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 (H(2)O(2)) scavenging activity based on the formation process of gold nanoshells (GNSs). H(2)O(2) could enlarge the gold nanoparticles (GNPs) on the surface of GNSs precursor nanocomposites (SiO(2)/GNPs), and the preadsorbed GNPs served as nucleation sites for Au deposition. As the concentration of H(2)O(2) increases, more GNPs on the SiO(2) cores are enlarged until continuous GNSs are formed. During the growth procedure, the spectra changes correlate well with H(2)O(2) concentrations which indicate that this nanocomposite is a good nanoprobe for detecting H(2)O(2). H(2)O(2) scavenging activities of several antioxidants were determined by restraining the H(2)O(2)-mediated formation of GNSs from SiO(2)/GNPs, and the changes of the corresponding plasmon absorption bands correlated well with H(2)O(2) scavenging activity of antioxidants. The spectra were monitored by a UV-vis-near-infrared (NIR) spectrophotometer, and the wavelength changes were adopted as detection signal. The results obtained expressed the difference of H(2)O(2) 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 certain extent for antioxidant functional evaluation.