Synthesis of Chitosan-Stabilized Silver Nanoparticles under In Situ and Ex-Situ Conditions and Their Biological Applications

Silver nanoparticles were obtained in the presence of 2-propanol under both in situ and ex situ conditions. It was established that the hydrodynamic radius and polydispersity of the particles increase with rising pH (6.0–11.0) due to the accelerated reduction of Ag+ ions. Variation of the chitosan molecular-weight parameters and the chitosan/Ag+ molar ratio (5–30) enabled controlled formation of stabilized nanoparticles ranging from 20 to 140 nm. The chitosan–silver nanoparticle dispersions in 0.2–0.5% aqueous acetic solutions demonstrated pronounced fungicidal activity against Fusarium solani 169, Fusarium oxysporum 280, and Verticillium dahliae 57, producing sterile zones of 31–34 mm.