Enhanced Refractive Index Sensitivity of Linearly Assembled Gold Nanoantennae for Biosensing Applications

Area of Science:

• Plasmonics and Nanotechnology
• Biosensing and Biofabrication
• Materials Science

Background:

• Supracolloidal structures exhibit unique plasmonic properties, superior to individual nanoparticles, for sensing local refractive index changes.
• Linear periodic assemblies of gold nanoparticles (AuNPs) offer enhanced plasmonic responses crucial for sensitive detection.
• Developing scalable fabrication methods for these structures is key for practical biosensing applications.

Purpose of the Study:

• To fabricate large-scale (1 cm²) linear periodic assemblies of AuNPs using template-assisted methods.
• To demonstrate the polarization-dependent biosensing performance of these AuNP assemblies.
• To investigate the potential of these platforms for detecting biomarkers such as Tumor Necrosis Factor-Alpha (TNF-α).

Main Methods:

• Template-assisted fabrication of AuNP assemblies using laser interference lithography (LIL) and wrinkle-assisted patterning.
• Characterization of sensor performance using glycerol/water mixtures to assess refractive index sensitivity.
• Biofunctionalization and detection of anti-TNF-α antibodies using polarized-light vis-NIR spectrometry.

Main Results:

• Both LIL and wrinkle-assisted patterning yielded comparable sensing performances, demonstrating broad utility.
• A pronounced polarization-dependent plasmonic resonance peak shift (Δλ) was observed.
• Signal enhancement of up to 5-fold was achieved in the longitudinal mode compared to the transversal mode.

Conclusions:

• Supracolloidal AuNP assemblies provide a highly sensitive platform for plasmonic biosensing.
• The developed fabrication approaches are scalable and cost-effective, enabling potential for mass production.
• The polarization-dependent response offers a unique feature for enhanced biosensing capabilities and biomarker detection.