Core–shell Fructus Broussonetia-like Au@Ag@Pt nanoparticles as highly efficient peroxidase mimetics for supersensitive resonance-enhanced Raman sensing

摘要

We herein present a simple and surfactant-free synthetic strategy for the preparation of corea€“shell Fructus Broussonetia-like Au@Ag@Pt nanoparticles (FBNPs) via a combination of galvanic replacement and reagent reduction, in which a chitosan (CS)-mediated epitaxial growth of Pt multi-branches occurs on cresyl violet labeled Au corea€“Ag shell nanoparticles (NPs) at room temperature. The as-prepared novel nanostructures exhibit an enzyme mimetic activity due to the formation of a Fructus Broussonetia-shaped Pt shell, the absence of surfactants and the positively charged CS molecules intertwined within the outermost Pt NPs. Relying on the high sensitivity of resonance-enhanced Raman scattering and the highly efficient intrinsic peroxidase-like activity of FBNPs, H2O2 was detected with a wide detection window from 10 pM to 100 ??M when utilizing 3,3a€2,5,5a€2-tetramethylbenzidine (TMB) as the substrate. Based on the H2O2a€“TMB catalytic oxidation system a simple, sensitive, selective and universal platform has been extended for the detection of all peroxidase-related analytes. For example, glucose at a concentration range of 1 nM to 200 ??M was detected in the presence of glucose oxidase with a limit of detection of 1 nM.