Core-to-Shell Thickness-Regulated Ag@Au Nanocatalyst for LSPR-Improved <i>In Situ</i> Detection of Extracellular Peroxide: Response in a Cancer Cell

In the current study, we designed a unique core-to-shell thickness-regulated Ag@Au nanocatalyst (_CSNPs) for H₂O₂-induced selective oxidative etching of core silver. Synthesized _CSNPs exhibit high colloidal stability and demonstrate a significant localized surface plasmon resonance (LSPR) effect in the biological window. These unique properties in turn allow us to formulate a unique _CSNP-based LSPR-induced electrochemical detection assay for selective trace-level sensing of H₂O₂ <i>in vitro</i>. Conceptually, we utilized LSPR to amplify the electrochemical signals by inducing the generation of hot electrons and hot holes, which can be harnessed for catalytic purposes. Here, the Au shell acts as a supplier of the hot electron for enhanced catalytic reduction of H₂O₂ where the free electron of the Au shell is subsidized by the Ag core by its subsequent oxidation. The combination of high LSPR property, stability, and efficient binding property makes these NPs not only a surface-enhanced Raman scattering (SERS) enhancer but also a promising electrocatalyst for biomolecule detection, which emphasizes the significant potential of these engineered nanomaterials in various applications.