Titanium-vanadium oxide nanocomposite based solid-state dual-electrode sensor for SARS-CoV-2 nucleic acid detection

11 February 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


COVID-19 outbreak, caused by the SARS-CoV-2 RNA virus, elevates the need for a rapid, reliable, inexpensive, and easily accessible disease diagnostic tool. The present go-to approach for SARS-CoV-2 RNA detection is the real-time reverse transcriptase polymerase chain reaction (RT-PCR) test which despite being the most reliable method has few drawbacks including being lengthy and laborious. Approaching the diagnosis from an electrochemistry pathway is a relatively economical, decentralized and yet highly sensitive route. This work aims to construct an electrochemical (bio)sensor with 2-electrode geometry with a transition metal oxide (TMO) based sensing layer. We have fabricated a series of TiO2-V2O5 (TVO) nanocomposites to probe their electrochemical performance and attain a highly sensitive dual-electrode electrochemical sensor (DEES) compared to the pristine V2O5. The XRD analysis of the electrodes confirmed the formation of nanocomposite while the XPS analysis correlated the formation of oxygen vacancies with improved electrical conduction measured via EIS and I-V characterization. The optimized electrode was then utilized to electrochemically detect end-point LAMP readout for 10^1 – 10^4 copies of plasmid DNA and in vitro transcribed SARS-CoV-2 RdRp RNA in an aqueous solution. Additionally, the DEES was also applied to detect in situ LAMP performed on SARS-CoV-2 plasmid and RNA magneto-extracted from a) aqueous solution; b) sample spiked with excess human genomic DNA, and c) a viral transport medium (VTM)-mimic sample. The DEES results were compared with real-time fluorescence and commercially available screen-printed electrodes (SPE). Our device was able to successfully detect magneto-extracted plasmid DNA and in vitro transcribed SARS-CoV-2 RNA to the limit of detection of 2.5 copies/μL.


Electrochemical biosensor

Supplementary materials

Supplementary Information for "Titanium-vanadium oxide nanocomposite based solid-state dual-electrode sensor for SARS-CoV-2 nucleic acid detection"
Supporting information contains crystallite size and film thickness values, signal %-change for electrochemical detection, electroanalytical data of 100𝜇M MB for FTO alone and 20%-TVO deposited FTO, redox pair for the electrochemical probe methylene blue (MB), additional X-ray diffraction patterns, X-ray photoelectron spectroscopy analysis, and FE-SEM micrographs. Measured thickness profiles, Bode plot, chronoamperometry measurements, I-V characteristics of 20%-TVO collected for 100𝜇M MB and buffer alone, current signal comparison of 20%-TVO electrode and MnO2 electrode, and chronoamperometry of NTC and plasmid DNA LAMP.


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