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Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level

Infrared (IR) spectroscopy has been used for decades to study collagen in mammalian tissues. While many changes in the spectral profiles appear under polarized IR light, the absorption bands are naturally broad because of tissue heterogeneity. A better understanding of the spectra of ordered collage...

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Autores principales: Bakir, Gorkem, Girouard, Benoit E., Wiens, Richard, Mastel, Stefan, Dillon, Eoghan, Kansiz, Mustafa, Gough, Kathleen M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7571167/
https://www.ncbi.nlm.nih.gov/pubmed/32961663
http://dx.doi.org/10.3390/molecules25184295
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author Bakir, Gorkem
Girouard, Benoit E.
Wiens, Richard
Mastel, Stefan
Dillon, Eoghan
Kansiz, Mustafa
Gough, Kathleen M.
author_facet Bakir, Gorkem
Girouard, Benoit E.
Wiens, Richard
Mastel, Stefan
Dillon, Eoghan
Kansiz, Mustafa
Gough, Kathleen M.
author_sort Bakir, Gorkem
collection PubMed
description Infrared (IR) spectroscopy has been used for decades to study collagen in mammalian tissues. While many changes in the spectral profiles appear under polarized IR light, the absorption bands are naturally broad because of tissue heterogeneity. A better understanding of the spectra of ordered collagen will aid in the evaluation of disorder in damaged collagen and in scar tissue. To that end, collagen spectra have been acquired with polarized far-field (FF) Fourier Transform Infrared (FTIR) imaging with a Focal Plane Array detector, with the relatively new method of FF optical photothermal IR (O-PTIR), and with nano-FTIR spectroscopy based on scattering-type scanning near-field optical microscopy (s-SNOM). The FF methods were applied to sections of intact tendon with fibers aligned parallel and perpendicular to the polarized light. The O-PTIR and nano-FTIR methods were applied to individual fibrils of 100–500 nm diameter, yielding the first confirmatory and complementary results on a biopolymer. We observed that the Amide I and II bands from the fibrils were narrower than those from the intact tendon, and that both relative intensities and band shapes were altered. These spectra represent reliable profiles for normal collagen type I fibrils of this dimension, under polarized IR light, and can serve as a benchmark for the study of collagenous tissues.
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spelling pubmed-75711672020-10-28 Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level Bakir, Gorkem Girouard, Benoit E. Wiens, Richard Mastel, Stefan Dillon, Eoghan Kansiz, Mustafa Gough, Kathleen M. Molecules Article Infrared (IR) spectroscopy has been used for decades to study collagen in mammalian tissues. While many changes in the spectral profiles appear under polarized IR light, the absorption bands are naturally broad because of tissue heterogeneity. A better understanding of the spectra of ordered collagen will aid in the evaluation of disorder in damaged collagen and in scar tissue. To that end, collagen spectra have been acquired with polarized far-field (FF) Fourier Transform Infrared (FTIR) imaging with a Focal Plane Array detector, with the relatively new method of FF optical photothermal IR (O-PTIR), and with nano-FTIR spectroscopy based on scattering-type scanning near-field optical microscopy (s-SNOM). The FF methods were applied to sections of intact tendon with fibers aligned parallel and perpendicular to the polarized light. The O-PTIR and nano-FTIR methods were applied to individual fibrils of 100–500 nm diameter, yielding the first confirmatory and complementary results on a biopolymer. We observed that the Amide I and II bands from the fibrils were narrower than those from the intact tendon, and that both relative intensities and band shapes were altered. These spectra represent reliable profiles for normal collagen type I fibrils of this dimension, under polarized IR light, and can serve as a benchmark for the study of collagenous tissues. MDPI 2020-09-19 /pmc/articles/PMC7571167/ /pubmed/32961663 http://dx.doi.org/10.3390/molecules25184295 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Bakir, Gorkem
Girouard, Benoit E.
Wiens, Richard
Mastel, Stefan
Dillon, Eoghan
Kansiz, Mustafa
Gough, Kathleen M.
Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level
title Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level
title_full Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level
title_fullStr Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level
title_full_unstemmed Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level
title_short Orientation Matters: Polarization Dependent IR Spectroscopy of Collagen from Intact Tendon Down to the Single Fibril Level
title_sort orientation matters: polarization dependent ir spectroscopy of collagen from intact tendon down to the single fibril level
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7571167/
https://www.ncbi.nlm.nih.gov/pubmed/32961663
http://dx.doi.org/10.3390/molecules25184295
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