Amplification Free Detection of SARS-CoV-2 Using Multi-Valent Binding.

Area of Science:

• Biosensor development
• Nucleic acid detection
• Electrochemical methods

Background:

• Sensitive detection of SARS-CoV-2 RNA is crucial for COVID-19 diagnostics.
• Electrochemical impedance spectroscopy (EIS) offers label-free nucleic acid detection.
• Multi-valent binding strategies can enhance biosensor sensitivity by increasing binding events.

Purpose of the Study:

• To develop and optimize EIS-based biosensors for sensitive SARS-CoV-2 RNA detection.
• To investigate the efficacy of multi-valent binding strategies for improving biosensor performance.
• To evaluate the biosensor's performance in detecting SARS-CoV-2 RNA in patient samples.

Main Methods:

• Development of EIS biosensors utilizing multi-valent binding strategies.
• Exploration of two probe-design approaches: single-valent probe combinations and intrinsic multi-valent probes.
• Theoretical modeling to explain observed signal suppression due to inter- and intra-probe hybridization.
• Validation of biosensor performance using clinical patient samples.

Main Results:

• Multi-valent binding approaches significantly enhanced SARS-CoV-2 RNA detection sensitivity.
• A probe combination strategy achieved a limit of detection (LOD) of 182 copies/μL.
• Signal suppression was observed and theoretically explained by probe hybridization interactions.
• Successful evaluation of patient samples for COVID-19 diagnostics was demonstrated.

Conclusions:

• Multi-valent binding is a highly effective strategy for enhancing EIS biosensor sensitivity for nucleic acid targets.
• The developed biosensor shows promise for direct, label-free detection of SARS-CoV-2 RNA.
• This technology has significant potential for point-of-care diagnostics and infectious disease monitoring.