm nanochannels. The large molecular size of Rhodamin B (∼1.8 nm) relative to the channel depth results in both separation and reduced diffusivity, deviating from behavior at larger scales. This method extends the widely available suite of fluorescence analysis tools and infrastructure to unprecedented sub-10 nm scale with relevance to a wide variety of biomolecular interactions.
荧光显微镜独特地实现了微纳流控系统中的物理和生物研究。然而，在深度低于 10nm 的通道中，由于荧光团数量有限，荧光强度低于光学显微镜的检测极限。为了克服这一障碍，我们在亚 10nm 通道下方应用法布里-珀罗干涉来增强荧光强度。具有合适厚度的氮化硅层可以选择性地增强吸收和发射波长，从而使荧光信号增强 20 倍，并可通过传统显微镜轻松成像。为了验证这种方法，我们研究了二元乙醇和 Rhodamin B 溶液在 8nm 纳米通道中的质量传输。与通道深度相比，Rhodamin B（~1.8nm）的较大分子尺寸导致分离和扩散率降低，偏离了较大尺度的行为。这种方法将广泛可用的荧光分析工具套件和基础设施扩展到前所未有的亚 10nm 尺度，与广泛的生物分子相互作用相关。
