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

Alexander J. Makowski; Isaac J. Pence; Sasidhar Uppuganti; Ahbid Zein-Sabatto; Meredith C. Huszagh; Anita Mahadevan-Jansen; Jeffry S. Nyman

doi:10.1117/1.JBO.19.11.117008

17 November 2014 Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models

Alexander J. Makowski, Isaac J. Pence, Sasidhar Uppuganti, Ahbid Zein-Sabatto, Meredith C. Huszagh, Anita Mahadevan-Jansen, Jeffry S. Nyman

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Journal of Biomedical Optics, Vol. 19, Issue 11, 117008 (November 2014). https://doi.org/10.1117/1.JBO.19.11.117008

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 mice—activating 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.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 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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Alexander J. Makowski, Isaac J. Pence, Sasidhar Uppuganti, Ahbid Zein-Sabatto, Meredith C. Huszagh, Anita Mahadevan-Jansen, and Jeffry S. Nyman "Polarization in Raman spectroscopy helps explain bone brittleness in genetic mouse models," Journal of Biomedical Optics 19(11), 117008 (17 November 2014). https://doi.org/10.1117/1.JBO.19.11.117008

Published: 17 November 2014

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