Ultrabright gap-enhanced Raman tags for high-speed bioimaging

Area of Science:

• Nanotechnology
• Spectroscopy
• Bioimaging

Background:

• Surface-enhanced Raman spectroscopy (SERS) offers advantages over fluorescence for bioimaging, including narrow spectral linewidth and reduced photobleaching.
• Current SERS imaging speed is limited by the weak Raman signals from conventional SERS nanoprobes, hindering practical applications.

Purpose of the Study:

• To develop novel, ultrabright SERS nanoprobes to enhance imaging speed and sensitivity.
• To address the limitations of existing SERS nanoprobes for efficient bioimaging.

Main Methods:

• Fabrication of gap-enhanced Raman tags (GERTs) utilizing interior sub-nanometer gaps and external petal-like shells.
• Engineering GERTs to maximize electromagnetic hot spots, immobilization surface area, and reporter molecule Raman cross-section.
• Utilizing a low-power laser (370 μW) for SERS imaging.

Main Results:

• Achieved a Raman enhancement factor exceeding 5 × 10^9.
• Demonstrated detection sensitivity at the single-nanoparticle level.
• Realized high-resolution cell imaging in 6 seconds and wide-area sentinel lymph node imaging (3.2 × 2.8 cm^2) in 52 seconds with high contrast (SBR=80).

Conclusions:

• The developed GERTs significantly enhance SERS performance, offering a potential solution to the speed and sensitivity bottlenecks in SERS-based bioimaging.
• These ultrabright nanoprobes pave the way for faster and more sensitive in vivo imaging applications.