Controlled synthesis of high yield polyhedral polyethylenimine-capped gold nanoparticles for real-time reaction monitoring by SERS

Abstract

Polyethylenimine (PEI)-capped gold nanoparticles have found a wide use in the sensing, catalytic, and biomedical fields. However, a controlled synthesis of well-defined polyhedral PEI-capped gold nanoparticles is yet to be explored. In this work, we have demonstrated that, through a seeded growth, well-defined polyhedral PEI-capped nanoparticles of gold (38–50 nm) can be synthesized. The numerous sharp tips and edges facilitated their use as both active surface-enhanced Raman scattering (SERS) and catalytic materials. Using the conversion of 4-nitrothiophenol to 4-aminothiophenol as a model reaction, the SERS and catalytic properties of the polyhedral PEI-capped nanoparticles were simultaneously demonstrated. The polyhedral gold nanoparticles, thus, serve as a simple but active bifunctional substrate for in situ SERS-based chemical reaction monitoring. In addition, the easy fabrication of these bifunctional nanoparticles makes them stand out from the numerous conventional substrates that require a multistep and complex process of integrating catalytic and SERS properties into a single nanomaterial.