DECOMPOSITION PROFILES OF SILVER NANOPLATES UNDER OXIDATIVE CONDITIONS USING HYDROGEN PEROXIDE

Abstract

Silver nanoparticles (AgNPs) have been widely used nowadays due to their unique optical properties and potential applications. In this study, the decomposition profiles of silver nanoplates (AgNPls) under oxidative conditions using hydrogen peroxide (H2O2) were investigated. The AgNPls were morphologically decomposed by a low concentration of H2O2 revealed by UV-visible absorption spectroscopy and transmission electron microscopy (TEM). The morphological changes of AgNPls can be observed by the localized surface plasmon resonances (LSPR) in UV-visible spectrum. After incubating AgNPls with various concentrations of H2O2 and monitoring for 60 minutes, the in-plane dipole LSPR peak, which is related to the lateral size of AgNPls, was decreased and blue-shifted. The out-of-plane quadrupole LSPR, which is related to the aspect ratio (lateral size/thickness) of AgNPls, was decreased and slightly red-shifted. This observation indicates the AgNPls were immediately converted from regular disk into smaller and rounder disk after H2O2 were added. The morphology changes of AgNPls led to an appreciable color change in the AgNPl solution from red to pink, orange, yellow and finally transparency due to the H2O2 concentration. Furthermore, a good linear relationship between the wavelength shifts (Dl) of AgNPls and the H2O2 concentration can be obtained. The solution phase detection of H2O2 by the direct morphological change can be accomplished without any surface modification of AgNPls. Therefore, a new and simple colorimetric strategy based on the chromaticity analysis of AgNPl solution was demonstrated. The hydrogen peroxide concentration at 1.57 micromolar can be recognized by naked-eye observation with good accuracy, stability and reproducibility. In addition, the proposed protocol can be applied to determine the glucose concentration through the glucose-oxidase system. The new colorimetric determination of hydrogen peroxide utilizing digital image analysis on color changes from AgNPl shape decomposition will open up an alternative method for simple, rapid and reliable detection of hydrogen peroxide and can realize its future applications in biochemical analysis or clinical diagnosis.