Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun Road, Houston, TX, 77204, USA.
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, 77030, TX, USA.
Nat Commun. 2020 Nov 16;11(1):5805. doi: 10.1038/s41467-020-19678-w.
Label-free optical imaging of nanoscale objects faces fundamental challenges. Techniques based on propagating surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) have shown promises. However, challenges remain to achieve diffraction-limited resolution and better surface localization in SPR imaging. LSPR imaging with dark-field microscopy on metallic nanostructures suffers from low light throughput and insufficient imaging capacity. Here we show ultra-near-field index modulated PlAsmonic NanO-apeRture lAbel-free iMAging (PANORAMA) which uniquely relies on unscattered light to detect sub-100 nm dielectric nanoparticles. PANORAMA provides diffraction-limited resolution, higher surface sensitivity, and wide-field imaging with dense spatial sampling. Its system is identical to a standard bright-field microscope with a lamp and a camera - no laser or interferometry is needed. In a parallel fashion, PANORAMA can detect, count and size individual dielectric nanoparticles beyond 25 nm, and dynamically monitor their distance to the plasmonic surface at millisecond timescale.
无标记纳米物体光学成像面临着重大挑战。基于传播表面等离子体共振（SPR）和局域表面等离子体共振（LSPR）的技术显示出了一定的前景。然而，在 SPR 成像中实现衍射极限分辨率和更好的表面定位仍然存在挑战。在金属纳米结构上采用暗场显微镜的 LSPR 成像存在着低光透过率和不足的成像能力的问题。在这里，我们展示了超近场指数调制等离子体纳米孔无标记成像（PANORAMA），它独特地依赖于非散射光来检测亚 100nm 的介电纳米颗粒。PANORAMA 提供了衍射极限分辨率、更高的表面灵敏度和具有密集空间采样的宽场成像。它的系统与带有灯和相机的标准明场显微镜完全相同——不需要激光或干涉测量。以并行的方式，PANORAMA 可以检测、计数和测量超过 25nm 的单个介电纳米颗粒，并以毫秒级的时间尺度动态监测它们到等离子体表面的距离。
