Amplification Free Detection of SARS-CoV-2 Using Multi-valent Binding

Appan Roychoudhury, R. J. Allen, Tine Curk, James D Farrell, Gina E. M. McAllister, Kate Templeton, Till T Bachmann

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We present the development of electrochemical impedance spectroscopy (EIS)-based biosensors for sensitive detection of SARS-CoV-2 RNA using multi-valent binding. By increasing the number of probe–target binding events per target molecule, multi-valent binding is a viable strategy for improving the biosensor performance. As EIS can provide sensitive and label-free measurements of nucleic acid targets during probe–target hybridization, we used multi-valent binding to build EIS biosensors for targeting SARS-CoV-2 RNA. For developing the biosensor, we explored two different approaches including probe combinations that individually bind in a single-valent fashion and the probes that bind in a multi-valent manner on their own. While we found excellent biosensor performance using probe combinations, we also discovered unexpected signal suppression. We explained the signal suppression theoretically using inter- and intra-probe hybridizations which confirmed our experimental findings. With our best probe combination, we achieved a LOD of 182 copies/μL (303 aM) of SARS-CoV-2 RNA and used these for successful evaluation of patient samples for COVID-19 diagnostics. We were also able to show the concept of multi-valent binding with shorter probes in the second approach. Here, a 13-nt-long probe has shown the best performance during SARS-CoV-2 RNA binding. Therefore, multi-valent binding approaches using EIS have high utility for direct detection of nucleic acid targets and for point-of-care diagnostics.
Original languageEnglish
Pages (from-to)3692-3699
JournalACS Sensors
Issue number12
Early online date8 Dec 2022
Publication statusPublished - 23 Dec 2022

Keywords / Materials (for Non-textual outputs)

  • COVID-19/diagnosis
  • Humans
  • Nucleic Acid Hybridization
  • RNA, Viral/genetics
  • SARS-CoV-2/genetics


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