Two salts of the biopolymer chitosan were prepared in aqueous medium by employing an excess of HCl or HNO3 in order to ensure neutralization of all NH2-chitosan groups. Chitosan salts were extensively dialyzed in dionised water and dried at 40 ºC until film formation. The films were characterized by thermogravimetry, FTIR and conductimetric tritration. QH+Cl− and QH+NO3− salts were viscosimetrically evaluated in free acid aqueous solutions in the presence of NaCl to control ionic strength of the medium. Unexpected high intrinsic viscosity values were obtained at low ionic strength when QH+NO3− salt were evaluated. Smidsrod´s approach was employed to estimate the stiffness parameter of both salts and B = 0.084 and 0.120 for QH+Cl− and QH+NO3−, respectively, were obtained.
New types of polysaccharidic assemblies based on chitosan and uncharged or charged derivatives of scleroglucan are presented. Macroscopic assemblies having a spherical skinlike shape were prepared by controlled mixing of two polyelectrolyte solutions. Hydrogels based exclusively on the above natural derivatized polysaccharides crosslinked via simple chemical processes, avoiding the use of extraneous reticulating agents and organic solvents, are also described. These biocompatible materials may, eventually, be used in drug release formulations or for the incapsulation of bioactive macromolecules. The interesting possibility exists to study the micelle formation of amphiphiles within the spherical skins.
Morphological studies of bacterial strains Micromorphological study: Consisted in evaluation of cell motility and shape by observation under the optical microscope and determination of the biochemical nature of the bacterial wall (Gram staining). 12 Macromorphological study: The macroscopic characteristics of the colonies such as color, shape, texture and appearance, as well as the production of pigments, were observed after 24 hours of incubation of isolates cultured on brain heart infusion (BHI) agar at 30°C. 13 Biochemical characterization A preliminary taxonomic location at the group or family level was performed using the following biochemical tests: Hugh and Leifson medium, nitrate reduction, MIO (Motility, Indol, Ornithine), oxidase test, MacConkey Agar, and urea hydrolysis, according to procedures previously described. 12-14
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