Improving the selective naked-eye detection of COVID-19 mediated by simultaneously using three different target oligonucleotides coated on plasmonic AuNPs/hexagonal Ag@AuNPs

Abstract

The localized surface plasmon resonance (LSPR) phenomenon provides a versatile property in biosensor technology. This uncommon feature was utilized to produce a homogeneous optical biosensor to detect COVID-19 by the naked-eye readout. In this work, we synthesized two types of plasmonic nanoparticles: (i) AuNPs and (ii) hexagonal core-shell nanoparticles-Au shell on AgNPs (Au@AgNPs). We report herein the development of two colorimetric biosensors employing the efficient targeting and the binding ability for three regions of the COVID-19 genome, that is, S-gene, N-gene and E-gene, at the same time. Two AuNPs and Ag@AuNPs individually coated with three different targets oligonucleotide sequence (TOs) (AuNPs-TOs-mix and Ag@AuNPs-TOs-mix) for simultaneous detection of S-gene, N-gene and E-gene of the COVID-19 virus, using the LSPR and naked-eye methods in the laboratory and biological samples. The target COVID-19 genome RNA detected using the AuNPs-TOs-mix and Ag@AuNPs-TOs-mix can achieve the same sensitivity. The detection ranges by the AuNPs-TOs-mix and Ag@AuNPs-TOs-mix are both sufficiently improved in equal amounts in comparison to any of the AuNPs-TOs and Ag@AuNPs-TOs. The sensitivity of the current COVID-19 biosensors were 94% and 96% based on the number of positive samples detected for AuNPs-TOs-mix and Ag@AuNPs-TOs-mix, respectively. Moreover, all the real-time PCR confirmed negative samples obtained the same results by the biosensor; accordingly, the specificity of this approach got to 100%. The current study reports a selective, reliable, reproducible and visual ‘naked-eye’ detection of COVID-19, devoid of the requirement of any sophisticated instrumental techniques.

Communicated by Ramaswamy H. Sarma

Keywords:

• AuNPs
• Ag@AuNPs
• naked-eye detection
• COVID-19
• target oligonucleotide
• LSPR

Acknowledgements

Not applicable.

Author contributions

All authors contributed to the study conception and design. R.N. and N.H.M. are responsible for the conception and design of the work. N.H.M., A.G., A.J. and A.S.D. conducted the literature search, data analysis, and drafted the article. All authors reviewed this draft, contributed and approved the final manuscript.

Ethics approval and consent to participate

The ethics committee of Hamadan University of Medical Sciences approved all the experimental steps (IR.UMSHA.REC.1399.512).

Consent for publication

All the authors approved the version to be published and agreed to be accountable for all aspects of the work.

Disclosure statement

The authors declare that they have no competing interests.

Data availability statement

All data generated or analyzed during this study are included in this published article.

Additional information

Funding

This study was funded by Hamadan University of Medical Sciences under Grant number 9907295321.