Revealing organization of cellulose in wood cell walls by Raman imaging

Abstract

Anisotropy of cellulose organization in mature black spruce wood cell wall was investigated by Raman imaging using a 1 [mu]m lateral-resolution capable confocal Raman microscope. In these studies, wood cross sections (CS) and radial longitudinal sections (LS) that were partially delignified by acid chlorite treatment were used. In the case of CS where latewood cells were examined, Raman images of S2 and S1 regions, produced using cellulose contribution at 1098 and 2773-3045 cm-1, showed significant differences. While the spectra associated with the S2 images indicated the microfibrillar orientation there to be longitudinal, in contrast, the spectra corresponding to the predominantly S1 images indicated that the net alignment of cellulose microfibrils in this region was transverse such that their long fibril axis made a small angle (~30°) to the S1 wall surface. Or in other words, cellulose in S1 was oriented approximately 60° to the expanding direction of the growing cells. In the CC regions, although as expected the intensities of the spectral contributions were quite low, they were due to cellulose. Additionally, results of the radial LS studies provided evidence that corroborated findings from the CS.

Citation

Agarwal, Umesh P.; Ralph, Sally A. 2007. Revealing organization of cellulose in wood cell walls by Raman imaging. Proceedings of the 14th International Symposium on Wood Fibre and Pulping Chemistry, held in Durban, South Africa, Technical Association of the Pulp and Paper Industry, TAPPSA, 6/25-6/28/2007. [S.l. : s.n.], 2007: [8] pages