Single-Molecule Evaluation of the SARS-CoV-2 Nucleocapsid Protein Using Gold Particle-in-a-Frame Nanostructures...

Area of Science:

• Nanotechnology
• Biotechnology
• Analytical Chemistry

Background:

• Detecting low-abundance analytes like SARS-CoV-2 antigen is crucial for disease profiling.
• Existing assays face challenges in achieving single-molecule sensitivity for viral antigens.

Purpose of the Study:

• To develop an ultrasensitive assay for direct SARS-CoV-2 antigen detection.
• To utilize gold particle-in-a-frame nanostructures (Au PIAFs) for enhanced fluorescence detection.

Main Methods:

• An aptamer claw strategy was employed for SARS-CoV-2 antigen evaluation.
• Gold particle-in-a-frame nanostructures (Au PIAFs) served as metal-enhanced fluorescence materials.
• The assay was integrated with a microplate reader for rapid detection.

Main Results:

• Achieved a sensitivity of 44 fg·mL⁻¹ in under 3 minutes.
• Accurately detected SARS-CoV-2 nucleocapsid protein (N protein) in human saliva.
• Demonstrated a limit of detection as low as 0.84 ag·mL⁻¹ with a single-molecule counting platform.

Conclusions:

• The developed aptamer claw assay offers rapid and ultrasensitive SARS-CoV-2 antigen detection.
• This assay holds significant potential for screening SARS-CoV-2 and other contagious viruses.
• The Au PIAF nanostructures provide a powerful platform for sensitive bioanalytical applications.