title: Macromolecular structure of cellulose studied by second-harmonic generation imaging microscopy.
abstract: The macromolecular structure of purified cellulose samples is studied by second-harmonic generation (SHG) imaging microscopy. We show that the SHG contrast in both Valonia and Acetobacter cellulose strongly resembles that of collagen from animal tissues, both in terms of morphology and polarization anisotropy. Polarization analysis shows that microfibrils in each lamella are highly aligned and ordered and change directions by 90 degrees in adjacent lamellae. The angular dependence of the SHG intensity fits well to a cos2 theta distribution, which is characteristic of the electric dipole interaction. Enzymatic degradation of Valonia fibers by cellulase is followed in real time by SHG imaging and results in exponential decay kinetics, showing that SHG imaging microscopy is ideal for monitoring dynamics in biological systems.
authors.affiliation: Section of Molecular Genetics and Microbiology, University of Texas, Austin, Austin, Texas 78712, USA.
authors.forename: R Malcom
authors.initials: RM
authors.lastname: Brown
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Millard
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Campagnola
mesh_terms: D000091:Acetobacter / Q000737:chemistry; D016880:Anisotropy; D002482:Cellulose / Q000737:chemistry*; D000460:Chlorophyta / Q000737:chemistry; D003952:Diagnostic Imaging; D046911:Macromolecular Substances; D018613:Microscopy, Confocal; D008859:Microscopy, Polarization; D015394:Molecular Structure; D055095:Optics and Photonics
chemical_list: D046911:Macromolecular Substances; D002482:Cellulose