151
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Liao CR, Rak M, Lund J, Unger M, Platt E, Albensi BC, Hirschmugl CJ, Gough KM. Synchrotron FTIR reveals lipid around and within amyloid plaques in transgenic mice and Alzheimer's disease brain. Analyst 2013; 138:3991-7. [PMID: 23586070 DOI: 10.1039/c3an00295k] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
While the basis of neuronal degeneration in Alzheimer's disease (AD) continues to be debated, the amyloid cascade hypothesis remains central. Amyloid plaques are a required pathological marker for post mortem diagnosis, and Aβ peptide is regarded by most as a critical trigger at the very least. We present spectrochemical image analysis of brain tissue sections obtained with the mid-infrared beamline IRENI (InfraRed ENvironmental Imaging, Synchrotron Radiation Center, U Wisconsin-Madison), where the pixel resolution of 0.54 × 0.54 µm(2) permits analysis at sub-cellular dimensions. Spectrochemical images of dense core plaque found in hippocampus and cortex sections of two transgenic mouse models of AD (TgCRND8 and 3×Tg) are compared with plaque images from a 91 year old apoE43 human AD case. Spectral analysis was done in conjunction with histochemical stains of serial sections. A lipid membrane-like spectral signature surrounded and infiltrated the dense core plaques in all cases. Remarkable compositional similarities in early stage plaques suggest similar routes to plaque formation, regardless of genetic predisposition or mammalian origin.
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Affiliation(s)
- Catherine R Liao
- Department of Chemistry, University of Manitoba, 360 Parker Building,144 Dysart Road, Winnipeg, Manitoba, Canada.
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152
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Opportunities for live cell FT-infrared imaging: macromolecule identification with 2D and 3D localization. Int J Mol Sci 2013; 14:22753-81. [PMID: 24256815 PMCID: PMC3856089 DOI: 10.3390/ijms141122753] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 10/31/2013] [Accepted: 11/01/2013] [Indexed: 12/22/2022] Open
Abstract
Infrared (IR) spectromicroscopy, or chemical imaging, is an evolving technique that is poised to make significant contributions in the fields of biology and medicine. Recent developments in sources, detectors, measurement techniques and speciman holders have now made diffraction-limited Fourier transform infrared (FTIR) imaging of cellular chemistry in living cells a reality. The availability of bright, broadband IR sources and large area, pixelated detectors facilitate live cell imaging, which requires rapid measurements using non-destructive probes. In this work, we review advances in the field of FTIR spectromicroscopy that have contributed to live-cell two and three-dimensional IR imaging, and discuss several key examples that highlight the utility of this technique for studying the structure and chemistry of living cells.
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153
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Pita I, Hendaoui N, Liu N, Kumbham M, Tofail SAM, Peremans A, Silien C. High resolution imaging with differential infrared absorption micro-spectroscopy. OPTICS EXPRESS 2013; 21:25632-25642. [PMID: 24216788 DOI: 10.1364/oe.21.025632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Although confocal infrared (IR) absorption micro-spectroscopy is well established for far-field chemical imaging, its scope remains restricted since diffraction limits the spatial resolution to values a little above half the radiation wavelength. Yet, the successful implementations of below-the-diffraction limit far-field fluorescence microscopies using saturated irradiation patterns for example for stimulated-emission depletion and saturated structured-illumination suggest the possibility of using a similar optical patterning strategy for infrared absorption mapping at high resolution. Simulations are used to show that the simple mapping of the difference in transmitted/reflected IR energy between a saturated vortex-shaped beam and a Gaussian reference with a confocal microscope affords the generation of high-resolution vibrational absorption images. On the basis of experimentally relevant parameters, the simulations of the differential absorption scheme reveal a spatial resolution better than a tenth of the wavelength for incident energies about a decade above the saturation threshold. The saturated structured illumination concepts are thus expected to be compatible with the establishment of point-like point-spread functions for measuring the absorbance of samples with a scanning confocal microscope recording the differential transmission/reflection.
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154
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Li Y, Su L, Shou C, Yu C, Deng J, Fang Y. Surface-enhanced molecular spectroscopy (SEMS) based on perfect-absorber metamaterials in the mid-infrared. Sci Rep 2013; 3:2865. [PMID: 24091778 PMCID: PMC3790207 DOI: 10.1038/srep02865] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 09/17/2013] [Indexed: 01/11/2023] Open
Abstract
Surface-enhanced infrared absorption spectroscopy has attracted increased attention for direct access to molecular vibrational fingerprints in the mid-infrared. Perfect-absorber metamaterials (PAMs) with multi-band spectral responses and significant enhancement of the local near-field intensity were developed to improve the intrinsic absorption cross sections of absorption spectrum to identify the vibrational spectra of biomolecules. To verify its performance, the proposed infrared PAM array was used to identify the molecular stretches of a Parylene C film. The resonant responses of the infrared PAMs were accurately tuned to the vibrational modes of the C = C target bonds. The vibrational stretches of the C = C moiety were observed and the auto-fluorescence mechanisms of the Parylene C film were monitored. The unique properties of the PAMs indicate that this approach is a promising strategy for surface-enhanced molecular absorption spectroscopy (SEMS) in the mid-infrared region and for the tracking of characteristic molecular vibrational modes.
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Affiliation(s)
- Yongqian Li
- Key Laboratory of Micro/Nano Systems for Aerospace of Ministry of Education, Northwestern Polytechnical University, Xi'an, China, 710072
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155
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Borisjuk L, Rolletschek H, Neuberger T. Nuclear magnetic resonance imaging of lipid in living plants. Prog Lipid Res 2013; 52:465-87. [DOI: 10.1016/j.plipres.2013.05.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Revised: 05/15/2013] [Accepted: 05/28/2013] [Indexed: 01/13/2023]
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156
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Glassford SE, Byrne B, Kazarian SG. Recent applications of ATR FTIR spectroscopy and imaging to proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2849-58. [PMID: 23928299 DOI: 10.1016/j.bbapap.2013.07.015] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/24/2013] [Accepted: 07/27/2013] [Indexed: 11/25/2022]
Abstract
Attenuated Total Reflection (ATR) Fourier Transform Infrared (FTIR) spectroscopy is a label-free, non-destructive analytical technique that can be used extensively to study a wide variety of different molecules in a range of different conditions. The aim of this review is to discuss and highlight the recent advances in the applications of ATR FTIR spectroscopic imaging to proteins. It briefly covers the basic principles of ATR FTIR spectroscopy and ATR FTIR spectroscopic imaging as well as their advantages to the study of proteins compared to other techniques and other forms of FTIR spectroscopy. It will then go on to examine the advances that have been made within the field over the last several years, particularly the use of ATR FTIR spectroscopy for the understanding and development of protein interaction with surfaces. Additionally, the growing potential of Surface Enhanced Infrared Spectroscopy (SEIRAS) within this area of applications will be discussed. The review includes the applications of ATR FTIR imaging to protein crystallisation and for high-throughput studies, highlighting the future potential of the technology within the field of protein structural studies and beyond.
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157
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Martin MC, Dabat-Blondeau C, Unger M, Sedlmair J, Parkinson DY, Bechtel HA, Illman B, Castro JM, Keiluweit M, Buschke D, Ogle B, Nasse MJ, Hirschmugl CJ. 3D spectral imaging with synchrotron Fourier transform infrared spectro-microtomography. Nat Methods 2013; 10:861-4. [PMID: 23913258 DOI: 10.1038/nmeth.2596] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 07/02/2013] [Indexed: 10/26/2022]
Abstract
We report Fourier transform infrared spectro-microtomography, a nondestructive three-dimensional imaging approach that reveals the distribution of distinctive chemical compositions throughout an intact biological or materials sample. The method combines mid-infrared absorption contrast with computed tomographic data acquisition and reconstruction to enhance chemical and morphological localization by determining a complete infrared spectrum for every voxel (millions of spectra determined per sample).
