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Abstract：
Whispering-gallery-mode (WGM) resonators are powerful instruments for single-molecule sensing in biological and biochemical investigations. WGM sensors leveraged by plasmonic nanostructures, known as optoplasmonic sensors, provide sensitivity down to single atomic ions. In this article, we describe that the response of optoplasmonic sensors upon the attachment of single protein molecules strongly depends on the intensity of WGM. At low intensity, protein binding causes red shifts of WGM resonance wavelengths, known as the reactive sensing mechanism. By contrast, blue shifts are obtained at high intensities, which we explain as thermo-optoplasmonic (TOP) sensing, where molecules transform absorbed WGM radiation into heat. To support our conclusions, we experimentally investigated seven molecules and complexes; we observed blue shifts for dye molecules, amino acids, and anomalous absorption of enzymes in the near-infrared spectral region. As an example of an application, we propose a physical model of TOP sensing that can be used for the development of single-molecule absorption spectrometers.
摘要：
耳语画廊模式（WGM）谐振器是生物和生化研究中用于单分子传感的强大工具。利用等离子体纳米结构的WGM传感器，被称为光等离子体传感器，提供对单原子离子的灵敏度。在这篇文章中,我们描述了光等离子体传感器对单个蛋白质分子附着的响应强烈取决于WGM的强度。在低强度下,蛋白质结合引起WGM共振波长的红移，称为反应传感机制。相比之下,在高强度下获得蓝移，我们解释为热光等离子体(TOP)传感，分子将吸收的WGM辐射转化为热量。为了支持我们的结论,我们实验研究了七个分子和复合物；我们观察到染料分子的蓝移，氨基酸,和酶在近红外光谱区域的异常吸收。作为应用程序的示例，我们提出了TOP传感的物理模型，可用于开发单分子吸收光谱仪。
