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Using mulberry silkworm pupae as an alternative source of renewable raw materials, a water-soluble Bombyx mori chitosan derivative N-carboxymethylchitosan is synthesized. A method for the photochemical reduction of silver ions into silver nanoparticles in an N-carboxymethylchitosan matrix is developed. The presence of silver nanoparticles in a colloidal solution is confirmed by UV spectroscopy, and their shape and size are determined by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

A method for the preparation of a pure colloidal solution of silver (silver hydrosol) containing only small metal nanoparticles and carbonate ions stabilizing them was developed. For this purpose, a solution containing silver and oxalic acid salts was exposed to UV radiation of a low-pressure pulsed xenon lamp. The irradiation initiated Ag+ reduction with oxalate ions to give metal nanoparticles and carbonate ions. The latter ensure the electrostatic protection of nanoparticles via the formation of an electric double layer. Variation of the process conditions (silver and oxalate concentrations, UV irradiation conditions, the presence of air, and so on) allows the preparation of silver hydrosols with nanoparticle size ranging from 5 to 30 nm. The hydrosol is aggregatively stable for several months. [ABSTRACT FROM AUTHOR]

The correlation between the chemical nature of capping agents used to prepare colloidal silver dispersions and kinetic characteristics of the process of oxidation of the dispersed phase (spherical silver nanoparticles, 2–50 nm in diameter) by hydrogen peroxide was studied for the first time. The well-pronounced correlation between the oxidative dissolution rate and the biological activity of silver dispersions was revealed with respect to the inhibition of the growth of the Saccharomyces cerevisiae yeast. The biological activity of nanosilver dispersions was found to be primarily controlled by the rate of generation of silver ions while the chemical nature of the capping agent defined the rate of generation of silver ions, thus showing an effective way to control the biological action of medications based on silver nanoparticles by varying the nature of the capping agent. [ABSTRACT FROM AUTHOR]