Microscopic structural study of collagen aging in isolated fibrils using polarized second harmonic generation

Aït-Belkacem, Dora

doi:10.1117/1.jbo.17.8.080506

Cited by 43 publications

(41 citation statements)

References 17 publications

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“…58 RS will not have the resolution of atomic force microscopy to map collagen d spacing, 59 nor the SNR of two photon fluorescence to examine collagen fiber orientation. 60 Nonetheless, the inherent interplay between chemical composition and tissue organization in RS polarization may prove useful in explaining changes in the fracture resistance of complex human microstructures. Ascenzi showed such complexity as mechanical properties of osteons for different loading modes (i.e., compression versus tension) were related to the primary collagen orientation relative to the directionality of the haversian canals.…”

Section: Discussionmentioning

confidence: 99%

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

et al. 2014

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Abstract. Raman spectroscopy (RS) has been extensively used to characterize bone composition. However, the link between bone biomechanics and RS measures is not well established. Here, we leveraged the sensitivity of RS polarization to organization, thereby assessing whether RS can explain differences in bone toughness in genetic mouse models for which traditional RS peak ratios are not informative. In the selected mutant miceactivating transcription factor 4 (ATF4) or matrix metalloproteinase 9 (MMP9) knock-outs-toughness is reduced but differences in bone strength do not exist between knock-out and corresponding wild-type controls. To incorporate differences in the RS of bone occurring at peak shoulders, a multivariate approach was used. Full spectrum principal components analysis of two paired, orthogonal bone orientations (relative to laser polarization) improved genotype classification and correlation to bone toughness when compared to traditional peak ratios. When applied to femurs from wild-type mice at 8 and 20 weeks of age, the principal components of orthogonal bone orientations improved age classification but not the explanation of the maturation-related increase in strength. Overall, increasing polarization information by collecting spectra from two bone orientations improves the ability of multivariate RS to explain variance in bone toughness, likely due to polarization sensitivity to organizational changes in both mineral and collagen.

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Section: Discussionmentioning

confidence: 99%

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

et al. 2014

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“…Methods like Raman microspectroscopy could produce complementary vibrational information and other biophotonic approaches like polarized second harmonic generation could help to image the cell/collagen contact zones and inform on morphological parameters, such as the molecular order, the degree of orientational freedom, the molecular constraint, and rigidity of the collagen fibers. 38 Indeed, these should be supported by conventional biochemical analysis.…”

Section: Discussionmentioning

confidence: 99%

Probing single-tumor cell interactions with different-age type I collagen networks by synchrotron-based Fourier transform infrared microspectroscopy

et al. 2014

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Abstract. We report here on a first study using synchrotron radiation-based Fourier transform infrared microspectroscopy and imaging to investigate HT1080 human fibrosarcoma cells grown onto different-aged type I collagen networks. Spectral images were analyzed with k-means and fuzzy C-means (FCM) clustering algorithms. K -means delineated tumor cells from their surrounding collagen networks and the latter as a function of age mainly due to specific changes in the sugar absorption region. The FCM analysis gave a better nuance of the spectral images. A progression of the biochemical information was observed upon going from the cellular compartments to the pericellular contact regions and to the intact collagens of the different age groups. Two spectral markers based on sugar and protein bands via the intensity ratio (I 1032 ∕I 1655 ) and band area ratio (A sugar ∕A amide II ), showed an increase in advanced glycation endproducts (AGEs) with age. A clear-separation of the three age groups was obtained for spectra originating from the peripheral contact areas mainly due to changes in protein band intensities. The above-described markers decreased to constant levels for the three conditions indicating a masking of the biochemical information. These results hold promises to better understand the impact of age on tumor progression processes while highlighting new markers of the tumor cell invasion front. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…High-order nonlinear light-matter interactions in two-photon excitation processes are able to bring a level of detail on molecular orientational distributions, which is not accessible in linear optics [1]. Recent developments in two-photon excited fluorescence (TPEF) in labeled cell membranes [3,4] and second harmonic generation (SHG) in collagen from extracted structures [5,6] and tissues [7][8][9] have shown in particular the possibility to decipher informative molecular order properties based on the analysis of the signal dependence to a tunable incident polarization. These experiments are, however, often performed in low signal regimes approaching photon noise, which leads to uncertainty in the retrieved parameter values.…”

Section: Introduction and Background A Introductionmentioning

confidence: 99%

Precision of polarization-resolved second harmonic generation microscopy limited by photon noise for samples with cylindrical symmetry

et al. 2015

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The estimation of parameters in polarization-resolved two-photon microscopy response perturbed by photon noise is analyzed in the context of second harmonic generation for the distribution of molecules presenting cylindrical symmetry. The estimation task is investigated using the Cramer-Rao lower bound for Poisson photon noise. It is shown that a noniterative technique can lead to estimation results that have good efficiencies for most of the physical possible values of the sample parameters for sufficiently high photon levels. The trade-off, between the number of incident polarization states and the total number of measured photons, that can be obtained with the Cramer-Rao lower bound is also discussed.

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Microscopic structural study of collagen aging in isolated fibrils using polarized second harmonic generation

Cited by 43 publications

References 17 publications

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

Probing single-tumor cell interactions with different-age type I collagen networks by synchrotron-based Fourier transform infrared microspectroscopy

Precision of polarization-resolved second harmonic generation microscopy limited by photon noise for samples with cylindrical symmetry

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