Bond-selective imaging by optically sensing the mid-infrared photothermal effect

Mid-infrared (IR) spectroscopic imaging using inherent vibrational contrast has been broadly used as a powerful analytical tool for sample identification and characterization. However, the low spatial resolution and large water absorption associated with the long IR wavelengths hinder its applications to study subcellular features in living systems. Recently developed mid-infrared photothermal (MIP) microscopy overcomes these limitations by probing the IR absorption–induced photothermal effect using a visible light. MIP microscopy yields submicrometer spatial resolution with high spectral fidelity and reduced water background. In this review, we categorize different photothermal contrast mechanisms and discuss instrumentations for scanning and widefield MIP microscope configurations. We highlight a broad range of applications from life science to materials. We further provide future perspective and potential venues in MIP microscopy field.

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Ultrafast chemical imaging by widefield photothermal sensing of infrared absorption

Science Advances ◽

10.1126/sciadv.aav7127 ◽

2019 ◽

Vol 5 (7) ◽

pp. eaav7127 ◽

Cited By ~ 9

Author(s):

Yeran Bai ◽

Delong Zhang ◽

Lu Lan ◽

Yimin Huang ◽

Kerry Maize ◽

...

Keyword(s):

Spatial Resolution ◽

High Throughput ◽

Chemical Imaging ◽

Photothermal Effect ◽

Nanometer Scale ◽

Light Pulses ◽

Spectral Fidelity ◽

Speed Up ◽

Lock In

Infrared (IR) imaging has become a viable tool for visualizing various chemical bonds in a specimen. The performance, however, is limited in terms of spatial resolution and imaging speed. Here, instead of measuring the loss of the IR beam, we use a pulsed visible light for high-throughput, widefield sensing of the transient photothermal effect induced by absorption of single mid-IR pulses. To extract these transient signals, we built a virtual lock-in camera synchronized to the visible probe and IR light pulses with precisely controlled delays, allowing submicrosecond temporal resolution determined by the probe pulse width. Our widefield photothermal sensing microscope enabled chemical imaging at a speed up to 1250 frames/s, with high spectral fidelity, while offering submicrometer spatial resolution. With the capability of imaging living cells and nanometer-scale polymer films, widefield photothermal microscopy opens a new way for high-throughput characterization of biological and material specimens.

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Depth-resolved mid-infrared photothermal imaging of living cells and organisms with submicrometer spatial resolution

Science Advances ◽

10.1126/sciadv.1600521 ◽

2016 ◽

Vol 2 (9) ◽

pp. e1600521 ◽

Cited By ~ 73

Author(s):

Delong Zhang ◽

Chen Li ◽

Chi Zhang ◽

Mikhail N. Slipchenko ◽

Gregory Eakins ◽

...

Keyword(s):

Spatial Resolution ◽

Single Cells ◽

Chemical Imaging ◽

Detection Sensitivity ◽

Living Systems ◽

Live Cells ◽

Photothermal Effect ◽

Label Free ◽

Infrared Microscopy ◽

Mid Infrared

Chemical contrast has long been sought for label-free visualization of biomolecules and materials in complex living systems. Although infrared spectroscopic imaging has come a long way in this direction, it is thus far only applicable to dried tissues because of the strong infrared absorption by water. It also suffers from low spatial resolution due to long wavelengths and lacks optical sectioning capabilities. We overcome these limitations through sensing vibrational absorption–induced photothermal effect by a visible laser beam. Our mid-infrared photothermal (MIP) approach reached 10 μM detection sensitivity and submicrometer lateral spatial resolution. This performance has exceeded the diffraction limit of infrared microscopy and allowed label-free three-dimensional chemical imaging of live cells and organisms. Distributions of endogenous lipid and exogenous drug inside single cells were visualized. We further demonstrated in vivo MIP imaging of lipids and proteins inCaenorhabditis elegans. The reported MIP imaging technology promises broad applications from monitoring metabolic activities to high-resolution mapping of drug molecules in living systems, which are beyond the reach of current infrared microscopy.

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Time lapse synchrotron IR chemical imaging for observing the acclimation of a single algal cell to CO2 treatment

Scientific Reports ◽

10.1038/s41598-021-92657-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ghazal Azarfar ◽

Ebrahim Aboualizadeh ◽

Simona Ratti ◽

Camilla Olivieri ◽

Alessandra Norici ◽

...

