Nanoparticle-based assays of antioxidant activity.

The antioxidant power of several phenolic acids and related food samples is estimated from the generation and growth of gold nanoparticles. The intensity of the resulting particle plasmon absorption bands correlates well with the redox characteristics of these phenolic acids estimated from cyclic voltammetry experiments. The highest capacity of reducing gold(III) to gold nanoparticles corresponds to the highest antioxidant activity, consistent with the tendency of phenolic acids to donate electrons.