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Affiliation(s)
- Michael C Martin
- Advanced Light Source Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA.
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158
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Hackett MJ, Borondics F, Brown D, Hirschmugl C, Smith SE, Paterson PG, Nichol H, Pickering IJ, George GN. Subcellular biochemical investigation of purkinje neurons using synchrotron radiation fourier transform infrared spectroscopic imaging with a focal plane array detector. ACS Chem Neurosci 2013; 4:1071-80. [PMID: 23638613 DOI: 10.1021/cn4000346] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Coupling Fourier transform infrared spectroscopy with focal plane array detectors at synchrotron radiation sources (SR-FTIR-FPA) has provided a rapid method to simultaneously image numerous biochemical markers in situ at diffraction limited resolution. Since cells and nuclei are well resolved at this spatial resolution, a direct comparison can be made between FTIR functional group images and the histology of the same section. To allow histological analysis of the same section analyzed with infrared imaging, unfixed air-dried tissue sections are typically fixed (after infrared spectroscopic analysis is completed) via immersion fixation. This post fixation process is essential to allow histological staining of the tissue section. Although immersion fixation is a common practice in this filed, the initial rehydration of the dehydrated unfixed tissue can result in distortion of subcellular morphology and confound correlation between infrared images and histology. In this study, vapor fixation, a common choice in other research fields where postfixation of unfixed tissue sections is required, was employed in place of immersion fixation post spectroscopic analysis. This method provided more accurate histology with reduced distortions as the dehydrated tissue section is fixed in vapor rather than during rehydration in an aqueous fixation medium. With this approach, accurate correlation between infrared images and histology of the same section revealed that Purkinje neurons in the cerebellum are rich in cytosolic proteins and not depleted as once thought. In addition, we provide the first direct evidence of intracellular lactate within Purkinje neurons. This highlights the significant potential for future applications of SR-FTIR-FPA imaging to investigate cellular lactate under conditions of altered metabolic demand such as increased brain activity and hypoxia or ischemia.
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Affiliation(s)
- Mark J. Hackett
- Molecular and Environmental Sciences Group, Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon,
Saskatchewan S7N5E2, Canada
| | | | - Devin Brown
- Department of Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Rd, Saskatoon,
Saskatchewan S7N5E5, Canada
| | - Carol Hirschmugl
- Department of Physics, University of Wisconsin—Milwaukee, Milwaukee,
Wisconsin 53211, United States
| | - Shari E. Smith
- College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewn S7N5C9, Canada
| | - Phyllis G. Paterson
- College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewn S7N5C9, Canada
| | - Helen Nichol
- Department of Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Rd, Saskatoon,
Saskatchewan S7N5E5, Canada
| | - Ingrid J. Pickering
- Molecular and Environmental Sciences Group, Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon,
Saskatchewan S7N5E2, Canada
| | - Graham N. George
- Molecular and Environmental Sciences Group, Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon,
Saskatchewan S7N5E2, Canada
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159
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Marcott C, Lo M, Kjoller K, Domanov Y, Balooch G, Luengo GS. Nanoscale infrared (IR) spectroscopy and imaging of structural lipids in human stratum corneum using an atomic force microscope to directly detect absorbed light from a tunable IR laser source. Exp Dermatol 2013; 22:419-21. [PMID: 23651342 DOI: 10.1111/exd.12144] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2013] [Indexed: 11/27/2022]
Abstract
An atomic force microscope (AFM) and a tunable infrared (IR) laser source have been combined in a single instrument (AFM-IR) capable of producing ~200-nm spatial resolution IR spectra and absorption images. This new capability enables IR spectroscopic characterization of human stratum corneum at unprecendented levels. Samples of normal and delipidized stratum corneum were embedded, cross-sectioned and mounted on ZnSe prisms. A pulsed tunable IR laser source produces thermomechanical expansion upon absorption, which is detected through excitation of contact resonance modes in the AFM cantilever. In addition to reducing the total lipid content, the delipidization process damages the stratum corneum morphological structure. The delipidized stratum corneum shows substantially less long-chain CH2 -stretching IR absorption band intensity than normal skin. AFM-IR images that compare absorbances at 2930/cm (lipid) and 3290/cm (keratin) suggest that regions of higher lipid concentration are located at the perimeter of corneocytes in the normal stratum corneum.
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160
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Ling S, Qi Z, Knight DP, Huang Y, Huang L, Zhou H, Shao Z, Chen X. Insight into the structure of single Antheraea pernyi silkworm fibers using synchrotron FTIR microspectroscopy. Biomacromolecules 2013; 14:1885-92. [PMID: 23607809 DOI: 10.1021/bm400267m] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synchrotron FTIR (S-FTIR) microspectroscopy was used to monitor both protein secondary structures (conformations) and their orientations in single cocoon silk fibers of the Chinese Tussah silk moth ( Antheraea pernyi ). In addition, to understand further the relationship between structure and properties of single silk fibers, we studied the changes of orientation and content of different secondary structures in single A. pernyi silk fibers when subjected to different strains. The results showed that the content and orientation of β-sheet was almost unchanged for strains from 0 to 0.3. However, the orientation of α-helix and random coil improved progressively with increasing strain, with a parallel decrease in α-helix content and an increase in random coil. This clearly indicates that most of the deformation upon stretching of the single fiber is due to the change of orientation in the amorphous regions coupled with a conversion of some of the α-helix to random coil. These observations provide an explanation for the supercontraction behavior of certain animal silks and are likely to facilitate understanding and optimization of postdrawing used in the conjunction with the wet-spinning of silk fibers from regenerated silk solutions. Thus, our work demonstrates the power of S-FTIR microspectroscopy for studying biopolymers.
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Affiliation(s)
- Shengjie Ling
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University , Shanghai, 200433, People's Republic of China
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161
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Tobin MJ, Puskar L, Hasan J, Webb HK, Hirschmugl CJ, Nasse MJ, Gervinskas G, Juodkazis S, Watson GS, Watson JA, Crawford RJ, Ivanova EP. High-spatial-resolution mapping of superhydrophobic cicada wing surface chemistry using infrared microspectroscopy and infrared imaging at two synchrotron beamlines. JOURNAL OF SYNCHROTRON RADIATION 2013; 20:482-489. [PMID: 23592628 DOI: 10.1107/s0909049513004056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 02/09/2013] [Indexed: 06/02/2023]
Abstract
The wings of some insects, such as cicadae, have been reported to possess a number of interesting and unusual qualities such as superhydrophobicity, anisotropic wetting and antibacterial properties. Here, the chemical composition of the wings of the Clanger cicada (Psaltoda claripennis) were characterized using infrared (IR) microspectroscopy. In addition, the data generated from two separate synchrotron IR facilities, the Australian Synchrotron Infrared Microspectroscopy beamline (AS-IRM) and the Synchrotron Radiation Center (SRC), University of Wisconsin-Madison, IRENI beamline, were analysed and compared. Characteristic peaks in the IR spectra of the wings were assigned primarily to aliphatic hydrocarbon and amide functionalities, which were considered to be an indication of the presence of waxy and proteinaceous components, respectively, in good agreement with the literature. Chemical distribution maps showed that, while the protein component was homogeneously distributed, a significant degree of heterogeneity was observed in the distribution of the waxy component, which may contribute to the self-cleaning and aerodynamic properties of the cicada wing. When comparing the data generated from the two beamlines, it was determined that the SRC IRENI beamline was capable of producing higher-spatial-resolution distribution images in a shorter time than was achievable at the AS-IRM beamline, but that spectral noise levels per pixel were considerably lower on the AS-IRM beamline, resulting in more favourable data where the detection of weak absorbances is required. The data generated by the two complementary synchrotron IR methods on the chemical composition of cicada wings will be immensely useful in understanding their unusual properties with a view to reproducing their characteristics in, for example, industry applications.
