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Cellulose microfibril orientation of Picea abies and its variability at the micron-level determined by Raman imaging.

Gierlinger N, Luss S, König C, Konnerth J, Eder M, Fratzl P - J. Exp. Bot. (2009)

Bottom Line: The functional characteristics of plant cell walls depend on the composition of the cell wall polymers, as well as on their highly ordered architecture at scales from a few nanometres to several microns.Raman spectra of wood acquired with linear polarized laser light include information about polymer composition as well as the alignment of cellulose microfibrils with respect to the fibre axis (microfibril angle).With the prerequisite of geometric sample and laser alignment, exact MFA prediction can complete the picture of the chemical cell wall design gained by the Raman imaging approach at the micron level in all plant tissues.

View Article: PubMed Central - PubMed

Affiliation: Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Strasse 69, Linz, Austria.

ABSTRACT
The functional characteristics of plant cell walls depend on the composition of the cell wall polymers, as well as on their highly ordered architecture at scales from a few nanometres to several microns. Raman spectra of wood acquired with linear polarized laser light include information about polymer composition as well as the alignment of cellulose microfibrils with respect to the fibre axis (microfibril angle). By changing the laser polarization direction in 3 degrees steps, the dependency between cellulose and laser orientation direction was investigated. Orientation-dependent changes of band height ratios and spectra were described by quadratic linear regression and partial least square regressions, respectively. Using the models and regressions with high coefficients of determination (R(2) > 0.99) microfibril orientation was predicted in the S1 and S2 layers distinguished by the Raman imaging approach in cross-sections of spruce normal, opposite, and compression wood. The determined microfibril angle (MFA) in the different S2 layers ranged from 0 degrees to 49.9 degrees and was in coincidence with X-ray diffraction determination. With the prerequisite of geometric sample and laser alignment, exact MFA prediction can complete the picture of the chemical cell wall design gained by the Raman imaging approach at the micron level in all plant tissues.

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Related in: MedlinePlus

(A, B) Loadings of the PLS-vectors (A), when regressing the baseline corrected normalized (1122 cm−1) spectra against the changing laser polarization angle [cos(α)2]. Relationship between true and predicted values in the cross validation using the wavenumber regions with high loading from 1208 to 887 cm−1 and 634 to 293 cm−1 (boxes in A) and three factors (black dircles) and one factor (white squares), respectively (B).
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fig4: (A, B) Loadings of the PLS-vectors (A), when regressing the baseline corrected normalized (1122 cm−1) spectra against the changing laser polarization angle [cos(α)2]. Relationship between true and predicted values in the cross validation using the wavenumber regions with high loading from 1208 to 887 cm−1 and 634 to 293 cm−1 (boxes in A) and three factors (black dircles) and one factor (white squares), respectively (B).

Mentions: Several partial least square (PLS) regression models were established with spectra normalized on the 1377 cm−1 or 1122 cm−1 band. The 1377 cm−1 band was chosen, because this band was least affected by orientation changes (Fig. 2), but resulted in less good models and prediction compared to normalization on the 1122 cm−1 band (data not shown). The 1122 cm−1 band was seen to increase moderately (Fig. 2), but was applicable as an intensive band, which can clearly be distinguished in all plant cell wall spectra, from which we want to determine the cellulose orientation in the next step. The lignin region was omitted and the spectral range selected according to the loadings of the first factors (Fig. 4A). The best model statistics were achieved with the spectra normalized on the 1122 cm−1 band and restricting the wavenumber region to 1208–887 cm−1 and 634–293 cm−1 (Fig. 4B; Table 2).


Cellulose microfibril orientation of Picea abies and its variability at the micron-level determined by Raman imaging.

Gierlinger N, Luss S, König C, Konnerth J, Eder M, Fratzl P - J. Exp. Bot. (2009)

(A, B) Loadings of the PLS-vectors (A), when regressing the baseline corrected normalized (1122 cm−1) spectra against the changing laser polarization angle [cos(α)2]. Relationship between true and predicted values in the cross validation using the wavenumber regions with high loading from 1208 to 887 cm−1 and 634 to 293 cm−1 (boxes in A) and three factors (black dircles) and one factor (white squares), respectively (B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2803219&req=5

fig4: (A, B) Loadings of the PLS-vectors (A), when regressing the baseline corrected normalized (1122 cm−1) spectra against the changing laser polarization angle [cos(α)2]. Relationship between true and predicted values in the cross validation using the wavenumber regions with high loading from 1208 to 887 cm−1 and 634 to 293 cm−1 (boxes in A) and three factors (black dircles) and one factor (white squares), respectively (B).
Mentions: Several partial least square (PLS) regression models were established with spectra normalized on the 1377 cm−1 or 1122 cm−1 band. The 1377 cm−1 band was chosen, because this band was least affected by orientation changes (Fig. 2), but resulted in less good models and prediction compared to normalization on the 1122 cm−1 band (data not shown). The 1122 cm−1 band was seen to increase moderately (Fig. 2), but was applicable as an intensive band, which can clearly be distinguished in all plant cell wall spectra, from which we want to determine the cellulose orientation in the next step. The lignin region was omitted and the spectral range selected according to the loadings of the first factors (Fig. 4A). The best model statistics were achieved with the spectra normalized on the 1122 cm−1 band and restricting the wavenumber region to 1208–887 cm−1 and 634–293 cm−1 (Fig. 4B; Table 2).

Bottom Line: The functional characteristics of plant cell walls depend on the composition of the cell wall polymers, as well as on their highly ordered architecture at scales from a few nanometres to several microns.Raman spectra of wood acquired with linear polarized laser light include information about polymer composition as well as the alignment of cellulose microfibrils with respect to the fibre axis (microfibril angle).With the prerequisite of geometric sample and laser alignment, exact MFA prediction can complete the picture of the chemical cell wall design gained by the Raman imaging approach at the micron level in all plant tissues.

View Article: PubMed Central - PubMed

Affiliation: Johannes Kepler University Linz, Institute of Polymer Science, Altenberger Strasse 69, Linz, Austria.

ABSTRACT
The functional characteristics of plant cell walls depend on the composition of the cell wall polymers, as well as on their highly ordered architecture at scales from a few nanometres to several microns. Raman spectra of wood acquired with linear polarized laser light include information about polymer composition as well as the alignment of cellulose microfibrils with respect to the fibre axis (microfibril angle). By changing the laser polarization direction in 3 degrees steps, the dependency between cellulose and laser orientation direction was investigated. Orientation-dependent changes of band height ratios and spectra were described by quadratic linear regression and partial least square regressions, respectively. Using the models and regressions with high coefficients of determination (R(2) > 0.99) microfibril orientation was predicted in the S1 and S2 layers distinguished by the Raman imaging approach in cross-sections of spruce normal, opposite, and compression wood. The determined microfibril angle (MFA) in the different S2 layers ranged from 0 degrees to 49.9 degrees and was in coincidence with X-ray diffraction determination. With the prerequisite of geometric sample and laser alignment, exact MFA prediction can complete the picture of the chemical cell wall design gained by the Raman imaging approach at the micron level in all plant tissues.

Show MeSH
Related in: MedlinePlus