Antioxidant properties of gold nanoparticles studied by ESR spectroscopy

The Au-containing nanocomposites were synthesized by UV irradiation followed by the thermal treatment of chitosan oligomer solutions doped by HAuCl4. The size oft he formed gold nanoparticles depends on the concentration of the dopant, which is proved by UV-Vis absorption spectroscopy and small-angle X-ray scattering (SAXS). The antioxidant activity of the gold nanoparticles with respect to hydroxy radicals significantly depends on the specific surface of the particles, which was found using the secondary radical spin-trapping technique. The change in the (OH)-O-center dot radical concentration was monitored by the intensity of the ESR signal of the adduct of the spin trap (alpha-phenyl-N-tert-butylnitrone) with the Me-center dot radicals formed in the reaction of (OH)-O-center dot with DMSO.