title: Inclusion of cut and as-grown single-walled carbon nanotubes in the helical superstructure of schizophyllan and curdlan (beta-1,3-glucans).
abstract: We have found that single-chain schizophyllan and curdlan (s-SPG and s-curdlan, respectively) can dissolve as-grown and cut single-walled carbon nanotubes (ag-SWNTs and c-SWNTs, respectively) in aqueous solution. The vis-NIR spectra of the composites suggest that c-SWNTs are dissolved as a bundle, whereas ag-SWNTs exist as one or only a few pieces in the tubular hollow constructed by the helical structure inherent to these beta-1,3-glucans. EDX and CLSM measurements and TEM observation established that the distribution map of these polysaccharides overlaps well with the image of SWNTs, indicating that these two components form a composite. Very interestingly, when c-SWNTs were dissolved with the aid of s-SPG or s-curdlan in water, a clear periodical structure with inclined stripes, as detected by AFM, appeared on the fibrous composite surface. Because this periodical structure has never been recognized for the composites with other water-soluble polymers, one can regard that s-SPG or s-curdlan wraps c-SWNTs constructing a helically twined structure. High-resolution TEM observation of an ag-SWNTs/s-SPG composite gave a clearer image in that two s-SPG chains twine one ag-SWNT and the helical motif is right-handed. When this sample was subjected to the AFM measurement, the composite showed the 2-3 nm height. This height implies that one piece of ag-SWNT is included in the s-SPGs helical structure. As a summary, it has been established that beta-1,3-glucans such as s-SPG and s-curdlan not only dissolve SWNTs but also create a novel superstructure on the surface.
authors.affiliation: Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Munenori
authors.initials: M
authors.lastname: Numata
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Asai
authors.forename: Kenji
authors.initials: K
authors.lastname: Kaneko
authors.forename: Ah-Hyun
authors.initials: AH
authors.lastname: Bae
authors.forename: Teruaki
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakurai
authors.forename: Seiji
authors.initials: S
authors.lastname: Shinkai
mesh_terms: D002240:Carbohydrate Sequence; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D008969:Molecular Sequence Data; D037742:Nanotubes, Carbon / Q000737:chemistry*; D012566:Sizofiran / Q000737:chemistry*; D012996:Solutions; D019265:Spectroscopy, Near-Infrared; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry; D047071:beta-Glucans / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D012996:Solutions; D047071:beta-Glucans; D014867:Water; C038459:curdlan; D012566:Sizofiran