Keyword(s):

Algal Cell ◽

Principal Component ◽

External Perturbation ◽

Time Lapse ◽

Chemical Imaging ◽

Hyperspectral Data ◽

Aqueous Environment ◽

Ir Absorption ◽

Imaging Data ◽

Mid Infrared

AbstractAlgae are the main primary producers in aquatic environments and therefore of fundamental importance for the global ecosystem. Mid-infrared (IR) microspectroscopy is a non-invasive tool that allows in principle studying chemical composition on a single-cell level. For a long time, however, mid-infrared (IR) imaging of living algal cells in an aqueous environment has been a challenge due to the strong IR absorption of water. In this study, we employed multi-beam synchrotron radiation to measure time-resolved IR hyperspectral images of individual Thalassiosira weissflogii cells in water in the course of acclimation to an abrupt change of CO2 availability (from 390 to 5000 ppm and vice versa) over 75 min. We used a previously developed algorithm to correct sinusoidal interference fringes from IR hyperspectral imaging data. After preprocessing and fringe correction of the hyperspectral data, principal component analysis (PCA) was performed to assess the spatial distribution of organic pools within the algal cells. Through the analysis of 200,000 spectra, we were able to identify compositional modifications associated with CO2 treatment. PCA revealed changes in the carbohydrate pool (1200–950 cm$$^{-1}$$ - 1 ), lipids (1740, 2852, 2922 cm$$^{-1}$$ - 1 ), and nucleic acid (1160 and 1201 cm$$^{-1}$$ - 1 ) as the major response of exposure to elevated CO2 concentrations. Our results show a local metabolism response to this external perturbation.

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Performance and applications of a mid-infrared step-scan FT-IR spectroscopic imaging system

10.1117/12.310555 ◽

1998 ◽

Cited By ~ 1

Author(s):

Norman A. Wright ◽

Richard A. Crocombe ◽

David L. Drapcho

Keyword(s):

Imaging System ◽

Spectroscopic Imaging ◽

Mid Infrared ◽

Ft Ir ◽

Ir Spectroscopic

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Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

Review of Scientific Instruments ◽

10.1063/1.4954405 ◽

2016 ◽

Vol 87 (6) ◽

pp. 063119 ◽

Cited By ~ 22

Author(s):

Mbaye Faye ◽

Michel Bordessoule ◽

Brahim Kanouté ◽

Jean-Blaise Brubach ◽

Pascale Roy ◽

...

Keyword(s):

Synchrotron Radiation ◽

Spatial Resolution ◽

Infrared Detector ◽

Mid Infrared ◽

Radiation Use

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Conductivity Mapping in Graphene through Scattering-Type Scanning Near-Field Optical Microscopy in the Mid-Infrared and Terahertz Spectral Region with 25nm Spatial Resolution

ECS Meeting Abstracts ◽

10.1149/ma2018-01/10/872 ◽

2018 ◽

Keyword(s):

Optical Microscopy ◽

Spatial Resolution ◽

Spectral Region ◽

Near Field ◽

Mid Infrared

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Fusing China GF-5 Hyperspectral Data with GF-1, GF-2 and Sentinel-2A Multispectral Data: Which Methods Should Be Used?

Remote Sensing ◽

10.3390/rs12050882 ◽

2020 ◽

Vol 12 (5) ◽

pp. 882 ◽

Cited By ~ 3

Author(s):

Kai Ren ◽

Weiwei Sun ◽

Xiangchao Meng ◽

Gang Yang ◽

Qian Du

Keyword(s):

Spatial Resolution ◽

Comprehensive Evaluation ◽

Evaluation Study ◽

Hyperspectral Data ◽

Modulation Transfer ◽

Multispectral Data ◽

Spectral Bands ◽

Spectral Fidelity ◽

Fusion Methods ◽

Sentinel 2A

The China GaoFen-5 (GF-5) satellite sensor, which was launched in 2018, collects hyperspectral data with 330 spectral bands, a 30 m spatial resolution, and 60 km swath width. Its competitive advantages compared to other on-orbit or planned sensors are its number of bands, spectral resolution, and swath width. Unfortunately, its applications may be undermined by its relatively low spatial resolution. Therefore, the data fusion of GF-5 with high spatial resolution multispectral data is required to further enhance its spatial resolution while preserving its spectral fidelity. This paper conducted a comprehensive evaluation study of fusing GF-5 hyperspectral data with three typical multispectral data sources (i.e., GF-1, GF-2 and Sentinel-2A (S2A)), based on quantitative metrics, classification accuracy, and computational efficiency. Datasets on three study areas of China were utilized to design numerous experiments, and the performances of nine state-of-the-art fusion methods were compared. Experimental results show that LANARAS (this method was proposed by lanaras et al.), Adaptive Gram–Schmidt (GSA), and modulation transfer function (MTF)-generalized Laplacian pyramid (GLP) methods are more suitable for fusing GF-5 with GF-1 data, MTF-GLP and GSA methods are recommended for fusing GF-5 with GF-2 data, and GSA and smoothing filtered-based intensity modulation (SFIM) can be used to fuse GF-5 with S2A data.

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