Nonenzymatic Hydrogen Peroxide Detection Using Surface-Enhanced Raman Scattering of Gold–Silver Core–Shell-Assembled Silica Nanostructures

Hydrogen peroxide (H(2)O(2)) plays important roles in cellular signaling and in industry. Thus, the accurate detection of H(2)O(2) is critical for its application. Unfortunately, the direct detection of H(2)O(2) by surface-enhanced Raman spectroscopy (SERS) is not possible because of its low Raman cross section. Therefore, the detection of H(2)O(2) via the presence of an intermediary such as 3,3,5,5-tetramethylbenzidine (TMB) has recently been developed. In this study, the peroxidase-mimicking activity of gold–silver core–shell-assembled silica nanostructures (SiO(2)@Au@Ag alloy NPs) in the presence of TMB was investigated using SERS for detecting H(2)O(2). In the presence of H(2)O(2), the SiO(2)@Au@Ag alloy catalyzed the conversion of TMB to oxidized TMB, which was absorbed onto the surface of the SiO(2)@Au@Ag alloy. The SERS characteristics of the alloy in the TMB–H(2)O(2) mixture were investigated. The evaluation of the SERS band to determine the H(2)O(2) level utilized the SERS intensity of oxidized TMB bands. Moreover, the optimal conditions for H(2)O(2) detection using SiO(2)@Au@Ag alloy included incubating 20 µg/mL SiO(2)@Au@Ag alloy NPs with 0.8 mM TMB for 15 min and measuring the Raman signal at 400 µg/mL SiO(2)@Au@Ag alloy NPs.