Optically Trapped Surface-Enhanced Raman Probes Prepared by Silver Photoreduction to 3D Microstructures

Area of Science:

• Nanotechnology
• Spectroscopy
• Optics

Background:

• Surface-enhanced Raman spectroscopy (SERS) requires specialized substrates for enhanced sensitivity.
• Optical tweezers offer precise manipulation of microscale objects.
• Combining these techniques can enable advanced molecular analysis.

Purpose of the Study:

• To develop and test 3D microstructures functionalized with silver nanoparticles for SERS applications.
• To integrate these microstructures with optical tweezers for controlled manipulation and analysis.
• To investigate the effect of silver layer characteristics on SERS performance.

Main Methods:

• Fabrication of 3D microstructures using two-photon polymerization of SU-8 photoresist.
• Manipulation of microstructures within a dual-beam optical trap.
• Coating microstructures with a SERS-active silver layer via chemically assisted photoreduction.
• Characterization of silver layer morphology using scanning electron microscopy.
• Testing SERS performance with emodin and hypericin molecules.

Main Results:

• Successfully developed 3D microstructures with controllable silver nanoparticle coverage.
• Demonstrated precise manipulation of these microstructures using optical tweezers.
• Observed variations in SERS spectra based on silver layer characteristics.
• Successfully measured SERS spectra of emodin and hypericin using the developed system.

Conclusions:

• The developed 3D microstructures functionalized with silver nanoparticles are effective SERS substrates.
• The integration with optical tweezers allows for targeted molecular analysis.
• This approach offers a promising platform for sensitive and spatially resolved spectroscopic investigations.