Growth-sensitive 3D ordered gold nanoshells precursor composite arrays as SERS nanoprobes for assessing hydrogen peroxide scavenging activity

A novel method based on surface-enhanced Raman scattering (SERS) was developed to estimate the antioxidant activity of antioxidants by using self-assembled three-dimensionally (3D) ordered gold nanoparticles (GNPs) precursor composite (SiO2/GNPs) arrays as nanoprobes. H2O2 could reduce AuCl4- to Au-0 which deposited onto the surface of the SiO2/GNPs arrays and enlarged the GNPs. As the concentration of H2O2 increased, the surface coverage of the resultant gold on the silica cores increased accordingly until continuous gold nanoshells (GNSs) were formed. The change of the intensities of the SERS spectra correlated well with H2O2 concentration which indicated that this SiO2/GNPs array was a potential SERS nanoprobe for H2O2. The presence of antioxidant will prevent the growth of GNPs on the surface of the silica arrays from forming the structure which has strongest SERS-activity and the corresponding change in SERS intensity correlated well with the H2O2 scavenging activity of the antioxidants. The H2O2 scavenging activities of four plant-based antioxidants, tannic acid, citric acid, ferulic acid, and tartaric acid were studied. Our results showed the H2O2 scavenging activities (SAHP values) of these four compounds were: tannic acid > ferulic acid > citric acid > tartaric acid.