A facile SERS strategy to detect glucose utilizing tandem enzyme activities of Au@Ag nanoparticles

Surface-Enhanced Raman Scattering (SERS) is a powerful analysis technology, attracting more and more attention due to its high sensitivity and selectivity. Herein, we report a simple seed-mediated method to synthesize [email protected] nanoparticles (NPs) as a multifunctional biosensor for the label-free detection of hydrogen peroxide (H2O2) and glucose by SERS. [email protected] NPs, as an ultrasensitive SERS substrate, show the dual activities (peroxidase-like and GOx-like activities). Under the condition of pH 4.0 NaAc buffer solution, the glucose and H2O can be catalyzed by [email protected] NPs to produce glucose acid and H2O2, and then H2O2 can oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to form a blue oxidation product oxidic TMB (oxTMB) which exhibits strong SERS signals at 1188, 1330, 1605 cm−1. Thus, we have developed a new SERS strategy for analysis of glucose with a detection limit of 5 × 10−10 mol L−1, suggesting that [email protected] NPs have the potential for biosensor, immunoassay and medical treatment.