A Rapid SARS-CoV-2 Nucleocapsid Protein Profiling Assay with High Sensitivity Comparable to Nucleic Acid Detection

Area of Science:

• Biotechnology
• Nanotechnology
• Molecular Diagnostics

Background:

• Current COVID-19 diagnostic methods struggle to balance sensitivity and speed.
• Effective epidemic control requires simple, fast, and sensitive screening tools.

Purpose of the Study:

• To develop a rapid, ultrasensitive, and highly specific assay for COVID-19 antigen profiling.
• To enable quantitative detection of SARS-CoV-2 nucleocapsid (N) protein in saliva.

Main Methods:

• Utilized a nanoparticle scaffold with aptamer binding for DNA assembly and fluorescence translation.
• Developed a binding-induced DNA assembly mechanism triggered by target antigen binding.
• Employed metal-enhanced fluorescence for signal amplification.

Main Results:

• Achieved quantitative profiling of saliva N protein into fluorescence signals within 3 minutes.
• Demonstrated a limit of detection as low as 150 fg mL⁻¹, surpassing ELISA kits and rivaling PCR.
• Exhibited high recognition ratio and specificity for the target antigen.

Conclusions:

• The developed assay is rapid, ultrasensitive, specific, and easy to operate.
• This method shows significant potential for widespread screening of COVID-19 and emerging epidemics like monkeypox.
• Offers a viable alternative to existing diagnostic methods for public health surveillance.