Ohannesian Nareg, Li Jingting, Misbah Ibrahim, Zhao Fusheng, Shih Wei-Chuan
Department of Electrical and Computer Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
Department of Biomedical Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204, United States.
ACS Omega. 2020 Dec 11;5(50):32481-32489. doi: 10.1021/acsomega.0c04610. eCollection 2020 Dec 22.
Directed concentrating of micro- and nanoparticles via laser-generated plasmonic microbubbles in a liquid environment is an emerging technology. For effective heating, visible light has been primarily employed in existing demonstrations. In this paper, we demonstrate a new plasmonic platform based on nanoporous gold disk (NPGD) array. Thanks to the highly tunable localized surface plasmon resonance of the NPGD array, microbubbles of controlled size can be generated by near-infrared (NIR) light. Using NIR light provides several key advantages over visible light in less interference with standard microscopy and fluorescence imaging, preventing fluorescence photobleaching, less susceptible to absorption and scattering in turbid biological media, and much reduced photochemistry, phototoxicity, and so forth. The large surface-to-volume ratio of NPGD further facilitates the heat transfer from these gold nanoheaters to the surroundings. While the microbubble is formed, the surrounding liquid circulates and direct microparticles randomly dispersed in the liquid to the bottom NPGD surface, which can be made to yield a unique collection of 3D hollow dome microstructures with bubbles larger than 5 μm. Such capability can also be employed in concentrating suspended colloidal nanoparticles at desirable sites and with the preferred configuration enhancing the sensor performance. Specifically, the interaction among concentrated nanoparticles and their interactions with the underlying substrate have been investigated for the first time. These collections have been characterized using optical microscopy, scanning electron microscopy, hyperspectral localized surface plasmon resonance imaging, and hyperspectral Raman imaging. In addition to various micro- and nanoparticles, the plasmonic microbubbles are also shown to collect biological cells and extracellular nanovesicles such as exosomes. By using a spatial light modulator to project the laser in arbitrary patterns, parallel concentrating can be achieved to fabricate an array of clusters.
在液体环境中通过激光产生的等离子体微泡对微米和纳米颗粒进行定向浓缩是一项新兴技术。在现有的演示中，为了实现有效加热，主要使用了可见光。在本文中，我们展示了一种基于纳米多孔金盘（NPGD）阵列的新型等离子体平台。由于NPGD阵列具有高度可调的局域表面等离子体共振特性，近红外（NIR）光可以产生尺寸可控的微泡。与可见光相比，使用近红外光具有几个关键优势，包括对标准显微镜和荧光成像的干扰较小、防止荧光光漂白、在浑浊的生物介质中不易被吸收和散射，以及大大降低光化学、光毒性等。NPGD的大表面积与体积比进一步促进了这些金纳米加热器向周围环境的热传递。当微泡形成时，周围的液体循环并将随机分散在液体中的微粒引导至底部的NPGD表面，从而可以形成独特的3D中空穹顶微结构集合，其中的气泡大于5μm。这种能力还可用于在理想位置浓缩悬浮的胶体纳米颗粒，并通过优化配置提高传感器性能。具体而言，首次研究了浓缩纳米颗粒之间的相互作用及其与底层基底的相互作用。使用光学显微镜、扫描电子显微镜、高光谱局域表面等离子体共振成像和高光谱拉曼成像对这些集合进行了表征。除了各种微米和纳米颗粒外，等离子体微泡还被证明可以收集生物细胞和细胞外纳米囊泡，如外泌体。通过使用空间光调制器以任意图案投射激光，可以实现平行浓缩以制造簇阵列。
