Petal-like Gap-Enhanced Raman Tags with Controllable Structures for High-Speed Raman Imaging

Area of Science:

• Nanotechnology
• Spectroscopy
• Bioimaging

Background:

• Surface-enhanced Raman scattering (SERS) is crucial for in vitro and in vivo bioimaging.
• Fabricating SERS tags with controllable hot-spots and high reporter molecule density remains a challenge.

Purpose of the Study:

• To develop an improved strategy for synthesizing core/shell Raman tags with enhanced SERS properties.
• To investigate the role of 4-nitrobenzenethiol (NBT) in controlling the structure and SERS response of nanoparticles.

Main Methods:

• Simultaneous growth and functionalization of an Au shell around Au nanospheres coated with 4-nitrobenzenethiol (NBT).
• Controlled addition of NBT to influence particle morphology (sGERTs, pGERTs, mGERTs).
• Comparative analysis of SERS response using different thiol molecules (NBT, BDT, NT).

Main Results:

• Demonstrated formation of smooth solid (sGERTs), petal-like (pGERTs), and mesoporous (mGERTs) gap-enhanced Raman tags (GERTs).
• NBT uniquely facilitates the formation of pGERTs and mGERTs, unlike BDT and NT.
• Optimized pGERTs exhibit a 50-fold higher SERS response compared to sGERTs.
• Successful high-speed cell imaging achieved with pGERTs in approximately 1 minute.

Conclusions:

• The proposed growth mechanism explains NBT's role in forming unique GERT structures.
• pGERTs offer superior SERS performance, suitable for single-particle spectroscopy.
• These novel nanoparticles hold significant potential for advanced bioimaging and other applications due to their high SERS activity and porous structure.