The effect of polymeric stabilizers on the catalytic activity of Pt nanoparticles for an electron-transfer reaction between Fe(CN)(6)(3-) and S2O32- was investigated. Pt nanoparticles were prepared by laser ablation of Pt plate in water, and then stabilized with typical stabilizing polymers such as poly(vinyl pyrrolidone) (PVP), poly(vinyl sulfate) (PVS), and polyethyleneimine (PEI). The catalytic reaction proceeds much faster with PEI-stabilized nanoparticles than PVP- or PVS-stabilized particles. The activity of nanoparticles also highly depends on pH and polymer concentration. These clearly demonstrate that the net charge of the stabilizers plays a decisive role for the nanoparticle-mediated electron transfer between charged reactants. (C) 2009 Elsevier B. V. All rights reserved.