Biosensors for detection of SARS-CoV-2 infection

Vaishnavi Kardale, Bioinformatics Centre, Savitribai Phule Pune University

Many biochemical processes have been described for the detection of antigens. These processes have high specificity, have high reproducibility, and are trustworthy. Several new biochemical processes are being developed with even better sensitivity. However, the downside of biochemical processes is that they are slow and require specialized training. As opposed to this, biosensors provide a much faster response (on the timescale of a few seconds) and do not usually require special training. Many analytical processes, such as the multiple rinsing in the case of ELISA, can be avoided to save time.

What are biosensors?

A biosensor is a device that can detect the presence and concentration of a biological analyte like biomacromolecules (carbohydrates, proteins, or nucleic acids). Its use is not just limited to biomacromolecules, as it can also be used to detect the presence of microorganisms. Detection of pathogens (viral, bacterial, fungal, and protozoan) is facilitated by the presence of proteins on the surface of these microorganisms. This highlights the importance of biosensors in disease diagnosis. A biosensor mainly consists of three parts – there is a part to recognize and produce a signal, a signal transducer to amplify the signal, and a reader device to read the signal.

Biosensors have proved to be valuable because they can be used for both qualitative and quantitative analysis. When electronic biosensors come in contact with a biological entity then cause a change in the dipole moment. These changes, occurring due to analyte binding, can then be amplified via a field- electric transistor (FET).

How can Biosensors be used?

Graphene electrodes coated with the specific antibody for the spike protein of SARS-CoV-2 combined with FET-based biosensors can be used for the detection of the SARS-CoV-2 virus that has caused the COVID19 pandemic. Despite this advancement, the use of biosensors for the detection of COVID19 has been sparse. This is due to the complex device design, fabrication difficulties, and substandard performance with regard to selectivity, sensitivity, and stability.

New research suggests the use of organic electrochemical transistors (OECT) combined with antigen- specific nanobodies can detect the spike protein from SARS-CoV-2 and MERS-CoV from saliva or serum in under 10 minutes. This combined with the fact that the detection is at a single-molecular level has raised the hopes of researchers. OECT has proved to be useful in many biological systems.

What is a nanobody?

A typical FET uses a complete antibody (2 heavy and 2 light chains) for the detection of the biological analyte. In this study, rather than using a full antibody, the researchers employed camelid- derived nanobodies. A camelid-derived antibody is derived from the Camelidae family of mammals and has only the heavy chain component of the antibody.

What next?

The results of this study and its use in the detection of COVID-19 with high sensitivity at the nanomolar level in the saliva are particularly promising. The COVID-19 pandemic has added to the emergency of developing faster, inexpensive, and easy to operate assays to determine the viral load. Methods requiring less technical skills would help to carry out tests at large. This has stressed the urgency to develop electronic biosensors as its benefit over traditional assays is evident.

Also read: Brain networks control neural activity and communication

Reference:

1. Katz, H.E. Antigen sensing via nanobody-coated transistors. Nat Biomed Eng 5, 639–640. (2021). https://doi.org/10.1038/s41551-021-00765-2

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Author info:

Vaishnavi Kardale is a master’s student at the Bioinformatics Centre, Savitribai Phule University. She is interested in protein folding mechanisms and wants to study them further.

Some of her previous publications are:

1. https://bioxone.in/news/worldnews/the-gene-responsible-for-eye-lens-formation-revealed/
2. https://bioxone.in/news/worldnews/comeback-of-tuberculosis-but-its-drug-resistant-now/
3. https://bioxone.in/news/worldnews/a-drug-to-reduce-covid-infection-by-99/
4. https://bioxone.in/news/worldnews/artificial-intelligence-ai-for-efficient-covid-testing/
5. https://bioxone.in/news/worldnews/deephbv-a-machine-learning-tool-to-aid-in-hepatitis-b-integration-site-detection/