title: Molecular weight effect on liquid crystalline gel formation of curdlan.
abstract: Curdlan dissolved in alkaline solution forms a unique gel consisting of liquid crystalline gel (LCG) and amorphous gel (AG) in alternating layers by a dialysis into aqueous calcium chloride. The unique structure has been investigated by measuring the birefringence of the gel Deltan, the ratio q of the thickness of LCG layer delta to the gel radius R, and the calcium content in the gel C(Ca) in a wide range of molecular weights of fractionated Curdlan, as well as unfractionated Curdlan as a control. With increasing molecular weight of Curdlan, Deltan increased and q = delta/R decreased, and both became saturated at high molecular weight. Deltan and q for unfractionated Curdlan were smaller and larger, respectively, than those for fractionated Curdlan. C(Ca) was constant irrespective of molecular weight and its distribution, which means that the abundance of calcium ions per glucose unit in the gel does not depend on the degree of orientation of mesogens. These results suggest that the amorphous phase appears when the size of the Curdlan molecules is larger than the average intermolecular distance, resulting from the random coil to triple helix transformation of Curdlan molecules associated with lowering hydroxide anion concentration in the dialysis process.
authors.affiliation: Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nobe
authors.forename: Naomi
authors.initials: N
authors.lastname: Kuroda
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Dobashi
authors.forename: Takao
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Akira
authors.initials: A
authors.lastname: Konno
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Nakata
mesh_terms: D000838:Anions; D001672:Biocompatible Materials / Q000737:chemistry*; D055592:Biophysical Phenomena; D001703:Biophysics; D002118:Calcium / Q000737:chemistry; D002122:Calcium Chloride / Q000737:chemistry; D002412:Cations; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D004548:Elasticity; D005782:Gels; D005936:Glucans / Q000737:chemistry; D006878:Hydroxides / Q000737:chemistry; D050866:Liquid Crystals; D046911:Macromolecular Substances / Q000737:chemistry*; D008968:Molecular Conformation; D008970:Molecular Weight; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D013535:Suspensions; D014867:Water / Q000737:chemistry; D047071:beta-Glucans / Q000737:chemistry*
chemical_list: D000838:Anions; D001672:Biocompatible Materials; D002412:Cations; D003692:Delayed-Action Preparations; D005782:Gels; D005936:Glucans; D006878:Hydroxides; D046911:Macromolecular Substances; D011135:Polysaccharides, Bacterial; D012996:Solutions; D013535:Suspensions; D047071:beta-Glucans; D014867:Water; C038459:curdlan; D002122:Calcium Chloride; D002118:Calcium