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Affiliation(s)
- Mark J Tobin
- Infrared Microspectroscopy Beamline, Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, Australia.
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162
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Clemons C, Sedlmair J, Illman B, Ibach R, Hirschmugl C. Chemically imaging the effects of the addition of nanofibrillated cellulose on the distribution of poly(acrylic acid) in poly(vinyl alcohol). POLYMER 2013. [DOI: 10.1016/j.polymer.2013.02.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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163
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Mattson EC, Unger M, Manandhar B, Alavi Z, Hirschmugl CJ. Multi-beam Synchrotron FTIR Chemical Imaging: Impacts of Schwarzschild Objective and Spatial Oversampling on Spatial Resolution. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/425/14/142001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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164
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Stavitski E, Smith RJ, Bourassa MW, Acerbo AS, Carr GL, Miller LM. Dynamic full-field infrared imaging with multiple synchrotron beams. Anal Chem 2013; 85:3599-605. [PMID: 23458231 DOI: 10.1021/ac3033849] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Microspectroscopic imaging in the infrared (IR) spectral region allows for the examination of spatially resolved chemical composition on the microscale. More than a decade ago, it was demonstrated that diffraction-limited spatial resolution can be achieved when an apertured, single-pixel IR microscope is coupled to the high brightness of a synchrotron light source. Nowadays, many IR microscopes are equipped with multipixel Focal Plane Array (FPA) detectors, which dramatically improve data acquisition times for imaging large areas. Recently, progress been made toward efficiently coupling synchrotron IR beamlines to multipixel detectors, but they utilize expensive and highly customized optical schemes. Here we demonstrate the development and application of a simple optical configuration that can be implemented on most existing synchrotron IR beamlines to achieve full-field IR imaging with diffraction-limited spatial resolution. Specifically, the synchrotron radiation fan is extracted from the bending magnet and split into four beams that are combined on the sample, allowing it to fill a large section of the FPA. With this optical configuration, we are able to oversample an image by more than a factor of 2, even at the shortest wavelengths, making image restoration through deconvolution algorithms possible. High chemical sensitivity, rapid acquisition times, and superior signal-to-noise characteristics of the instrument are demonstrated. The unique characteristics of this setup enabled the real-time study of heterogeneous chemical dynamics with diffraction-limited spatial resolution for the first time.
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Affiliation(s)
- Eli Stavitski
- Photon Sciences Directorate, Brookhaven National Laboratory, Upton, New York 11973, United States
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165
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Vita N, Brubach JB, Hienerwadel R, Bremond N, Berthomieu D, Roy P, Berthomieu C. Electrochemically Induced Far-Infrared Difference Spectroscopy on Metalloproteins Using Advanced Synchrotron Technology. Anal Chem 2013; 85:2891-8. [DOI: 10.1021/ac303511g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Nicolas Vita
- Lab Interactions Protein Metal, Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Saint-Paul-lez-Durance,
F-13108, France
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
- Société Civile Synchrotron SOLEIL, L’Orme des Merisiers,
St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Jean-Blaise Brubach
- Société Civile Synchrotron SOLEIL, L’Orme des Merisiers,
St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Rainer Hienerwadel
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Lab Genet Biophys Plantes, Aix-Marseille Université, Marseille, F-13009,
France
- Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Marseille,
F-13009, France
| | - Nicolas Bremond
- Lab Interactions Protein Metal, Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Saint-Paul-lez-Durance,
F-13108, France
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
| | - Dorothée Berthomieu
- Institut Charles Gerhardt, MACS, UMR 5253 CNRS-ENSCM-UM1-UM2, 8, rue
de l’Ecole Normale, 34296 Montpellier Cedex 5, France
| | - Pascale Roy
- Société Civile Synchrotron SOLEIL, L’Orme des Merisiers,
St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Catherine Berthomieu
- Lab Interactions Protein Metal, Commissariat à l’Energie Atomique (CEA), DSV, IBEB, Saint-Paul-lez-Durance,
F-13108, France
- Centre National de la Recherche Scientifique, UMR Biol Veget et Microbiol
Environ, Saint-Paul-lez-Durance, F-13108, France
- Aix-Marseille Université, Saint-Paul-lez-Durance, F-13108, France
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166
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Lahiri B, Holland G, Centrone A. Chemical imaging beyond the diffraction limit: experimental validation of the PTIR technique. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:439-45. [PMID: 23034929 DOI: 10.1002/smll.201200788] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 08/10/2012] [Indexed: 05/05/2023]
Abstract
Photothermal induced resonance (PTIR) has recently attracted great interest for enabling chemical identification and imaging with nanoscale resolution. In this work, electron beam nanopatterned polymer samples are fabricated directly on 3D zinc selenide prisms and used to experimentally evaluate the PTIR lateral resolution, sensitivity and linearity. It is shown that PTIR lateral resolution for chemical imaging is comparable to the lateral resolution obtained in the atomic force microscopy height images, up to the smallest feature measured (100 nm). Spectra and chemical maps are produced from the thinnest sample analyzed (40 nm). More importantly, experiments show for the first time that the PTIR signal increases linearly with thickness for samples up to ≈ 1 μm (linearity limit); a necessary requirement towards the use of the PTIR technique for quantitative chemical analysis at the nanoscale. Finally, the analysis of thicker samples provides the first evidence that the previously developed PTIR signal generation theory is correct. It is believed that the findings of this work will foster nanotechnology development in disparate applications by proving the basis for quantitative chemical analysis with nanoscale resolution.
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Affiliation(s)
- Basudev Lahiri
- NIST, Center for Nanoscale Science and Technology, Gaithersburg, MD 20899, USA
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167
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Katzenmeyer AM, Aksyuk V, Centrone A. Nanoscale infrared spectroscopy: improving the spectral range of the photothermal induced resonance technique. Anal Chem 2013; 85:1972-9. [PMID: 23363013 DOI: 10.1021/ac303620y] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Photothermal induced resonance (PTIR) is a new technique which combines the chemical specificity of infrared (IR) spectroscopy with the lateral resolution of atomic force microscopy (AFM). PTIR requires a pulsed tunable laser for sample excitation and an AFM tip to measure the sample expansion induced by light absorption. The limited tunability of commonly available laser sources constrains the application of the PTIR technique to a portion of the IR spectrum. In this work, a broadly tunable pulsed laser relying on a difference frequency generation scheme in a GaSe crystal to emit light tunable from 1.55 μm to 16 μm (from 6450 cm(-1) to 625 cm(-1)) was interfaced with a commercial PTIR instrument. The result is a materials characterization platform capable of chemical imaging, in registry with atomic force images, with a spatial resolution that notably surpasses the light diffraction limit throughout the entire mid-IR spectral range. PTIR nanoscale spectra and images allow the identification of compositionally and optically similar yet distinct materials; organic, inorganic, and composite samples can be studied with this nanoscale analog of infrared spectroscopy, suggesting broad applicability. Additionally, we compare the results obtained with the two tunable lasers, which have different pulse lengths, to experimentally assess the recently developed theory of PTIR signal generation.
