Antioxidant-potentiality of gold-chitosan nanocomposites

Gold nanoparticles were prepared in the presence of chitosan via reduction of HAuCl4 with sodium borohydride. The average particle size of gold nanoparticles was significantly affected with the concentration of chitosan added and was ranged between 6 and 16 nm. The gold-chitosan nanocomposites are formed by adsorbing chitosan molecules on the gold nanoparticles. The catalytic activity of gold-chitosan nanocomposites upon elimination of hydroxyl radicals formed in an H2O2/FeSO4 system was examined using a spin-trapping method. The catalytic activity increased with the concentration of chitosan added and showed a maximum and then decreased with a further concentration of chitosan added, although a strict correlation between the average diameter of gold and the catalytic activity was not found. In addition, the activity of gold-chitosan was 80 times higher than that of ascorbic acid, which is well known as an antioxidant. (C) 2003 Elsevier B.V. All rights reserved.