Aggregates of gold nanoparticles (AuNPs) that mediate the assembly of manganese dioxide nanoparticles (nano-MnO2) for hydrogen peroxide (H2O2) amperometric sensing have been developed. The aggregates were prepared by directly mixing citric-capped AuNPs and poly(allylamine hydrochloride) (PAH)-capped nano-MnO2 using an electrostatic self-assembly strategy. The prepared sensor exhibited excellent electrochemical behaviors and a wide linear range from 7.80 x 10(-7) to 8.36 x 10(-4) M with a detection limit of 4.68 x 10(-8) M (S/N = 3) because of the synergistic influence of excellent catalytic ability of MnO2 and good electrical conductivity of AuNPs. In addition, its applicability to practical samples for measuring H2O2 in toothpastes has obtained a satisfactory result. Due to the ease of preparation and excellent properties of the sensor, indicating the MnO2-AuNP material may be a potential H2O2 sensor. (C) 2010 Elsevier Ltd. All rights reserved.