Mid-infrared photothermal microscopy is a new chemical imaging technology in which a visible beam senses the photothermal effect induced by a pulsed infrared laser. This technology provides infrared spectroscopic information at submicrometer spatial resolution and enables infrared spectroscopy and imaging of living cells and organisms. Yet, current mid-infrared photothermal imaging sensitivity suffers from a weak dependence of scattering on the temperature, and the image quality is vulnerable to the speckles caused by scattering. Here, we present a novel version of mid-infrared photothermal microscopy in which thermosensitive fluorescent probes are harnessed to sense the mid-infrared photothermal effect. The fluorescence intensity can be modulated at the level of 1% per Kelvin, which is 100 times larger than the modulation of scattering intensity. In addition, fluorescence emission is free of interference, thus much improving the image quality. Moreover, fluorophores can target specific organelles or biomolecules, thus augmenting the specificity of photothermal imaging. Spectral fidelity is confirmed through fingerprinting a single bacterium. Finally, the photobleaching issue is successfully addressed through the development of a wide-field fluorescence-detected mid-infrared photothermal microscope which allows video rate bond-selective imaging of biological specimens.
Last. Ji-Xin Cheng(BU: Boston University)H-Index: 83
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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 u...
Last. Ji-Xin Cheng(BU: Boston University)H-Index: 83
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We report a confocal interferometric mid-infrared photothermal (MIP) microscope for ultra-sensitive and spatially resolved chemical imaging of individual viruses. The interferometric scattering principle is applied to detect the very weak photothermal signal induced by infrared absorption of chemical bonds. Spectroscopic MIP detection of single vesicular stomatitis viruses (VSVs) and poxviruses is demonstrated. The single virus spectra show high consistency within the same virus type. The domina...
#2Xiaojie Li(CAS: Chinese Academy of Sciences)H-Index: 2
Last. Ji-Xin Cheng(BU: Boston University)H-Index: 83
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We report rapid and sensitive phenotyping of bacterial response to antibiotic treatment at single-cell resolution by a Raman-integrated optical mid-infrared photothermal (MIP) microscope. The MIP microscope successfully detected biochemical changes of bacteria in specific to the acting mechanism of erythromycin with 1 h incubation. Compared to Raman spectroscopy, MIP spectroscopy showed a much larger signal-to-noise ratio at the fingerprint region at an acquisition speed as fast as 1 s per spect...
#1Jiajun Du(California Institute of Technology)H-Index: 2
#2Yapeng Su(California Institute of Technology)H-Index: 12
Last. Lu Wei(California Institute of Technology)H-Index: 19
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Non-invasively probing metabolites within single live cells is highly desired but challenging. Here we utilize Raman spectro-microscopy for spatial mapping of metabolites within single cells, with the specific goal of identifying druggable metabolic susceptibilities from a series of patient-derived melanoma cell lines. Each cell line represents a different characteristic level of cancer cell de-differentiation. First, with Raman spectroscopy, followed by stimulated Raman scattering (SRS) microsc...
#1Agnieszka Banas(NUS: National University of Singapore)H-Index: 11
#2Krzysztof Banas(NUS: National University of Singapore)H-Index: 11
Last. Mark B. H. Breese(NUS: National University of Singapore)H-Index: 34
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As we live today under a constant threat of global terrorism, effective detection of highly energetic materials is one of the critical procedures needed at a variety of locations including airports...
Last. Masaru Kuno(ND: University of Notre Dame)H-Index: 55
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Infrared photothermal heterodyne imaging (IR-PHI) is an ultrasensitive technique for achieving super-resolution, infrared imaging throughout the mid-infrared “fingerprint” spectral region ( 2.5 – ...
Last. Takuro Ideguchi(UTokyo: University of Tokyo)H-Index: 16
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Label-free optical imaging is valuable in biology and medicine because of its non-destructive nature. Quantitative phase imaging (QPI) and molecular vibrational imaging (MVI) are the two most successful label-free methods, providing morphological and biochemical information, respectively. These techniques have enabled numerous applications as they have matured over the past few decades; however, their label-free contrasts are inherently complementary and difficult to integrate due to their relia...
Last. Isao Noda(UD: University of Delaware)H-Index: 69
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Abstract Optical photothermal infrared (O-PTIR) and Raman spectroscopy and imaging was used to explore the spatial distributions of molecular constituents of a laminate sample consisting of the bioplastics, polyhydroxyalkanoate (PHA) and polylactic acid (PLA), near the interfacial boundary. Highly spatially resolved simultaneous IR and Raman spectra were sequentially collected at 100 nm increments along a line traversing the interface. The set of spectra were subjected to 2D-COS analysis to extr...
#1Martin Schnell(UIUC: University of Illinois at Urbana–Champaign)H-Index: 17
#2Shachi Mittal(UIUC: University of Illinois at Urbana–Champaign)H-Index: 8
Last. Rohit Bhargava(UIUC: University of Illinois at Urbana–Champaign)H-Index: 48
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Optical microscopy for biomedical samples requires expertise in staining to visualize structure and composition. Midinfrared (mid-IR) spectroscopic imaging offers label-free molecular recording and virtual staining by probing fundamental vibrational modes of molecular components. This quantitative signal can be combined with machine learning to enable microscopy in diverse fields from cancer diagnoses to forensics. However, absorption of IR light by common optical imaging components makes mid-IR...
Loss of memory during Alzheimer's disease (AD), a fatal neurodegenerative disorder, is associated with neuronal loss and the aggregation of amyloid proteins into neurotoxic β‐sheet enriched structures. However, the mechanism of amyloid protein aggregation is still not well understood due to many challenges when studying the endogenous amyloid structures in neurons or in brain tissue. Available methods either require chemical processing of the sample or may affect the amyloid protein structure it...
Last. Michel Orrit(LEI: Leiden University)H-Index: 61
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Circular dichroism (CD) is the property of chiral nanoobjects to absorb circularly polarized light of either handedness to different extents. Photothermal microscopy enables the detection of CD signals with high sensitivity and provides a direct absorptive response of the samples under study. To achieve CD measurements at the single-particle level, one must reduce such artifacts as leakage of linear dichroism (LD) and residual intensity modulation. We have simulated our setup with a simple model...
