Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging

Pump-probe excitation of fluorophores has been shown to overcome the limitations of conventional multiwavelength imaging and linear unmixing approaches by providing fluorophore-specific contrast whilst eliminating the dominant background signal of endogenous chromophores. In this study, methods for...

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Main Authors: Farzin Ghane Golmohamadi, Amna Mehmood, Hoang Trong Phan, Franz-Josef Schmitt, Jan Laufer
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Photoacoustics
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Online Access:http://www.sciencedirect.com/science/article/pii/S2213597925000618
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author Farzin Ghane Golmohamadi
Amna Mehmood
Hoang Trong Phan
Franz-Josef Schmitt
Jan Laufer
author_facet Farzin Ghane Golmohamadi
Amna Mehmood
Hoang Trong Phan
Franz-Josef Schmitt
Jan Laufer
author_sort Farzin Ghane Golmohamadi
collection DOAJ
description Pump-probe excitation of fluorophores has been shown to overcome the limitations of conventional multiwavelength imaging and linear unmixing approaches by providing fluorophore-specific contrast whilst eliminating the dominant background signal of endogenous chromophores. In this study, methods for generating pump-probe signals and images are investigated that rely on changing 1) the pump wavelength whilst keeping the probe wavelength fixed, 2) the probe wavelength whilst keeping the pump wavelength fixed, and 3) the time delay between the pump and probe pulse. Time-resolved PA signals were generated in purified solutions of genetically expressed red fluorescent proteins Katushka, mNeptune, and mCardinal in a cuvette. Spectra of the difference signal amplitude were found to correlate with the absorption and emission spectra. The difference signal plotted as a function of time delay also showed characteristic features for each protein. To demonstrate the capability of multiplexed imaging, the spatial distributions of Katushka and mNeptune were recovered from 2D difference images of a phantom. This study demonstrates that methods based on pump-probe excitation can be used to probe the photophysical properties of fluorophores. By detecting changes in these properties due to a stimulant, such as pH, the methods may find application in biosensing of the cellular microenvironment.
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spelling doaj-art-2be7ab6a0600463a981bfa727c5f046e2025-08-20T03:24:13ZengElsevierPhotoacoustics2213-59792025-08-014410073810.1016/j.pacs.2025.100738Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imagingFarzin Ghane Golmohamadi0Amna Mehmood1Hoang Trong Phan2Franz-Josef Schmitt3Jan Laufer4Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle (Saale) 06120, GermanyInstitut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle (Saale) 06120, GermanyInstitut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle (Saale) 06120, GermanyInstitut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle (Saale) 06120, GermanyCorresponding author.; Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle (Saale) 06120, GermanyPump-probe excitation of fluorophores has been shown to overcome the limitations of conventional multiwavelength imaging and linear unmixing approaches by providing fluorophore-specific contrast whilst eliminating the dominant background signal of endogenous chromophores. In this study, methods for generating pump-probe signals and images are investigated that rely on changing 1) the pump wavelength whilst keeping the probe wavelength fixed, 2) the probe wavelength whilst keeping the pump wavelength fixed, and 3) the time delay between the pump and probe pulse. Time-resolved PA signals were generated in purified solutions of genetically expressed red fluorescent proteins Katushka, mNeptune, and mCardinal in a cuvette. Spectra of the difference signal amplitude were found to correlate with the absorption and emission spectra. The difference signal plotted as a function of time delay also showed characteristic features for each protein. To demonstrate the capability of multiplexed imaging, the spatial distributions of Katushka and mNeptune were recovered from 2D difference images of a phantom. This study demonstrates that methods based on pump-probe excitation can be used to probe the photophysical properties of fluorophores. By detecting changes in these properties due to a stimulant, such as pH, the methods may find application in biosensing of the cellular microenvironment.http://www.sciencedirect.com/science/article/pii/S2213597925000618Molecular imagingPhotoacoustic imagingPump-probe excitationFluorescent protein
spellingShingle Farzin Ghane Golmohamadi
Amna Mehmood
Hoang Trong Phan
Franz-Josef Schmitt
Jan Laufer
Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging
Photoacoustics
Molecular imaging
Photoacoustic imaging
Pump-probe excitation
Fluorescent protein
title Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging
title_full Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging
title_fullStr Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging
title_full_unstemmed Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging
title_short Probing the photophysical properties of fluorescent proteins using photoacoustic pump-probe spectroscopy and imaging
title_sort probing the photophysical properties of fluorescent proteins using photoacoustic pump probe spectroscopy and imaging
topic Molecular imaging
Photoacoustic imaging
Pump-probe excitation
Fluorescent protein
url http://www.sciencedirect.com/science/article/pii/S2213597925000618
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