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Affiliation(s)
- Aaron M Katzenmeyer
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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168
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Felts JR, Cho H, Yu MF, Bergman LA, Vakakis AF, King WP. Atomic force microscope infrared spectroscopy on 15 nm scale polymer nanostructures. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:023709. [PMID: 23464220 DOI: 10.1063/1.4793229] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We measure the infrared spectra of polyethylene nanostructures of height 15 nm using atomic force microscope infrared spectroscopy (AFM-IR), which is about an order of magnitude improvement over state of the art. In AFM-IR, infrared light incident upon a sample induces photothermal expansion, which is measured by an AFM tip. The thermomechanical response of the sample-tip-cantilever system results in cantilever vibrations that vary in time and frequency. A time-frequency domain analysis of the cantilever vibration signal reveals how sample thermomechanical response and cantilever dynamics affect the AFM-IR signal. By appropriately filtering the cantilever vibration signal in both the time domain and the frequency domain, it is possible to measure infrared absorption spectra on polyethylene nanostructures as small as 15 nm.
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Affiliation(s)
- Jonathan R Felts
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
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169
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Miller LM, Bourassa MW, Smith RJ. FTIR spectroscopic imaging of protein aggregation in living cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2339-46. [PMID: 23357359 DOI: 10.1016/j.bbamem.2013.01.014] [Citation(s) in RCA: 191] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 01/16/2013] [Indexed: 01/22/2023]
Abstract
Protein misfolding and aggregation are the hallmark of a number of diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and the prion diseases. In all cases, a naturally-occurring protein misfolds and forms aggregates that are thought to disrupt cell function through a wide range of mechanisms that are yet to be fully unraveled. Fourier transform infrared (FTIR) spectroscopy is a technique that is sensitive to the secondary structure of proteins and has been widely used to investigate the process of misfolding and aggregate formation. This review focuses on how FTIR spectroscopy and spectroscopic microscopy are being used to evaluate the structural changes in disease-related proteins both in vitro and directly within cells and tissues. Finally, ongoing technological advances will be presented that are enabling time-resolved FTIR imaging of protein aggregation directly within living cells, which can provide insight into the structural intermediates, time scale, and mechanisms of cell toxicity associated with aggregate formation. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.
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Affiliation(s)
- Lisa M Miller
- Photon Sciences Directorate, Brookhaven National Laboratory, Upton, NY 11973, USA.
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170
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Kazarian SG, Chan KLA. ATR-FTIR spectroscopic imaging: recent advances and applications to biological systems. Analyst 2013; 138:1940-51. [DOI: 10.1039/c3an36865c] [Citation(s) in RCA: 267] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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171
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Janssens K, Alfeld M, Van der Snickt G, De Nolf W, Vanmeert F, Radepont M, Monico L, Dik J, Cotte M, Falkenberg G, Miliani C, Brunetti BG. The use of synchrotron radiation for the characterization of artists' pigments and paintings. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2013; 6:399-425. [PMID: 23772661 DOI: 10.1146/annurev-anchem-062012-092702] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We review methods and recent studies in which macroscopic to (sub)microscopic X-ray beams were used for nondestructive analysis and characterization of pigments, paint microsamples, and/or entire paintings. We discuss the use of portable laboratory- and synchrotron-based instrumentation and describe several variants of X-ray fluorescence (XRF) analysis used for elemental analysis and imaging and combined with X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). Macroscopic and microscopic (μ-)XRF variants of this method are suitable for visualizing the elemental distribution of key elements in paint multilayers. Technical innovations such as multielement, large-area XRF detectors have enabled such developments. The use of methods limited to elemental analysis or imaging usually is not sufficient to elucidate the chemical transformations that take place during natural pigment alteration processes. However, synchrotron-based combinations of μ-XRF, μ-XAS, and μ-XRD are suitable for such studies.
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Affiliation(s)
- Koen Janssens
- Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
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172
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Reddy RK, Walsh MJ, Schulmerich MV, Carney PS, Bhargava R. High-definition infrared spectroscopic imaging. APPLIED SPECTROSCOPY 2013; 67:93-105. [PMID: 23317676 PMCID: PMC3893056 DOI: 10.1366/11-06568] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The quality of images from an infrared (IR) microscope has traditionally been limited by considerations of throughput and signal-to-noise ratio (SNR). An understanding of the achievable quality as a function of instrument parameters, from first principals is needed for improved instrument design. Here, we first present a model for light propagation through an IR spectroscopic imaging system based on scalar wave theory. The model analytically describes the propagation of light along the entire beam path from the source to the detector. The effect of various optical elements and the sample in the microscope is understood in terms of the accessible spatial frequencies by using a Fourier optics approach and simulations are conducted to gain insights into spectroscopic image formation. The optimal pixel size at the sample plane is calculated and shown much smaller than that in current mid-IR microscopy systems. A commercial imaging system is modified, and experimental data are presented to demonstrate the validity of the developed model. Building on this validated theoretical foundation, an optimal sampling configuration is set up. Acquired data were of high spatial quality but, as expected, of poorer SNR. Signal processing approaches were implemented to improve the spectral SNR. The resulting data demonstrated the ability to perform high-definition IR imaging in the laboratory by using minimally-modified commercial instruments.
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Affiliation(s)
- Rohith K. Reddy
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Urbana, IL
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL
| | - Michael J. Walsh
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL
| | - Matthew V. Schulmerich
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Urbana, IL
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL
| | - P. Scott Carney
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL
- Department of Electrical and Computer Engineering, University of Illinois at Urbana–Champaign, Urbana, IL
| | - Rohit Bhargava
- Department of Bioengineering, University of Illinois at Urbana–Champaign, Urbana, IL
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, Urbana, IL
- Department of Electrical and Computer Engineering, University of Illinois at Urbana–Champaign, Urbana, IL
- Department of Mechanical Science and Engineering, Micro and Nanotechnology Laboratory and University of Illinois Cancer Center, University of Illinois at Urbana–Champaign, Urbana, IL 61801 USA
- Author to whom correspondence should be sent:
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173
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Clède S, Lambert F, Sandt C, Kascakova S, Unger M, Harté E, Plamont MA, Saint-Fort R, Deniset-Besseau A, Gueroui Z, Hirschmugl C, Lecomte S, Dazzi A, Vessières A, Policar C. Detection of an estrogen derivative in two breast cancer cell lines using a single core multimodal probe for imaging (SCoMPI) imaged by a panel of luminescent and vibrational techniques. Analyst 2013; 138:5627-38. [DOI: 10.1039/c3an00807j] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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174
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Ling S, Qi Z, Knight DP, Shao Z, Chen X. FTIR imaging, a useful method for studying the compatibility of silk fibroin-based polymer blends. Polym Chem 2013. [DOI: 10.1039/c3py00508a] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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175
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Silien C, Liu N, Hendaoui N, Tofail SAM, Peremans A. A framework for far-field infrared absorption microscopy beyond the diffraction limit. OPTICS EXPRESS 2012; 20:29694-29704. [PMID: 23388797 DOI: 10.1364/oe.20.029694] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A framework is proposed for infrared (IR) absorption microscopy in the far-field with a spatial resolution below the diffraction limit. The sub-diffraction resolution is achieved by pumping a transient contrast in the population of a selected vibrational mode with IR pulses that exhibit alternating central minima and maxima, and by probing the corresponding absorbance at the same wavelength with adequately delayed Gaussian pulses. Simulations have been carried out on the basis of empirical parameters emulating patterned thin films of octadecyltrichlorosilane and a resolution of 250 nm was found when probing the CH₂ stretches at 3.5 μm with pump energies less than ten times the vibrational saturation threshold.
