Acid hydrolysis of commercial chitosans

Abstract

Commercial chitosans were subjected to controlled acid hydrolysis and their degrees of deacetylation (DD), molecular size and rheological flow profiles determined (pre-and post-hydrolysis) by 1 H-NMR spectroscopy, high-performance size-exclusion chromatography and rheometry, respectively. Hydrolysis resulted in DD increases between 4 and 11%. Unhydrolysed chitosans had M w and M n values in the ranges 700-1200 and 130-210 kDa, respectively. Chitosan with the smallest initial molecular size averages had the smallest averages after hydrolysis; however, a chitosan with an intermediate initial molecular size proved to be most resistant to hydrolysis. Molecular size trends were paralleled by zero shear viscosity (η 0 ) measurements determined by application of the Williamson model to rheological flow profile data. Viscosity is obviously related to molecular size, but does not necessarily reflect relative ease of hydrolysis, since specific hydrolysis conditions affect structurally similar polysaccharides in different ways (in terms of rate of depolymerisation and de-N-acetylation, etc), which are not simply due to differences in molecular size profiles pre-hydrolysis.

Preparation of alginate–chitosan fibers with potential biomedical applications

“…With longer retention times in the coagulation bath,chitosan was ableto penetrate more 321 into the gelled alginate fibers. The amount of chitosan incorporated into the fibers agrees with 322 the reported literature(Knill et al, 2004).323 324…”

Influence of the Chemical Structure and Physicochemical Properties of Chitin- and Chitosan-Based Materials on Their Biomedical Activity

“…• SEC-RI (pullulan calibration) (Hasegawa et al, 1994;Knill et al, 2005;Lin & Lin, 2003) • SEC-LALS (Kubota et al, 2000;Ottøy et al, 1996Ottøy et al, , 1995 • SEC-MALS (Tømmeraas et al, 2002;Sorlier et al, 2001;Sorlier, 2002;Berth et al, 1998;Lamarque et al, 2004Lamarque et al, , 2005Schatz et al, 2003;Brugnerotto et al, 2001) • SEC-LALS-Vis (Weinhold et al, 2009) • SEC-MALS-Vis (Christensen et al, 2008) Since the use of size-exclusion chromatography is commonly agreed upon, more controversy is present about surrounds the different detectors used online for chromatography. Nowadays, all the old bench methods can be applied to a chromatography setup such as a refractive index detector (RI), viscosity detector (Vis) and light-scattering detectors (single-90°, low-angle and 90° (LALS), or multi-angle with 3, 5, or up to 18 angles (MALS).…”

Determinación De La Concentración De Quitosano en Polvo Por Viscosimetría Capilar

“…Este efecto depende de la concentración del polímero y la naturaleza del solvente. El agua permite que la macromolécula pueda hallarse desenrollada y alargada; es decir, es capaz de extender las cadenas lineales, así como desagregar 6,7,8 dichas cadenas.…”