Formation and structure of the complexes of sub-elementary fibrils of bacterial cellulose with fluorescent brightener molecules
Tóm tắt
The formation and structure of the complexes of sub-elementary fibrils (SEFs) of bacterial cellulose with fluorescent brightener (FB) molecules have been investigated using WAXD, SEM, and computer calculations of WAXD profiles. It is confirmed for the first time that the SEF-FB complexes are formed in 10 min by washing the cultivation product, which is prepared by the culture of Acetobacter xylinum in the presence of FB, with the pH 7 citrate–phosphate buffer solution and their thin sheet-like structure is grown almost two-dimensionally in 24 h in the medium. The same SEF-FB complexes are also produced by washing the product with NaCl aqueous solutions having concentrations higher than 0.1 wt%, while the original SEF structure is unchanged at lower concentrations. This indicates that the concentration of salt ions in washing media is a main factor to dominate the formation of the SEF-FB complexes from the cultivation product. The calculations of WAXD profiles reveal that the chain-slid, parallel-set, and sheet-slid/contracted models well reproduce the WAXD profile observed for the SEF-FB complexes. In these models, the following modifications are conducted in the a,b-modified unit cell of cellulose I
β
; the slide of the center chain along the b″ axis, the rotation of each chain around its own molecular axis, and the slide and contraction of the individual sheets composed of the center or origin chains. A single FB molecule is successfully packed into an energetically-allowable space in between the (010) planes in the 2a″ × b″ × 4c″ cell for the chain-slid model or in between the corresponding planes for the parallel-set and sheet-slid/contracted models. However, the detailed structure of FB in the complex is not yet determined due to the low crystallinity of the complexes.
Tài liệu tham khảo
Brown RM (1996) The biosynthesis of cellulose. J Macromol Sic Pure Appl Chem A33:1345–1373. Related references are therein
Cousin SK, Brown RMJ (1997a) X-ray diffraction and ultrastructural analyses of dye-altered celluloses support van der Waals forces as the initial step in cellulose crystallization. Polymer 38:897–902
Cousin SK, Brown RMJ (1997b) Photoisomerization of a dye-altered β-1,4 glucan sheet induces the crystallization of a cellulose-composite. Polymer 38:903–912
Haigler HC, Benziman M (1982) Biogenesis of cellulose I microfibrils occurs by cell-directed self-assembly in Acetobacter xylinum. In: Brown RM (ed) Cellulose and other natural polymer systems. Biogenesis, structure, and degradation. Plenum Press, New York and London, pp 273–297. Related references are therein
Haigler CH, Chanzy H (1988) Electron diffraction analysis of the altered cellulose synthesized by Acetobacter xylinum in the presence of fluorescent brightening agents and direct dyes. J Ultrastruct Mol Struct 98:299
Haigler CH, Brown RMJ, Benziman M (1980) Calcofluor white ST alters the in vivo assembly of cellulose microfibrils. Science 210:903–905
Hestrin S, Schramm M (1954) Synthesis of cellulose by Acetobacter xylinum. Biochem J 58:345–352
Kai A (1984a) The structure of the nascent fibril produced by Acetobacter xylinum: The x-ray diffraction diagram of cellulose produced in the presence of a fluorescent brightener. Makromol Chem Rapid Commun 5:307–310
Kai A (1984b) The structure of the nascent fibril produced by Acetobacter xylinium: the lattice spacing of cellulose produced in the presence of a fluorescent brightener. Makromol Chem Rapid Commun 5:653–655
Kai A, Xu P (1990) Structure of bacterial cellulose-brightener complex from aspect of behavior of its mercerization. Polym J 22:955–961
Kai A, Xu P (1991) Orientation of crystallites in the bacterial cellulose-fluorescent brightener complex membrane. Kobunshi Ronbunshu 48:449–452
Kai A, Xu P, Horii F, Hu S (1994) CP/MAS 13C NMR study on microbial cellulose-fluorescent brightener complexes. Polymer 35:75–79
Nishiyama Y, Langan P, Chanzy H (2002) Crystal structure and hydrogen-bonding system in cellulose I β from synchrotron X-ray and neutron fiber diffraction. J Am Chem Soc 124:9074–9082
Nishiyama Y, Sugiyama J, Chanzy H, Langan P (2003) Crystal structure and hydrogen bonding system in cellulose I α from synchrotron X-ray and neutron fiber diffraction. J Am Chem Soc 125:14300–14306
Suzuki S, Hirai A, Horii, F (2010) Structural changes of sub-elementary fibrils of bacterial cellulose in the isolation process. Prepr 17th Ann Meet Cellulose Soc Japan, pp 25–26
Suzuki S, Suzuki F, Kanie Y, Tsujitani K, Hirai A, Kaji H, Horii F (2012) Structure and crystallization of sub-elementary fibrils of bacterial cellulose isolated by using a fluorescent brightening agent. Cellulose 19:713–727