Polyol synthesis of silver nanoparticles: mechanism of reduction by alditol bearing polysaccharides.

Alditol bearing chitosans have shown the ability to reduce silver ions in mild conditions and without addition of exogenous reducing agents. The ion reduction induces the formation of a lactone moiety on the polysaccharide (Fetizon reaction) without causing C-C bond cleavage on the polyol. The close and multivalent arrangement of the endogenous reducing agent (alditols) on the polysaccharide backbone resulted in the formation of silver nanoparticles (phi < 10 nm), which induced a considerable SERS effect and led to hydrogel formation.