Video-rate Mid-infrared Photothermal Imaging by Single Pulse Photothermal Detection per Pixel

Yin, Jiaze; Zhang, Meng; Tan, Yuying; Guo, Zhongyue; He, Hongjian; Lan, Lu; Cheng, Ji‐Xin

doi:10.1101/2023.02.27.530116

Cited by 6 publications

(6 citation statements)

References 30 publications

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“…To address this limitation, a recently developed laser scan OPTIR microscope detects the transient photothermal signal induced by a single IR pulse through rapid digitization. 36 As a result, this new approach achieves significantly enhanced imaging speed-three orders of magnitude faster-across a large field of view.…”

Section: Discussionmentioning

confidence: 99%

High resolution and fast chemical imaging using widefield optical photothermal infrared microscope

Adak,

Raveendran,

Popp

et al. 2024

Biomedical Spectroscopy, Microscopy, and Imaging III

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Label-free infrared (IR) imaging reveals chemical bonds in specimens, but its limitations include a spatial resolution of approximately 5 µm. The advent of optical photothermal infrared (OPTIR) microscopy extends molecular fingerprint imaging by one order of magnitude near 500 nm. However, traditional scanning OPTIR faces a challenge of imaging speed. To improve speed and throughput, we employ pulsed visible probe light for widefield detection of transient photothermal responses induced by mid-infrared pulses. Our time-gated camera technique achieves sub-microsecond temporal resolution. We successfully imaged polystyrene beads, submicron SU8 polymer etchings, and mouse brain tissue samples using our widefield OPTIR microscope. The system excels in probe-dependent temporal and submicron spatial resolution, operating at 100 Hz over a 50 µm diameter field of view, while maintaining reasonable spectral fidelity. This enhanced widefield OPTIR microscopy promises rapid, label-free chemical imaging for biological samples and high-throughput screening applications.

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Section: Discussionmentioning

confidence: 99%

High resolution and fast chemical imaging using widefield optical photothermal infrared microscope

Adak,

Raveendran,

Popp

et al. 2024

Biomedical Spectroscopy, Microscopy, and Imaging III

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“…In the future, through continued advancement in MIP instrumentation (106), it should be feasible to add a temporal dimension to MIP applications for structural kinetics studies in cells. Lastly, MIP applications could also be extended to visualize other biomolecules, such as lipids and RNAs (107, 108), using their respective characteristic infrared absorption peaks, and enabling future applications where imaging of this rich chemical complexity could be acquired in real time.…”

Section: Discussionmentioning

confidence: 99%

Nanoscale Structural Mapping of Protein Aggregates in Live Cells Modeling Huntington’s Disease

Guo,

Chiesa,

Yin

et al. 2023

Preprint

Self Cite

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Protein aggregation, in the form of amyloid fibrils, is intimately correlated with many neurodegenerative diseases. Despite recent advances in structural biology, it remains challenging to acquire structural information of proteins in live cells. Tagging with fluorescent proteins, like green fluorescent protein (GFP), is routinely used for protein visualization. Yet, this method alone cannot provide detailed structural information on the protein system of interest, and tagging proteins has the potential to perturb native structure and function. Here, by fluorescence-detected as well as label-free scattering-based mid-infrared photothermal (MIP) microscopy, we demonstrate nanoscale mapping of secondary structure of protein aggregates in a yeast model of Huntington’s disease. We first used GFP as a highly sensitive photothermal reporter to validate β-sheet enrichment in huntingtin (htt) protein aggregates. We then obtained label-free structural maps of protein aggregates. Our data showed that the fluorescent protein tag indeed perturbed the secondary structure of the aggregate, evident by a spectral shift. Live cell MIP spectroscopy further revealed the fine spatial distribution of structurally distinct components in protein aggregates, featuring a 246-nm diameter core highly enriched in β-sheet surrounded by a ɑ-helix-rich shell. Interestingly, this structural partition exists only in presence of the [RNQ+] prion, a prion that acts to facilitate the formation of other amyloid prions. Indeed, when htt is induced to aggregate in the absence of this prion ([rnq-] state), it forms non-toxic amyloid aggregates exclusively. These results showcase the potential of MIP for unveiling detailed and subtle structural information on protein systems in live cells.SignificanceProtein aggregation is a hallmark of neurodegenerative diseases, such as Huntington’s Disease. Understanding the nature of neurotoxic aggregates could lead to better therapeutic approaches. The limited progress in this direction is partly due to the lack of tools for extracting structural information in the physiological context of the aggregates. Here, we report a photothermally detected mid-infrared micro-spectroscopy technique able to dissect the secondary structure of aggregates of the huntingtin protein in live cells. We describe for the first time a nanoscale partition of secondary structures between β-rich core and ɑ-rich shell of the aggregates. This work demonstrates the potential of mid-infrared photothermal microscopy for structural and functional mapping of proteins in live cells.

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“…Mid-infrared (MIR) spectroscopy plays a crucial role in biological ( 1 , 2 ) and materials research ( 3 ), pharmaceutical sciences ( 4 ), molecular dynamics ( 5 ), art conservation ( 6 ), and environmental monitoring ( 7 , 8 ) as a vital instrument for investigating the structure of substances. The most common method of analyzing MIR spectra is Fourier transform infrared (FTIR) spectroscopy ( 9 – 11 ).…”

Section: Introductionmentioning

confidence: 99%

Mid-infrared single-photon upconversion spectroscopy enabled by nonlocal wavelength-to-time mapping

Cai,

Chen,

Dorfman

et al. 2024

Sci. Adv.

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Ultrasensitive spectroscopy is an essential component in mid-infrared (MIR) technology. However, the drawbacks of MIR detectors pose challenges to robust MIR spectroscopy at the single-photon level. We propose an MIR single-photon frequency upconversion spectroscopy nonlocally mapping the MIR information to the time domain. Broadband MIR photons from spontaneous parametric downconversion are frequency-upconverted to the near-infrared band with quantum correlation preservation. Via the group delay of fiber, the MIR spectral information within a 1.18-micrometer bandwidth of 2.76 to 3.94 micrometers is then successfully projected to arrival times of correlated photon pairs. Under the conditions of 6.4 × 10 6 photons per second illumination, the transmission spectra of polymers with single-photon sensitivity are demonstrated using single-pixel detectors. The developed approach circumvents scanning and frequency selection instability, which stands out for its inherent compatibility for evolving environments and scalability for various wavelengths. Because of its high sensitivity and robustness, characterization of biochemical samples and weak measurement of quantum systems are possible to foresee.

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Video-rate Mid-infrared Photothermal Imaging by Single Pulse Photothermal Detection per Pixel

Cited by 6 publications

References 30 publications

High resolution and fast chemical imaging using widefield optical photothermal infrared microscope

High resolution and fast chemical imaging using widefield optical photothermal infrared microscope

Nanoscale Structural Mapping of Protein Aggregates in Live Cells Modeling Huntington’s Disease

Mid-infrared single-photon upconversion spectroscopy enabled by nonlocal wavelength-to-time mapping

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