Kinetics and mechanisms of depolymerization of alginate and chitosan in aqueous solution.

The kinetics and mechanisms of depolymerization of aqueous chitosan and alginate solutions at elevated temperatures have been investigated. Chitosan salts of different degree of acetylation (FA), type of counterions (-glutamate, -chloride) and degree of purity were studied. One commercially available highly purified sodium alginate sample with high content of guluronic acid (G) was also studied.

Stability of lead(II) complexes of alginate oligomers.

The current work reports on the Pb(ll) complexes formed with oligomeric uronic acids (carboxylated saccharide residues) found polymerized in the cell walls and envelopes of algae and bacteria alike. The application of partial acid hydrolysis, size-exclusion chromatography (SEC), 1H NMR, and scanned deposition stripping chronopotentiometry (SSCP) has permitted the determination of stability constants for Pb(II) with both mannuronic (M) and guluronic (G) acid oligomers ranging from the dimer to the pentamer. The determined logarithm of the stability constants range between 4.

Transepithelial transport of morphine and mannitol in Caco-2 cells: the influence of chitosans of different molecular weights and degrees of acetylation.

The object of this study was to compare the effect of chitosans of different number-average molecular weights (MWs) and degrees of acetylation (F(A)) on transepithelial transport of morphine in Caco-2 cells. Caco-2 monolayers on polycarbonate (PC) membranes (0.5 cm(2)) were incubated with morphine (10 microM) or mannitol (55 microM) for 180 min.

Mucous systems show a novel mechanical response to applied deformation.

Mucous secretions have a wide range of biological functions that are intimately linked with their rheological properties. In addition, many mucous secretions are exposed to significant stress and deformation during physiological function. This study has examined the rheological response of three mucous systems, native pig gastric mucus, purified mucin gels, and mucin alginate gels, to increasing applied stress to a level sufficient to induce flow behavior.