Efficient reduction of Toluidine Blue O dye using silver nanoparticles synthesized by low molecular weight chitosans

The aim of this paper is to study the catalytic behaviour of silver nanoparticles (AgNps) produced using low molecular weight chitosan (LMWC) samples depolymerized by an enzymatic method, using either lysozyme or chitosanase. The ability of four sets of silver nanoparticles to reduce Toluidine Blue (TBO) was used as test reaction, and the effect of both catalyst concentration and reaction temperature on the effectiveness of the catalytic reduction was assessed. Generally speaking, AgNps produced through chitosan depolymerization with lysozyme showed better performance than those ones produced using chitosanase. On the other hand, colloidal silver nanoparticles stabilized with LMWC were mixed with medium molecular weight chitosan (MMWC) sample, in order to generate different scaffolds by using beta-glycerol phosphate. These scaffolds were analyzed by microscopy, XRD, ATR-FTIR, and their swelling capacity was evaluated. Their catalytic ability for reducing TBO, as well as their reusability, was assessed. Our results showed that the catalytic properties of the colloidal AgNps were remarkably affected by the properties of the LMWC used for their synthesis. Once again, AgNps-chitosan scaffolds produced with chitosan depolymerized with lysozyme were more effective.