(SPR) peak shift (�A) reached the maximum. Thus, the acetate buffer with pH 5.4 is taken as the optimal reaction solution. Inaddition, a temperature-dependent assay was also performed in our experiment. The �A increased with the reaction temperature and began to level off beyond 40 ◦C. Thus, 40 ◦C was chosen as the optimal reaction temperature. The effect of the reaction time of the Ag nanoplates and H2O2 was investigated. The �A reached the maximum within 40 min, and thus we chose 40 min of incubation for H2O2 measurements in the following experiments. We further investigated the effect of the initial amount of the trianglular Ag nanoplates on the color intensity. When the concentration of the colloidal Ag was 88.6 �M, the color of the Ag nanoplates was deep blue, and the color intensity was the strongest.