Urea/NaOH aqueous solution as new solvent of aeromonas gum

Abstract

Aeromonas (A) gum, an acidic heteropolysaccharide, formed aggregates easily in NaCl aqueous solution. A novel solvent of the A gum, which can prevent aggregation, was found to be 0.20M urea/0.25M NaOH aqueous solution. The weight-average molecular weight (M w ), radius of gyration (͗s 2 ͘ 1/2 ), and intrinsic viscosity ([]) of the samples were determined in 0.20M urea/0.25M NaOH aqueous solution at 25°C by light scattering (M w , ͗s 2 ͘ 1/2 ) and viscometry ([]). The values of M w , ͗s 2 ͘ 1/2 , and [] were close to those in 0.20M lithium chloride/dimethylsulfoxide, in which the A gum exists as a semiflexible single chain, implying the same conformation for the A gum in 0.20M urea/0.25M NaOH aqueous solution. The results revealed that 0.20M urea/0.25M NaOH aqueous solution is a good solvent, which effectively avoids the aggregates of the A gum in aqueous solution. Moreover, it can be used to investigate the solution properties and chain conformation of water-insoluble polysaccharides or the polysaccharides that are easily aggregated in aqueous systems.

Dissolution and stability of chitosan in a sodium hydroxide/urea aqueous solution

“…Sodium hydroxide/urea aqueous solutions have been used to dissolve biomacromolecules, with their composition and the procedure used affecting their solubility. 9,17 In this study, we chose a freeze-thaw treatment to destroy the particle structure and allow the solvent to penetrate to the inner part of the particles. The solubility of chitosan MMWC after four cycles of freeze-thaw treatments was determined to select the appropriate solvent composition for further experiments.…”

“…Sodium hydroxide/urea aqueous solutions have been used to dissolve biomacromolecules, with their composition and the procedure used affecting their solubility . In this study, we chose a freeze–thaw treatment to destroy the particle structure and allow the solvent to penetrate to the inner part of the particles.…”

Impact of urea on the three-dimensional structure, viscoelastic and thermal behavior of iota-carrageenan

“…In the case of polysaccharides higher amounts of urea thwart gelation in amylose (Welsh, Bailey, Chandarana & Norris, 1982), xanthan (Dintzis, Babcock & Tobin, 1970; Frangou, Morris, Rees, Richardson & Rossmurphy, 1982), iota-carrageenan (Morris & Belton, 1982), kappa-carrageenan (Nishinari, Watase, Williams & Phillips, 1990) and agarose (Watase & Nishinari, 1986). However, urea in association with sodium hydroxide is reported to be beneficial for studying the functional behaviors of water insoluble cellulose (Cai & Zhang, 2006) and chitosan (Tsaih & Chen, 1997) as well as those of water soluble glucan (Zhang, Zhang & Cheng, 2000) and aeromoans gum (Xu, Zhang & Zhang, 2005) aggregates.…”