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.
Original language | English |
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Pages (from-to) | 17534-17546 |
Number of pages | 13 |
Journal | ACS Nano |
Volume | 18 |
Issue number | 27 |
Early online date | 26 Jun 2024 |
DOIs | |
Publication status | Published - 9 Jul 2024 |
Externally published | Yes |
Funding
The authors acknowledge funding from UKRI Engineering and Physical Sciences Research Council [EP/T002875/1]. M.C.H. acknowledges funding from the UKRI Biotechnology and Biological Sciences Research Council-funded South West Biosciences Doctoral Training Partnership [BB/T008741/1].
Funders | Funder number |
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Engineering and Physical Sciences Research Council | EP/T002875/1 |
Engineering and Physical Sciences Research Council | |
UKRI CDT in Accountable, Responsible and Transparent AI | BB/T008741/1 |
Keywords
- absorption
- microresonator
- plasmon
- protein
- sensor
- tryptophan
ASJC Scopus subject areas
- General Materials Science
- General Engineering
- General Physics and Astronomy