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Affiliation(s)
- Christophe Silien
- Department of Physics and Energy, and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
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176
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Chan KLA, Kazarian SG. Correcting the Effect of Refraction and Dispersion of Light in FT-IR Spectroscopic Imaging in Transmission through Thick Infrared Windows. Anal Chem 2012; 85:1029-36. [DOI: 10.1021/ac302846d] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- K. L. Andrew Chan
- Department of Chemical
Engineering, Imperial College London, SW7 2AZ, United Kingdom
| | - Sergei G. Kazarian
- Department of Chemical
Engineering, Imperial College London, SW7 2AZ, United Kingdom
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177
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Kole MR, Reddy RK, Schulmerich MV, Gelber MK, Bhargava R. Discrete frequency infrared microspectroscopy and imaging with a tunable quantum cascade laser. Anal Chem 2012; 84:10366-72. [PMID: 23113653 PMCID: PMC3514576 DOI: 10.1021/ac302513f] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Fourier-transform infrared (FT-IR) imaging is a well-established modality but requires the acquisition of a spectrum over a large bandwidth, even in cases where only a few spectral features may be of interest. Discrete frequency infrared (DF-IR) methods are now emerging in which a small number of measurements may provide all the analytical information needed. The DF-IR approach is enabled by the development of new sources integrating frequency selection, in particular of tunable, narrow-bandwidth sources with enough power at each wavelength to successfully make absorption measurements. Here, we describe a DF-IR imaging microscope that uses an external cavity quantum cascade laser (QCL) as a source. We present two configurations, one with an uncooled bolometer as a detector and another with a liquid nitrogen cooled mercury cadmium telluride (MCT) detector and compare their performance to a commercial FT-IR imaging instrument. We examine the consequences of the coherent properties of the beam with respect to imaging and compare these observations to simulations. Additionally, we demonstrate that the use of a tunable laser source represents a distinct advantage over broadband sources when using a small aperture (narrower than the wavelength of light) to perform high-quality point mapping. The two advances highlight the potential application areas for these emerging sources in IR microscopy and imaging.
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Affiliation(s)
- Matthew R. Kole
- Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Rohith K. Reddy
- Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Matthew V. Schulmerich
- Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Matthew K. Gelber
- Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
| | - Rohit Bhargava
- Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
- Department of Mechanical Science and Engineering, Electrical and Computer Engineering, Micro and Nanotechnology Laboratory and University of Illinois Cancer Center, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
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178
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Riding MJ, Trevisan J, Hirschmugl CJ, Jones KC, Semple KT, Martin FL. Mechanistic insights into nanotoxicity determined by synchrotron radiation-based Fourier-transform infrared imaging and multivariate analysis. ENVIRONMENT INTERNATIONAL 2012; 50:56-65. [PMID: 23085685 DOI: 10.1016/j.envint.2012.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 09/20/2012] [Accepted: 09/20/2012] [Indexed: 06/01/2023]
Abstract
Our ability to identify the mechanisms by which carbon-based nanomaterials (CBNs) exert toxicity in cells is constrained by the lack of standardized methodologies to assay endpoint effects. Herein we describe a method of mechanistically identifying the effects of various CBN types in both prokaryotic and eukaryotic cells using multi-beam synchrotron radiation-based Fourier-transform infrared imaging (SR-FTIRI) at diffraction-limited resolution. This technique overcomes many of the inherent difficulties of assaying nanotoxicity and demonstrates exceptional sensitivity in identifying the effects of CBNs in cells at environmentally-relevant concentrations. We identify key mechanisms of nanotoxicity as the alteration of Amide and lipid biomolecules, but propose more specific bioactivity of CBNs occurs as a result of specific interactions between CBN structural conformation and cellular characteristics.
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Affiliation(s)
- Matthew J Riding
- Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster, UK
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179
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Krafft C, Belay B, Bergner N, Romeike BFM, Reichart R, Kalff R, Popp J. Advances in optical biopsy--correlation of malignancy and cell density of primary brain tumors using Raman microspectroscopic imaging. Analyst 2012; 137:5533-7. [PMID: 23050263 DOI: 10.1039/c2an36083g] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Raman spectroscopy is a promising tool towards biopsy under vision as it provides label-free image contrast based on intrinsic vibrational spectroscopic fingerprints of the specimen. The current study applied the spectral unmixing algorithm vertex component analysis (VCA) to probe cell density and cell nuclei in Raman images of primary brain tumor tissue sections. Six Raman images were collected at 785 nm excitation that consisted of 61 by 61 spectra at a step size of 2 micrometers. After data acquisition the samples were stained with hematoxylin and eosin for comparison. VCA abundance plots coincided well with histopathological findings. Raman spectra of high grade tumor cells were found to contain more intense spectral contributions of nucleic acids than those of low grade tumor cells. Similarly, VCA endmember signatures of Raman images from high grade gliomas showed increased nucleic acid bands. Further abundance plots and endmember spectra were assigned to tissue containing proteins and lipids, and cholesterol microcrystals. Since no sample preparation is required, an important advantage of the Raman imaging methodology is that all tissue components can be observed - even those that may be lost in sample staining steps. The results demonstrate how morphology and chemical composition obtained by Raman imaging correlate with histopathology and provide complementary, diagnostically relevant information at the cellular level.
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Affiliation(s)
- Christoph Krafft
- Institute of Photonic Technology, Albert-Einstein-Str 9, 07745 Jena, Germany.
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180
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Abstract
Infrared (IR) spectroscopic imaging seemingly matured as a technology in the mid-2000s, with commercially successful instrumentation and reports in numerous applications. Recent developments, however, have transformed our understanding of the recorded data, provided capability for new instrumentation, and greatly enhanced the ability to extract more useful information in less time. These developments are summarized here in three broad areas--data recording, interpretation of recorded data, and information extraction--and their critical review is employed to project emerging trends. Overall, the convergence of selected components from hardware, theory, algorithms, and applications is one trend. Instead of similar, general-purpose instrumentation, another trend is likely to be diverse and application-targeted designs of instrumentation driven by emerging component technologies. The recent renaissance in both fundamental science and instrumentation will likely spur investigations at the confluence of conventional spectroscopic analyses and optical physics for improved data interpretation. While chemometrics has dominated data processing, a trend will likely lie in the development of signal processing algorithms to optimally extract spectral and spatial information prior to conventional chemometric analyses. Finally, the sum of these recent advances is likely to provide unprecedented capability in measurement and scientific insight, which will present new opportunities for the applied spectroscopist.
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Affiliation(s)
- Rohit Bhargava
- Department of Bioengineering, Beckman Institute for Advanced Science and Technology, University of Illinois Cancer Center, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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181
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Cui S, Pu H, Mattson EC, Lu G, Mao S, Weinert M, Hirschmugl CJ, Gajdardziska-Josifovska M, Chen J. Ag nanocrystal as a promoter for carbon nanotube-based room-temperature gas sensors. NANOSCALE 2012; 4:5887-5894. [PMID: 22899322 DOI: 10.1039/c2nr31556d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have investigated the room-temperature sensing enhancement of Ag nanoparticles (NPs) for multiwalled carbon nanotube (MWCNT)-based gas sensors using electrical measurements, in situ infrared (IR) microspectroscopy, and density functional theory (DFT) calculations. Multiple hybrid nanosensors with structures of MWCNTs/SnO(2)/Ag and MWCNTs/Ag have been synthesized using a process that combines a simple mini-arc plasma with electrostatic force directed assembly, and characterized by electron microscopy techniques. Ag NPs were found to enhance the sensing behavior through the "electronic sensitization" mechanism. In contrast to sensors based on bare MWCNTs and MWCNTs/SnO(2), sensors with Ag NPs show not only higher sensitivity and faster response to NO(2) but also significantly enhanced sensitivity to NH(3). Our DFT calculations indicate that the increased sensitivity to NO(2) is attributed to the formation of a NO(3) complex with oxygen on the Ag surface accompanying a charge rearrangement and a net electron transfer from the hybrid to NO(2). The significant response to NH(3) is predicted to arise because NH(3) is attracted to hollow sites on the oxidized Ag surface with the H atoms pointing towards Ag atoms and electron donation from H to the hybrid sensor.
