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2021
Zong, Haonan; Yurdakul, Celalettin; Bai, Yeran; Zhang, Meng; Ünlü, M. Selim; Cheng, Ji-Xin
Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering Journal Article
In: ACS Photonics Article ASAP, vol. 8, iss. 11, pp. 3323, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokey,
title = {Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering},
author = {Haonan Zong and Celalettin Yurdakul and Yeran Bai and Meng Zhang and M. Selim Ünlü and Ji-Xin Cheng},
url = {https://arxiv.org/pdf/2104.06247},
doi = {https://doi.org/10.1021/acsphotonics.1c01197},
year = {2021},
date = {2021-10-14},
urldate = {2021-10-14},
journal = {ACS Photonics Article ASAP},
volume = {8},
issue = {11},
pages = {3323},
abstract = {Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.
Zong, Haonan; Yurdakul, Celalettin; Bai, Yeran; Zhang, Meng; Ünlü, M. Selim; Cheng, Ji-Xin
Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering Journal Article
In: ACS Photonics Article ASAP, vol. 8, iss. 11, pp. 3323, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokeyf,
title = {Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering},
author = {Haonan Zong and Celalettin Yurdakul and Yeran Bai and Meng Zhang and M. Selim Ünlü and Ji-Xin Cheng},
url = {https://arxiv.org/pdf/2104.06247},
doi = {https://doi.org/10.1021/acsphotonics.1c01197},
year = {2021},
date = {2021-10-14},
urldate = {2021-10-14},
journal = {ACS Photonics Article ASAP},
volume = {8},
issue = {11},
pages = {3323},
abstract = {Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.
Yurdakul, Celalettin; Zong, Haonan; Bai, Yeran; Cheng, Ji-Xin; Ünlü, M Selim
Bond-selective interferometric scattering microscopy Journal Article
In: Journal of Physics D: Applied Physics, vol. 54, iss. 36, pp. 364002, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokey,
title = {Bond-selective interferometric scattering microscopy},
author = {Celalettin Yurdakul and Haonan Zong and Yeran Bai and Ji-Xin Cheng and M Selim Ünlü},
url = {https://arxiv.org/pdf/2106.02931},
doi = {https://doi.org/10.1088/1361-6463/ac0b0d},
year = {2021},
date = {2021-06-25},
urldate = {2021-06-25},
journal = {Journal of Physics D: Applied Physics},
volume = {54},
issue = {36},
pages = {364002},
abstract = {Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.
Yurdakul, Celalettin; Zong, Haonan; Bai, Yeran; Cheng, Ji-Xin; Ünlü, M Selim
Bond-selective interferometric scattering microscopy Journal Article
In: Journal of Physics D: Applied Physics, vol. 54, iss. 36, pp. 364002, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokeyi,
title = {Bond-selective interferometric scattering microscopy},
author = {Celalettin Yurdakul and Haonan Zong and Yeran Bai and Ji-Xin Cheng and M Selim Ünlü},
url = {https://arxiv.org/pdf/2106.02931},
doi = {https://doi.org/10.1088/1361-6463/ac0b0d},
year = {2021},
date = {2021-06-25},
urldate = {2021-06-25},
journal = {Journal of Physics D: Applied Physics},
volume = {54},
issue = {36},
pages = {364002},
abstract = {Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.
1.
Zong, Haonan; Yurdakul, Celalettin; Bai, Yeran; Zhang, Meng; Ünlü, M. Selim; Cheng, Ji-Xin
Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering Journal Article
In: ACS Photonics Article ASAP, vol. 8, iss. 11, pp. 3323, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokey,
title = {Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering},
author = {Haonan Zong and Celalettin Yurdakul and Yeran Bai and Meng Zhang and M. Selim Ünlü and Ji-Xin Cheng},
url = {https://arxiv.org/pdf/2104.06247},
doi = {https://doi.org/10.1021/acsphotonics.1c01197},
year = {2021},
date = {2021-10-14},
urldate = {2021-10-14},
journal = {ACS Photonics Article ASAP},
volume = {8},
issue = {11},
pages = {3323},
abstract = {Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.
2.
