Petal-like gap-enhanced Raman tags with a controllable structure

Abstract

Surface-enhanced Raman scattering tags show promising potential for in vitro and in vivo bioimaging applications due to lack of photobleaching and narrow spectral lines. However, reproducible and controllable growth of nanostructures with a high density of hot-spots is still a challenge. In this work we report on an improved strategy for the synthesis of core/shell Raman tags with a high density of hot-spots from petal-like shell structures and a high-rate immobilization of reporter molecules. The strategy based on simultaneous growth and reporter functionalization of the Au shell around Au nanospheres coated with 4-nitrobenzenethiol. We obtained that the amount of added 4-nitrobenzenethiol controls the structure of the resulted particles. Various types of particles were obtained including gap-enhanced Raman tags (GERTs) with a solid shell, petal-like GERTs, porous Au particles filled with Raman molecules. Optimized petal-like tags (p- GERTs) demonstrate a SERS response 50 times higher than usual gap-enhanced Raman tags, which make them suitable for spectroscopy at the single-particle level. Due to the high SERS response and unique porous structure these nanoparticles have great potential for biomaging and other applications.