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Affiliation(s)
- Shumao Cui
- Department of Mechanical Engineering, University of Wisconsin-Milwaukee, 3200 N Cramer Street, Milwaukee, WI 53211, USA
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182
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Chen K, Adato R, Altug H. Dual-band perfect absorber for multispectral plasmon-enhanced infrared spectroscopy. ACS NANO 2012; 6:7998-8006. [PMID: 22920565 DOI: 10.1021/nn3026468] [Citation(s) in RCA: 173] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Metamaterial-based perfect absorbers utilize intrinsic loss, with the aid of appropriate structural design, to achieve near unity absorption at a certain wavelength. For most of the reported absorbers, the absorption occurs only at a single wavelength where plasmon resonances are excited in the nanostructures. Here we introduce a dual-band perfect absorber based on a gold nanocross structure. Two bands of maximum absorption of 94% are experimentally accomplished by breaking the symmetry of the cross structure. Furthermore, we demonstrate the two bands can be readily tuned throughout the mid-infrared with their associated resonances giving rise to large near-field enhancements. These features are ideal for multiband surface-enhanced infrared spectroscopy applications. We experimentally demonstrate this application by simultaneously detecting two molecular vibrational modes of a 4 nm thick polymer film utilizing our proposed absorber. Furthermore, in response to variations in the interaction strength between the plasmonic and molecular dipoles, we observe an anticrossing behavior and modification in the spectral line shape of the molecular absorption peak, which are characteristic of the coupling between the two modes.
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Affiliation(s)
- Kai Chen
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215, United States
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183
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Isolating stem cells in the inter-follicular epidermis employing synchrotron radiation-based Fourier-transform infrared microspectroscopy and focal plane array imaging. Anal Bioanal Chem 2012; 404:1745-58. [PMID: 22945554 DOI: 10.1007/s00216-012-6314-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/27/2012] [Accepted: 07/30/2012] [Indexed: 01/03/2023]
Abstract
Normal function and physiology of the epidermis is maintained by the regenerative capacity of this tissue via adult stem cells (SCs). However, definitive identifying markers for SCs remain elusive. Infrared (IR) spectroscopy exploits the ability of cellular biomolecules to absorb in the mid-IR region (λ = 2.5-25 μm), detecting vibrational transitions of chemical bonds. In this study, we exploited the cell's inherent biochemical composition to discriminate SCs of the inter-follicular skin epidermis based on IR-derived markers. Paraffin-embedded samples of human scalp skin (n = 4) were obtained, and 10-μm thick sections were mounted for IR spectroscopy. Samples were interrogated in transmission mode using synchrotron radiation-based Fourier-transform IR (FTIR) microspectroscopy (15 × 15 μm) and also imaged employing globar-source FTIR focal plane array (FPA) imaging (5.4 × 5.4 μm). Dependent on the location of derived spectra, wavenumber-absorbance/intensity relationships were examined using unsupervised principal component analysis. This approach showed clear separation and spectral differences dependent on cell type. Spectral biomarkers concurrently associated with segregation of SCs, transit-amplifying cells and terminally-differentiated cells of epidermis were primarily PO(2)(-) vibrational modes (1,225 and 1,080 cm(-1)), related to DNA conformational alterations. FPA imaging coupled with hierarchical cluster analysis also indicated the presence of specific basal layer cells potentially originating from the follicular bulge, suggested by co-clustering of spectra. This study highlights PO (2) (-) vibrational modes as potential putative SC markers.
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184
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Pallua JD, Pezzei C, Zelger B, Schaefer G, Bittner LK, Huck-Pezzei VA, Schoenbichler SA, Hahn H, Kloss-Brandstaetter A, Kloss F, Bonn GK, Huck CW. Fourier transform infrared imaging analysis in discrimination studies of squamous cell carcinoma. Analyst 2012; 137:3965-74. [PMID: 22792538 DOI: 10.1039/c2an35483g] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Oral squamous cell carcinoma (OSCC) of the oral cavity and oropharynx represents more than 95% of all malignant neoplasms in the oral cavity. Histomorphological evaluation of this cancer type is invasive and remains a time consuming and subjective technique. Therefore, novel approaches for histological recognition are necessary to identify malignancy at an early stage. Fourier transform infrared (FTIR) imaging has become an essential tool for the detection and characterization of the molecular components of biological processes, such as those responsible for the dynamic properties of tumor progression. FTIR imaging is a modern analytical technique enabling molecular imaging of a complex biological sample and is based on the absorption of IR radiation by vibrational transitions in covalent bonds. One major advantage of this technique is the acquisition of local molecular expression profiles, while maintaining the topographic integrity of the tissue and avoiding time-consuming extraction, purification, and separation steps. With this imaging technique, it is possible to obtain unique images of the spatial distribution of proteins, lipids, carbohydrates, cholesterols, nucleic acids, phospholipids, and small molecules with high spatial resolution. Analysis and visualization of FTIR imaging datasets are challenging and the use of chemometric tools is crucial in order to take advantage of the full measurement. Therefore, methodologies for this task based on the novel developed algorithm for multivariate image analysis (MIA) are often necessary. In the present study, FTIR imaging and data analysis methods were combined to optimize the tissue measurement mode after deparaffinization and subsequent data evaluation (univariate analysis and MIAs). We demonstrate that it is possible to collect excellent IR spectra from formalin-fixed paraffin-embedded (FFPE) tissue microarrays (TMAs) of OSCC tissue sections employing an optimised analytical protocol. The correlation of FTIR imaging to the morphological tissue features obtained by histological staining of the sections demonstrated that many histomorphological tissue patterns can be visualized in the colour images. The different algorithms used for MIAs of FTIR imaging data dramatically increased the information content of the IR images from squamous cell tissue sections. These findings indicate that intra-operative and surgical specimens of squamous cell carcinoma tissue can be characterized by FTIR imaging.