Zong, Haonan; Yurdakul, Celalettin; Bai, Yeran; Zhang, Meng; Ünlü, M. Selim; Cheng, Ji-Xin
Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering Journal Article
In: ACS Photonics Article ASAP, vol. 8, iss. 11, pp. 3323, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokeyf,
title = {Background-Suppressed High-Throughput Mid-Infrared Photothermal Microscopy via Pupil Engineering},
author = {Haonan Zong and Celalettin Yurdakul and Yeran Bai and Meng Zhang and M. Selim Ünlü and Ji-Xin Cheng},
url = {https://arxiv.org/pdf/2104.06247},
doi = {https://doi.org/10.1021/acsphotonics.1c01197},
year = {2021},
date = {2021-10-14},
urldate = {2021-10-14},
journal = {ACS Photonics Article ASAP},
volume = {8},
issue = {11},
pages = {3323},
abstract = {Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Mid-infrared photothermal (MIP) microscopy has been a promising label-free chemical imaging technique for functional characterization of specimens owing to its enhanced spatial resolution and high specificity. Recently developed wide-field MIP imaging modalities have drastically improved speed and enabled high-throughput imaging of micron-scale subjects. However, the weakly scattered signal from subwavelength particles becomes indistinguishable from the shot-noise as a consequence of the strong background light, leading to limited sensitivity. Here, we demonstrate background-suppressed chemical fingerprinting at a single nanoparticle level by selectively attenuating the reflected light through pupil engineering in the collection path. Our technique provides over 3 orders of magnitude background suppression by quasi-darkfield illumination in the epi-configuration without sacrificing lateral resolution. We demonstrate 6-fold signal-to-background noise ratio improvement, allowing for simultaneous detection and discrimination of hundreds of nanoparticles across a field of view of 70 μm × 70 μm. A comprehensive theoretical framework for photothermal image formation is provided and experimentally validated with 300 and 500 nm PMMA beads. The versatility and utility of our technique are demonstrated via hyperspectral dark-field MIP imaging of S. aureus and E. coli bacteria and MIP imaging of subcellular lipid droplets inside C. albicans and cancer cells.
3.
Yurdakul, Celalettin; Zong, Haonan; Bai, Yeran; Cheng, Ji-Xin; Ünlü, M Selim
Bond-selective interferometric scattering microscopy Journal Article
In: Journal of Physics D: Applied Physics, vol. 54, iss. 36, pp. 364002, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokey,
title = {Bond-selective interferometric scattering microscopy},
author = {Celalettin Yurdakul and Haonan Zong and Yeran Bai and Ji-Xin Cheng and M Selim Ünlü},
url = {https://arxiv.org/pdf/2106.02931},
doi = {https://doi.org/10.1088/1361-6463/ac0b0d},
year = {2021},
date = {2021-06-25},
urldate = {2021-06-25},
journal = {Journal of Physics D: Applied Physics},
volume = {54},
issue = {36},
pages = {364002},
abstract = {Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.
4.
Yurdakul, Celalettin; Zong, Haonan; Bai, Yeran; Cheng, Ji-Xin; Ünlü, M Selim
Bond-selective interferometric scattering microscopy Journal Article
In: Journal of Physics D: Applied Physics, vol. 54, iss. 36, pp. 364002, 2021.
Abstract | Links | BibTeX | Tags: Bacteria
@article{nokeyi,
title = {Bond-selective interferometric scattering microscopy},
author = {Celalettin Yurdakul and Haonan Zong and Yeran Bai and Ji-Xin Cheng and M Selim Ünlü},
url = {https://arxiv.org/pdf/2106.02931},
doi = {https://doi.org/10.1088/1361-6463/ac0b0d},
year = {2021},
date = {2021-06-25},
urldate = {2021-06-25},
journal = {Journal of Physics D: Applied Physics},
volume = {54},
issue = {36},
pages = {364002},
abstract = {Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.},
keywords = {Bacteria},
pubstate = {published},
tppubtype = {article}
}
Interferometric scattering (iSCAT) microscopy has been a very promising technology for highly sensitive label-free imaging of a broad spectrum of biological nanoparticles from proteins to viruses in a high-throughput manner. Although it can reveal the specimen's size and shape information, the chemical composition is inaccessible in interferometric measurements. Infrared (IR) spectroscopic imaging provides chemical specificity based on inherent chemical bond vibrations of specimens but lacks the ability to image and resolve individual nanoparticles due to long IR wavelengths. Here, we describe a bond-selective iSCAT microscope where the mid-IR induced photothermal signal is detected by a visible beam in a wide-field common-path interferometry configuration. A thin film layered substrate is utilized to reduce the reflected light and provide a reference field for the interferometric detection of the weakly scattered field. A pulsed mid-IR laser is employed to modulate the interferometric signal. Subsequent demodulation via a virtual lock-in camera offers simultaneous chemical information about tens of micro- or nano-particles. The chemical contrast arises from a minute change in the particle's scattered field in consequence of the vibrational absorption at the target molecule. We characterize the system with sub-wavelength polymer beads and highlight biological applications by chemically imaging several microorganisms including Staphylococcus aureus, Escherichia coli, and Candida albicans. A theoretical framework is established to extend bond-selective iSCAT microscopy to a broad range of biological micro- and nano-particles.
