Label-free biosensing with singular-phase-enhanced lateral position shift based on atomically thin plasmonic...

Area of Science:

• Plasmonics and Nanotechnology
• Biosensing and Diagnostics
• Materials Science

Background:

• Conventional plasmonic sensors require secondary labels for higher sensitivity, limiting their application in early disease diagnosis.
• Angle-interrogating plasmonic sensors face challenges in achieving high sensitivity without amplification strategies.

Purpose of the Study:

• To develop a highly sensitive plasmonic biosensor by enhancing the lateral position shift using phase singularity.
• To utilize a novel germanium-antimony-tellurium (GST) layer as a phase-response-enhancing material for plasmonic sensing.

Main Methods:

• Fabrication of an atomically thin germanium-antimony-tellurium (GST) layer on a silver nanofilm.
• Engineering the GST layer to induce phase singularity and enhance the lateral position shift of the reflected beam.
• Utilizing the enhanced lateral position shift for label-free detection of biomolecules.

Main Results:

• Achieved a record-breaking lateral position shift of 439.3 μm, demonstrating an ultra-high sensitivity of 1.72 × 10⁸ nm RIU^-1.
• Determined a low detection limit of 6.97 × 10^-7 RIU with a figure of merit (FOM) of 4.54 × 10¹¹ μm (RIU∙°)^-1.
• Successfully detected trace amounts of cytokine biomarkers (TNF-α, IL-6) down to 1 × 10^-16 M and measured protein-ligand interactions.

Conclusions:

• The developed plasmonic biosensor with GST exhibits unprecedented sensitivity and a large FOM for label-free detection.
• This technology enables the detection of critical cancer biomarkers at clinically relevant low concentrations.
• The sensor demonstrates potential for advancing early disease diagnosis and molecular biology research.