OH-Radical-induced chain scission of chitosan in the absence and presence of dioxygen

Hydroxyl radical-induced crosslinking and radiation-initiated hydrogel formation in dilute aqueous solutions of carboxymethylcellulose

“…Generally, irradiation of polysaccharides induces their degradation, resulting in chains of reduced molecular weight, and no crosslinked structures are formed (Czechowska-Biskup et al, 2007;Ershov, 1998;Ulanski & von Sonntag, 2000;Wasikiewicz, Yoshii, Nagasawa, Wach, & Mitomo, 2005;Zegota & von Sonntag, 1977). Some methods have been elaborated to crosslink polysaccharides by ionizing radiation by using an additive to promote crosslinking process, such as an alkyne gas (Al-Assaf, Phillips, Williams, & Plessis, 2007;Phillips, Plessis, Al-Assaf, & Williams, 2003) or carbon tetrachloride (Ramnani, Chaudhari, Patil, & Sabharwal, 2004).…”

Metal-coordinating controlled oxidative degradation of chitosan and antioxidant activity of chitosan-metal complex

“…Enzymatic degradation (such as chitosanase, lipase, proteinase, polysaccharase), physical degradation (by X-ray, light, microwave), chemical methods, including acidic hydrolysis with some inorganic acid (such as HCl, HF, H 2 SO 4 , H 3 PO 4 , HNO 2 ) or some organic acid (such as HOAc, formic acid) and oxidative hydrolysis with oxidant (such as H 2 O 2 , O 3 , CH 3 COOOH), are the usual methods for chitosan degradation. [8][9][10][11][12][13][14][15][16] Except degradation with chitosanase, which can get chitosan oligomer with 6-8 glucose residues, other methods often produce the low molecular weight chitosan with large molecular weight distribution, and so the yield of low molecular weight chitosan with particular molecular weight is low. In addition, the degradation with chitosanase has some other restrictions, such as, the loss of chitosanase activity, difficult product separation, and so on.…”

Improving the hydrogen peroxide bleaching efficiency of aspen chemithermomechanical pulp by using chitosan

“…This improvement may be due to the formation of hydroxyl radicals catalyzed by Cu(II)-chitosan, which enhances the oxidation ability of hydrogen peroxide (Šuláková, Hrdina, & Soares, 2007). In addition, the hydroxyl radicals could induce the chain scission of chitosan (Ulanski & Von Sonntag, 2000). The foregoing results indicate that chitosan could inhibit the decomposition of hydrogen peroxide catalyzed by transition metals and improve the hydrogen peroxide bleaching efficiency of CTMP.…”