UV-Laser Interference Lithography for Local Functionalization of Plasmonic Nanostructures with Responsive Hydrogel

Area of Science:

• Nanotechnology
• Materials Science
• Biomedical Engineering

Background:

• Plasmonic hotspots on gold nanoparticles are crucial for sensitive biosensing.
• Local functionalization of these hotspots with biomolecules remains challenging.
• Responsive hydrogels offer tunable binding matrices for biosensor applications.

Purpose of the Study:

• To develop a novel method for local functionalization of plasmonic hotspots on gold nanoparticles.
• To create a hybrid material combining gold nanoparticles and a responsive hydrogel matrix for biosensing.
• To demonstrate enhanced fluorescence readout in an immunoassay using this hybrid material.

Main Methods:

• Utilized UV-laser interference lithography to create periodic arrays of thermoresponsive poly(N-isopropylacrylamide)-based (pNIPAAm) hydrogel features.
• Incorporated photocrosslinkable benzophenone groups and carboxylic groups into the hydrogel for attachment and postmodification.
• Overlaid and attached the hydrogel arrays onto periodic arrays of gold nanoparticles to form a 3D binding matrix.
• Postmodified the hybrid material with ligand biomolecules for immunoassay applications.

Main Results:

• Successfully fabricated periodic hydrogel arrays as small as 170 nm using UV interference lithography.
• Created a hybrid material with gold nanoparticles (130 nm diameter) and a pNIPAAm-based hydrogel matrix.
• Demonstrated plasmon-enhanced fluorescence readout of an immunoassay.
• Showcased signal enhancement through hydrogel matrix collapse, compacting the target analyte at the plasmonic hotspot.

Conclusions:

• The reported approach enables precise, local functionalization of plasmonic hotspots.
• The developed hybrid material serves as an effective 3D binding matrix for plasmonic biosensors.
• The thermoresponsive nature of the hydrogel allows for signal amplification in fluorescence-based immunoassays.