Tuning interior nanogaps of double-shelled Au/Ag nanoboxes for surface-enhanced Raman scattering.

Weiqing Zhang,Minghui Hong,Wenxin Niu,Mohsen Rahmani,Serge Ravaine,Xianmao Lu

doi:10.1038/srep08382

Abstract

Double-shelled Au/Ag hollow nanoboxes with precisely controlled interior nanogaps (1 to 16 nm) were synthesized for gap-tunable surface-enhanced Raman scattering (SERS). The double-shelled nanoboxes were prepared via a two-step galvanic replacement reaction approach using Ag nanocubes as the templates, while 4-aminothiolphenol (4-ATP) as SERS probe molecules were loaded between the two shells. More than 10-fold enhancement of SERS is observed from the double-shelled nanoboxes than Ag nanocubes. In addition, the SERS of the double-shelled nanoboxes increase significantly with the decrease of gap size, consistent with the theoretical prediction that smaller gap size induces larger localized electromagnetic enhancement.

Highlights

Double-shelled Au/Ag hollow nanoboxes with precisely controlled interior nanogaps (1 to 16 nm) were synthesized for gap-tunable surface-enhanced Raman scattering (SERS)
The double-shelled nanoboxes were prepared via a two-step galvanic replacement reaction approach using Ag nanocubes as the templates, while 4-aminothiolphenol (4-ATP) as SERS probe molecules were loaded between the two shells
After the coating of Ag, the 4-ATP molecules adsorbed on the surface of each Au/Ag nanobox were buried underneath the Ag shell

Summary

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Double-shelled Au/Ag hollow nanoboxes with precisely controlled interior nanogaps (1 to 16 nm) were synthesized for gap-tunable surface-enhanced Raman scattering (SERS). Lim et al synthesized Au nano-bridged core-shell particles with a 1-nm interior gap loaded with Raman dyes In their method, DNA-modified Au nanoparticles were employed as the seeds for the growth of a shell on the surface of the nanoparticles. By controlling the thickness of the Ag coated on the single-shelled nanoboxes as well as the amount of HAuCl4 solution added in the second GRR, the size of the nanogap could be precisely tuned from 1 to 16 nm This structure offers an ideal platform for the study of gap size effect on the SERS signals for molecules sandwiched between two metallic shells. Since no polymer or DNA molecules are used to control the gap size, the SERS measurement is free of interference

Results and Discussion

Methods

Additional information