Plasmonic Fiberoptic Absorbance Biosensor (P-FAB) for Rapid Detection of SARS-CoV-2 Nucleocapsid Protein

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Infectious Disease Diagnostics

Background:

• Current COVID-19 diagnostic methods like RT-PCR are expensive and time-consuming.
• SARS-CoV-2 nucleocapsid protein is an abundant biomarker for infection.
• There is a need for rapid, point-of-care diagnostic tools.

Purpose of the Study:

• To develop a rapid, wash-free plasmonic fiber optic absorbance biosensor (P-FAB) for SARS-CoV-2 N-protein detection.
• To optimize sensor components, including optical fiber material and gold nanoparticle (AuNP) label size.
• To establish a sensitive and efficient point-of-care diagnostic strategy.

Main Methods:

• A sandwich assay was designed using a U-bent fiber optic sensor probe and AuNP labels.
• Evanescent wave absorbance (EWA) sensitivity was utilized for detection.
• Optical fiber materials (silica vs. polymeric) and AuNP sizes (20, 40, 60 nm) were evaluated.

Main Results:

• The P-FAB strategy demonstrated high sensitivity and a low limit of detection (LoD).
• Fused silica/glass optical fiber (GOF) and ~40 nm AuNP labels yielded an LoD of ~2.5 ng/mL.
• Detection was achieved within a rapid 10-minute read-out time.

Conclusions:

• The developed P-FAB is a promising technology for rapid, point-of-care COVID-19 diagnosis.
• This biosensor offers a sensitive and efficient alternative to conventional diagnostic methods.
• Further development for a point-of-care device and preclinical studies are underway.