4th Commonwealth Chemistry Posters

A Localized Surface Plasmon Resonance Aptasensor for Rapid and Selective Detection of the SARS-CoV-2 Antigens

Tyra Lewis, Erin Giroux, Dr. Sanela Martic,

Department of Environmental and Life Sciences, Forensic Science, Trent University, Peterborough, ON Canada

Conventional Testing

Conventional methods for viral detection, such as polymerase chain reaction (PCR), can be costly, time-consuming, and accompanied by high false -negative and -positive rates.¹

Viral Target

Approaches that target viral proteins, such as the Spike (S) protein can lead to higher sensitivity and offers the potential for early diagnostic testing of viral infection.²

•The high demand on testing of suspected COVID-19 cases has demonstrated the need for efficient, accurate, rapid and reliable solutions for viral detection.

•The SARS-CoV-2 spike antigen plays a vital role in the function of the coronavirus and can be used as a diagnostic biomarker for viral infections.

•For sensing applications, aptamers are suitable, high-affinity and cost-effective binding partners to their targets, including viral antigens.^1,2

The binding interaction between single stranded DNA (ssDNA) aptamers and the SARS-CoV-2 S1 protein was evaluated using localized surface plasmon resonance (LSPR).³

DEVELOPEMENT OF THE LSPR APTASENSOR

Localized Surface Plasmon Resonance (LSPR) Measurement:

All LSPR measurements were performed using a 2-channel OpenSPR (NicoyaLifeSciences) and data analyzed using TraceDrawer Software to determine the association rate (k_a), dissociation rate (k_d), and dissociation constant (K_D).³

EVALUATION OF ANTIGEN-APTAMER INTERACTIONS

Aptamer Design

LSPR sensorgram representing the fabrication of the S1 aptasensor including: (1) attachment of streptavidin to the biotin-AuNP surface, (2) immobilization of the biotinylated S1 aptamer, (3) 10-min S1 antigen association, and (4) surface regeneration allowing for subsequent measurement of another sample.

S1 Aptamer Selectivity Amongst SARS-CoV-2 Antigens

S1 aptamer-antigen complex had the best performance K_D = 0.41 +/- 0.23 nM. LSPR signal recognition of SARS-CoV-2 S1, RBD and S2 antigens or BSA to the S1- aptasensor. The S1 aptasensor showed selective to the SARS-CoV-2 S1 antigen. [Antigens] = 2.5 μg/mL.

Kinetic Evalutation of the Antigen-Aptamer Interaction

Kinetic evaluation suggests a strong binding interaction between the SARS-CoV-2 S1 protein and the S1 aptamer and high affinity toward the SARS-CoV-2 S1 protein (K_D = 0.41 ± 0.23 nM).

CONCLUSIONS

Direct and selective detection of the SARS-CoV-2 S1 protein was achieved using the S1 aptamer with LSPR.

Using LSPR, the binding of the S1 protein to the immobilized aptamer was monitored in real-time.

Surface regeneration allows for reuse of the aptasensor for multiple measurements.

OpenSPR can be used to monitor aptamer-protein interactions for application to coronavirus related measurements.

Using the streptavidin-biotin chemistry, a limit of detection of 0.26 nM and limit of quantification of 1.05 nM was achieved.

The LSPR aptasensor is a promising platform for assessing viral protein interactions in complex solutions, such as those that mimic biological fluids.

FUTUTRE WORK

LSPR evaluation of sensor performance using clinical samples to further investigate efficiency of the aptasensor in real-life applications

Comparison of SARS-CoV-2 sensors using other sensor chemistries such as carboxyl-amine and gold-thiol.

Utilize LSPR to determine the ability of DNA aptamers to serve as interferents of the ACE2-RBD binding interactions; toward the development of anti-viral therapies

REFERENCES

1)Chen, Z., et al., Virol. Sin. 2020, 35 (3), 351–354. https://doi.org/10.1007/s12250-020-00236-z.

2)Song, Y., et al., Anal. Chem. 2020, 92 (14), 9895–9900. https://doi.org/10.1021/acs.analchem.0c01394.

3)Lewis T., Giroux E., Jovic M., Martic S. Analyst, 2021, 146:7207-7217. doi: 10.1039/d1an01458g.

ACKNOWLEDGEMENTS

The authors would like to thank Trent University and the Martic Lab group for their support, as well as Nicoya LifeSciences for their contributions. This work is funded by NSERC Alliance COVID-19.

4th Commonwealth Chemistry Posters

A Localized Surface Plasmon Resonance Aptasensor for Rapid and Selective Detection of the SARS-CoV-2 Antigens

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