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Affiliation(s)
- J D Pallua
- Institute of Analytical Chemistry and Radiochemistry, CCB-Center for Chemistry and Biomedicine, Leopold-Franzens University, Innrain 80-82-52a, 6020 Innsbruck, Austria
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185
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Mattson EC, Nasse MJ, Rak M, Gough KM, Hirschmugl CJ. Restoration and Spectral Recovery of Mid-Infrared Chemical Images. Anal Chem 2012; 84:6173-80. [DOI: 10.1021/ac301080h] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eric C. Mattson
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211,
United States
| | - Michael J. Nasse
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211,
United States
- Synchrotron
Radiation Center,
University of Wisconsin, Wisconsin 53589,
United States
| | - Margaret Rak
- Department
of Chemistry, University of Manitoba, Winnipeg,
Canada, R3T 2N2
| | - Kathleen M. Gough
- Department
of Chemistry, University of Manitoba, Winnipeg,
Canada, R3T 2N2
| | - Carol J. Hirschmugl
- Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211,
United States
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186
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Vaccari L, Birada G, Grenci G, Pacor S, Businaro L. Synchrotron radiation infrared microspectroscopy of single living cells in microfluidic devices: advantages, disadvantages and future perspectives. ACTA ACUST UNITED AC 2012. [DOI: 10.1088/1742-6596/359/1/012007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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187
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Walsh MJ, Kajdacsy-Balla A, Holton SE, Bhargava R. Attenuated total reflectance Fourier-transform infrared spectroscopic imaging for breast histopathology. VIBRATIONAL SPECTROSCOPY 2012; 60:23-28. [PMID: 22773893 PMCID: PMC3388548 DOI: 10.1016/j.vibspec.2012.01.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Histopathology forms the gold standard for the diagnosis of breast cancer. Fourier Transform Infrared (FT-IR) spectroscopic imaging has been proposed to be a potentially powerful adjunct to current histopathological techniques. Most studies using FT-IR imaging for breast tissue analysis have been in the transmission or transmission-reflection mode, in which the wavelength and optics limit the data to a relatively coarse spatial resolution (typically, coarser than 5 μm × 5 μm per pixel). This resolution is insufficient to examine many histologic structures. Attenuated Total Reflectance (ATR) FT-IR imaging incorporating a Germanium optic can allow for a four-fold increase in spatial resolution due to the material's high refractive index in the mid-IR. Here, we employ ATR FT-IR imaging towards examining cellular and tissue structures that constitute and important component of breast cancer diagnosis. In particular, we resolve and chemically characterize endothelial cells, myoepithelial cells and terminal ductal lobular units. Further extending the ability of IR imaging to examine sub-cellular structures, we report the extraction of intact chromosomes from a breast cancer cells and their spatially localized analysis as a novel approach to understand changes associated with the molecular structure of DNA in breast cancer.
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Affiliation(s)
- Michael J. Walsh
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL
| | | | - Sarah E. Holton
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Rohit Bhargava
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL
- University of Illinois Cancer Center, University of Illinois at Urbana-Champaign, Urbana, IL
- Electrical and Computer Engineering, Mechanical Science and Engineering and Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL
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188
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Hirschmugl CJ, Gough KM. Fourier transform infrared spectrochemical imaging: review of design and applications with a focal plane array and multiple beam synchrotron radiation source. APPLIED SPECTROSCOPY 2012; 66:475-91. [PMID: 22524953 DOI: 10.1366/12-06629] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The beamline design, microscope specifications, and initial results from the new mid-infrared beamline (IRENI) are reviewed. Synchrotron-based spectrochemical imaging, as recently implemented at the Synchrotron Radiation Center in Stoughton, Wisconsin, demonstrates the new capability to achieve diffraction limited chemical imaging across the entire mid-infrared region, simultaneously, with high signal-to-noise ratio. IRENI extracts a large swath of radiation (320 hor. × 25 vert. mrads(2)) to homogeneously illuminate a commercial infrared (IR) microscope equipped with an IR focal plane array (FPA) detector. Wide-field images are collected, in contrast to single-pixel imaging from the confocal geometry with raster scanning, commonly used at most synchrotron beamlines. IRENI rapidly generates high quality, high spatial resolution data. The relevant advantages (spatial oversampling, speed, sensitivity, and signal-to-noise ratio) are discussed in detail and demonstrated with examples from a variety of disciplines, including formalin-fixed and flash-frozen tissue samples, live cells, fixed cells, paint cross-sections, polymer fibers, and novel nanomaterials. The impact of Mie scattering corrections on this high quality data is shown, and first results with a grazing angle objective are presented, along with future enhancements and plans for implementation of similar, small-scale instruments.
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Affiliation(s)
- Carol J Hirschmugl
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
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189
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Chen L, Holman HYN, Hao Z, Bechtel HA, Martin MC, Wu C, Chu S. Synchrotron Infrared Measurements of Protein Phosphorylation in Living Single PC12 Cells during Neuronal Differentiation. Anal Chem 2012; 84:4118-25. [DOI: 10.1021/ac300308x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Liang Chen
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
| | - Hoi-Ying N. Holman
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
| | - Zhao Hao
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
| | - Hans A. Bechtel
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
| | - Michael C. Martin
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California
94720, United States
| | - Chengbiao Wu
- Department
of Neurosciences, University of California at San Diego School of Medicine, La Jolla, California 92093, United
States
| | - Steven Chu
- Departments of Physics
and Molecular
and Cell Biology, University of California at Berkeley, Berkeley, California 94720, United States
- California Institute for Quantitative
Biosciences (QB3), University of California at Berkeley, Berkeley, California 94720, United States
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190
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Caine S, Heraud P, Tobin MJ, McNaughton D, Bernard CC. The application of Fourier transform infrared microspectroscopy for the study of diseased central nervous system tissue. Neuroimage 2012; 59:3624-40. [DOI: 10.1016/j.neuroimage.2011.11.033] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 10/20/2011] [Accepted: 11/09/2011] [Indexed: 12/13/2022] Open
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191
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Trevisan J, Angelov PP, Carmichael PL, Scott AD, Martin FL. Extracting biological information with computational analysis of Fourier-transform infrared (FTIR) biospectroscopy datasets: current practices to future perspectives. Analyst 2012; 137:3202-15. [DOI: 10.1039/c2an16300d] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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192
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Abstract
This paper reviews work carried out in the Centre for Biospectroscopy, Monash University, at the Infrared Microspectroscopy Beamline on the Australian Synchrotron since the first synchrotron light. It discusses the attributes and advantages of the beamline for chemical spectroscopy and imaging of cellular and tissue samples and briefly summarizes new techniques that will come online in the near future.
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193
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Long X, Nasse MJ, Ma Y, Qi L. From synthetic to biogenic Mg-containing calcites: a comparative study using FTIR microspectroscopy. Phys Chem Chem Phys 2012; 14:2255-63. [DOI: 10.1039/c2cp22453d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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194
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Kwak JT, Reddy R, Sinha S, Bhargava R. Analysis of variance in spectroscopic imaging data from human tissues. Anal Chem 2011; 84:1063-9. [PMID: 22148458 DOI: 10.1021/ac2026496] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The analysis of cell types and disease using Fourier transform infrared (FT-IR) spectroscopic imaging is promising. The approach lacks an appreciation of the limits of performance for the technology, however, which limits both researcher efforts in improving the approach and acceptance by practitioners. One factor limiting performance is the variance in data arising from biological diversity, measurement noise or from other sources. Here we identify the sources of variation by first employing a high throughout sampling platform of tissue microarrays (TMAs) to record a sufficiently large and diverse set data. Next, a comprehensive set of analysis of variance (ANOVA) models is employed to analyze the data. Estimating the portions of explained variation, we quantify the primary sources of variation, find the most discriminating spectral metrics, and recognize the aspects of the technology to improve. The study provides a framework for the development of protocols for clinical translation and provides guidelines to design statistically valid studies in the spectroscopic analysis of tissue.
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Affiliation(s)
- Jin Tae Kwak
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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195
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Mattson EC, Pu H, Cui S, Schofield MA, Rhim S, Lu G, Nasse MJ, Ruoff RS, Weinert M, Gajdardziska-Josifovska M, Chen J, Hirschmugl CJ. Evidence of nanocrystalline semiconducting graphene monoxide during thermal reduction of graphene oxide in vacuum. ACS NANO 2011; 5:9710-9717. [PMID: 22098501 DOI: 10.1021/nn203160n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
As silicon-based electronics are reaching the nanosize limits of the semiconductor roadmap, carbon-based nanoelectronics has become a rapidly growing field, with great interest in tuning the properties of carbon-based materials. Chemical functionalization is a proposed route, but syntheses of graphene oxide (G-O) produce disordered, nonstoichiometric materials with poor electronic properties. We report synthesis of an ordered, stoichiometric, solid-state carbon oxide that has never been observed in nature and coexists with graphene. Formation of this material, graphene monoxide (GMO), is achieved by annealing multilayered G-O. Our results indicate that the resulting thermally reduced G-O (TRG-O) consists of a two-dimensional nanocrystalline phase segregation: unoxidized graphitic regions are separated from highly oxidized regions of GMO. GMO has a quasi-hexagonal unit cell, an unusually high 1:1 O:C ratio, and a calculated direct band gap of ∼0.9 eV.
