Raman spectroscopy for scavenging activity assay using nanoshell precursor nanocomposites as SERSprobes

In this work, we have developed a novel SERS-based approach to detect hydrogen peroxide (H2O2) scavenging activity by using gold nanoshell precursor nanocomposites (SiO2/GNPs) as nanoprobes. H2O2 can reduce AuCl4- to Au0 and enlarge the gold nanoparticles (GNPs) that attached on the surface of SiO2. As the concentration of H2O2 increases, the surface coverage of resultant gold on silica cores increases accordingly until continuous gold nanoshells (GNSs) are formed. During the growth process, there is a strong correlation between the SERS-activity of the GNSs and the amount of H2O2 that is used as reductant. When H2O2 reaches 250 μM, the resultant GNSs show the highest SERS-activity. H2O2 can be scavenged by antioxidants such as tannic acid and L-apple acid. Their H2O2 scavenging activities were determined by restraining the H2O2-mediated (250 μM) growth of SiO2/GNPs. The decrease of the SERS-activity was proportional to the H2O2 scavenging activity of the antioxidant. The results showed that tannic acid had a much higher H2O2 scavenging activity than that of L-apple acid.