Development of Methodology Based on the Formation Process of Gold Nanoshells for Detecting Hydrogen Peroxide Scavenging Activity

In the present work, we have developed a novel nanocomposite-based method for estimating antioxidant activity. The assay implements a new enzyme-free optical nanoprobe for assessing hydrogen peroxide (H2O2) scavenging activity based on the formation process of gold nanoshells (GNSs). H2O2 could enlarge the gold nanoparticles (GNPs) on the surface of GNSs precursor nanocomposites (SiO2/GNPs), and the preadsorbed GNPs served as nucleation sites for Au deposition. As the concentration of H2O2 increases, more GNPs on the SiO2 cores are enlarged until continuous GNSs are formed. During the growth procedure, the spectra changes correlate well with H2O2 concentrations which indicate that this nanocomposite is a good nanoprobe for detecting H2O2. H2O2 scavenging activities of several antioxidants were determined by restraining the H2O2-mediated formation of GNSs from SiO2/GNPs, and the changes of the corresponding plasmon absorption bands correlated well with H2O2 scavenging activity of antioxidants. The spectra were monitored by a IN-vis-near-infrared (NIR) spectrophotometer, and the wavelength changes were adopted as detection signal. The results obtained expressed the difference of H2O2 scavenging activity between various tested compounds, and the relationship between function and structure of antioxidants was also discussed in this article. The new method based on the formation process of GNSs is simple, rapid, and sensitive and, additionally, can be used in visual analysis to a certian extent for antioxidant functional evaluation.