High sensitivity molecule detection by plasmonic nanoantennas with selective binding at electromagnetic hotspots

Area of Science:

• Nanotechnology
• Biomolecular Detection
• Plasmonics

Background:

• Plasmonic nanoantennas offer unique optical properties for sensing applications.
• Achieving high sensitivity in biomolecule detection remains a key challenge.
• Controlling molecular binding sites is crucial for signal enhancement.

Purpose of the Study:

• To develop a highly sensitive biomolecule detection platform using plasmonic nanoantenna arrays.
• To investigate the effect of selective binding at optical hotspots on detection sensitivity.
• To explore the potential for single-molecule detection using this nanoantenna system.

Main Methods:

• Fabrication of plasmonic nanoantennas comprising separated gold nanorods with a titanium disk.
• Application of selective surface modification chemistry for controlled binding within nanoantenna gaps.
• Optical characterization using dark-field microscopy.
• Finite-difference time-domain (FDTD) simulations to analyze optical responses.

Main Results:

• Selective binding in the nanoantenna gaps ensures high detection sensitivity.
• Optical signals increase with decreasing gap size after streptavidin binding.
• The signal per bound molecule in nanoantennas is six times higher than with single nanorods.

Conclusions:

• Plasmonic nanoantenna arrays with selective binding at optical hotspots enable highly sensitive biomolecule detection.
• The demonstrated signal enhancement is promising for future single-molecule detection applications.
• Optimizing gap size is critical for maximizing detection sensitivity in plasmonic sensing.