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Affiliation(s)
- Eric C Mattson
- Department of Physics and Laboratory for Surface Studies, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
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196
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Kastyak-Ibrahim MZ, Nasse MJ, Rak M, Hirschmugl C, Del Bigio MR, Albensi BC, Gough KM. Biochemical label-free tissue imaging with subcellular-resolution synchrotron FTIR with focal plane array detector. Neuroimage 2011; 60:376-83. [PMID: 22197789 DOI: 10.1016/j.neuroimage.2011.11.069] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 11/18/2011] [Accepted: 11/23/2011] [Indexed: 12/13/2022] Open
Abstract
The critical questions into the cause of neural degeneration, in Alzheimer disease and other neurodegenerative disorders, are closely related to the question of why certain neurons survive. Answers require detailed understanding of biochemical changes in single cells. Fourier transform infrared microspectroscopy is an excellent tool for biomolecular imaging in situ, but resolution is limited. The mid-infrared beamline IRENI (InfraRed ENvironmental Imaging) at the Synchrotron Radiation Center, University of Wisconsin-Madison, enables label-free subcellular imaging and biochemical analysis of neurons with an increase of two orders of magnitude in pixel spacing over current systems. With IRENI's capabilities, it is now possible to study changes in individual neurons in situ, and to characterize their surroundings, using only the biochemical signatures of naturally-occurring components in unstained, unfixed tissue. We present examples of analyses of brain from two transgenic mouse models of Alzheimer disease (TgCRND8 and 3xTg) that exhibit different features of pathogenesis. Data processing on spectral features for nuclei reveals individual hippocampal neurons, and neurons located in the proximity of amyloid plaque in TgCRND8 mouse. Elevated lipids are detected surrounding and, for the first time, within the dense core of amyloid plaques, offering support for inflammatory and aggregation roles. Analysis of saturated and unsaturated fatty acid ester content in retina allows characterization of neuronal layers. IRENI images also reveal spatially-resolved data with unprecedented clarity and distinct spectral variation, from sub-regions including photoreceptors, neuronal cell bodies and synapses in sections of mouse retina. Biochemical composition of retinal layers can be used to study changes related to disease processes and dietary modification.
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Affiliation(s)
- M Z Kastyak-Ibrahim
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
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197
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Bellisola G, Sorio C. Infrared spectroscopy and microscopy in cancer research and diagnosis. Am J Cancer Res 2011; 2:1-21. [PMID: 22206042 PMCID: PMC3236568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 09/10/2011] [Indexed: 05/31/2023] Open
Abstract
Since the middle of 20(th) century infrared (IR) spectroscopy coupled to microscopy (IR microspectroscopy) has been recognized as a non destructive, label free, highly sensitive and specific analytical method with many potential useful applications in different fields of biomedical research and in particular cancer research and diagnosis. Although many technological improvements have been made to facilitate biomedical applications of this powerful analytical technique, it has not yet properly come into the scientific background of many potential end users. Therefore, to achieve those fundamental objectives an interdisciplinary approach is needed with basic scientists, spectroscopists, biologists and clinicians who must effectively communicate and understand each other's requirements and challenges. In this review we aim at illustrating some principles of Fourier transform (FT) Infrared (IR) vibrational spectroscopy and microscopy (microFT-IR) as a useful method to interrogate molecules in specimen by mid-IR radiation. Penetrating into basics of molecular vibrations might help us to understand whether, when and how complementary information obtained by microFT-IR could become useful in our research and/or diagnostic activities. MicroFT-IR techniques allowing to acquire information about the molecular composition and structure of a sample within a micrometric scale in a matter of seconds will be illustrated as well as some limitations will be discussed. How biochemical, structural, and dynamical information about the systems can be obtained by bench top microFT-IR instrumentation will be also presented together with some methods to treat and interpret IR spectral data and applicative examples. The mid-IR absorbance spectrum is one of the most information-rich and concise way to represent the whole "… omics" of a cell and, as such, fits all the characteristics for the development of a clinically useful biomarker.
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Affiliation(s)
- Giuseppe Bellisola
- Department of Pathology and Diagnostics, Unit of Immunology, Azienda Ospedaliera Universitaria Integrata VeronaVerona, Italy
| | - Claudio Sorio
- Department of Pathology and Diagnostics, General Pathology Section, University of VeronaVerona, Italy
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198
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Marcott C, Lo M, Kjoller K, Prater C, Noda I. Spatial differentiation of sub-micrometer domains in a poly(hydroxyalkanoate) copolymer using instrumentation that combines atomic force microscopy (AFM) and infrared (IR) spectroscopy. APPLIED SPECTROSCOPY 2011; 65:1145-1150. [PMID: 21986074 DOI: 10.1366/11-06341] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Atomic force microscopy (AFM) and infrared (IR) spectroscopy have been combined in a single instrument (AFM-IR) capable of producing sub-micrometer spatial resolution IR spectra and absorption images. This new capability enables the spectroscopic characterization of microdomain-forming polymers at levels not previously possible. Films of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) were solution cast on ZnSe prisms, followed by melting and annealing to generate crystalline microdomains of different sizes. A tunable IR laser generating pulses of the order of 10 ns was used for excitation of the sample films. Short duration thermomechanical waves, due to infrared absorption and resulting thermal expansion, were studied by monitoring the resulting excitation of the contact resonance modes of the AFM cantilever. Dramatic differences in the room-temperature IR spectra are observed in the 1200-1300 cm(-1) range as a function of position on a spatial scale of less than one micrometer. This spectral region is particularly sensitive to the polymer backbone conformation. Such dramatic spectral differences have also been observed previously in bulk IR measurements, but only by comparing room-temperature spectra with ones collected at higher temperatures. Less dramatic, but significant, AFM-IR spectral differences are observed in the carbonyl stretching region around 1720 cm(-1) as a function of location on the sample. Two overlapping, but relatively sharp, carbonyl bands are observed near 1720 cm(-1) in more crystalline regions of the polymer, while a broader carbonyl stretching band appears centered at 1740 cm(-1) in the more amorphous regions. Using this spectral region, it is possible to monitor the development of polymer crystalline structures at varying distances from a nucleation site, where the site was generated by bringing a heated AFM tip close to a specific location to locally anneal the sample.
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Affiliation(s)
- Curtis Marcott
- Light Light Solutions, LLC, P. O. Box 81486, Athens, Georgia 30608-1486, USA.
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199
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Quaroni L, Zlateva T, Normand E. Detection of Weak Absorption Changes from Molecular Events in Time-Resolved FT-IR Spectromicroscopy Measurements of Single Functional Cells. Anal Chem 2011; 83:7371-80. [DOI: 10.1021/ac201318z] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Luca Quaroni
- Swiss Light Source, Paul Scherrer Institut, 5232, Villigen-PSI, Switzerland
| | - Theodora Zlateva
- Department of Biochemistry and Cancer Research Center, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Elise Normand
- Canadian Light Source Inc., University of Saskatchewan, Saskatoon, SK, S7N 0X4, Canada
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200
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Chemistry Methods. Nat Methods 2011. [DOI: 10.1038/nmeth0811-646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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