Platinum nanoparticle is a useful scavenger of superoxide anion and hydrogen peroxide

Bimetallic nanoparticles consisting of gold and platinum were prepared by a citrate reduction method and complementarily stabilized with pectin (CP-Au/Pt). The percent mole ratio of platinum was varied from 0 to 100%. The CP-Au/Pt were alloy-structured. They were well dispersed in water. The average diameter of platinum nanoparticles (CP-Pt) was 4.7 +/- 1.5 nm. Hydrogen peroxide (H2O2) was quenched by CP-Au/Pt consisting of more than 50% platinum whereas superoxide anion radical (O-2(-)) was quenched by any CP-Au/Pt. The CP-Au/Pt quenched these two reactive oxygen species in dose-dependent manners. The CP-Pt is the strongest quencher. The CP-Pt decomposed H2O2 and consequently generated O-2 like catalase. The CP-Pt actually quenched O-2,(-) which was verified by a superoxide dismutase (SOD) assay kit. This quenching activity against O-2(-) persisted like SOD. Taken together, CP-Pt may be a SOD/catalase mimetic which is useful for medical treatment of oxidative stress diseases.