RAPID: Dual COVID-19 and Influenza Virus Detection via Target Antibody-Functionalized Graphene Field-Effect Sensing

Both COVID-19 and Influenza are infectious respiratory diseases, and their symptoms are hard to distinguish at the early stage. Influenza, commonly known as the flu, spreads through the world in yearly outbreaks, mainly in the fall-winter season, and causes up to 650,000 death per year with 3-5 million severe cases. COVID-19, emerged recently, has already been positively detected in almost 4 million individuals worldwide. Due to the absence of effective, low-cost, point-of-care detection methods, the number of affected individuals is estimated to be, perhaps, 10- fold higher. While scientists, doctors, and whole nations are hard at work to resolve the pandemic, there exists a pressing and urgent need for diagnostics that can differentiate between COVID-19 and influenza. The situation is such that a second wave of the coronavirus spread will likely appear in the fall/winter of 2020, which also coincides with the seasonal outbreak of influenza. Therefore, it is of rapid importance to develop a dual specific and selective biosensor for direct confirmation of the presence of influenza and/or COVID-19 virus within the patient?s body fluids, such as saliva. Authors of the work propose to utilize ultrasensitive graphene nanomaterial transistors, that are functionalized with the antibodies as the virus-specific biosensors. The researchers aim to build a sensor explicitly designed towards the detection of virus bodies directly. Successful completion of this project will lead to an early-stage diagnosis tool that differentiates between influenza and COVID-19, yet embodied into a single device, which is crucial for containing the forthcoming outbreak in order to promote public health.

The investigators intend to approach the problem of virus detection by building a specific dual bioelectronic sensor that employs electrolyte-gated graphene-based field-effect transistors. Among other potential detection methods and transducers, electrolyte-gated graphene field-effect transistors are known for their extremely high sensitivity to analytes. Besides, graphene is biocompatible, stable in ambient, and inert in the aqueous environments. The graphene channel will be functionalized with specific antibodies through a 1-pyrenebutanoic acid, succinimidyl ester (PASE) linker molecule. PASE will facilitate the particular conjugation with both COVID-19 specific, and influenza-specific antibodies. Building upon the direct PASE-antibody conjugation, the researchers plan to explore another, more robust and modular path, which employs conjugation of graphene with ssDNA and use the antibody:compDNA hybrids to improve the antibody attachment onto graphene. The particular conjugation of graphene-to-SARS-CoV-2 and graphene-to-H1N1 specific antibodies will be studied within the scope of the work. In order to test the COVID-19 and Influenza biosensors, the spike protein (S1) and H1 hemagglutinin protein (H1 HA) will be used as analytes, respectively. Based on the protein biosensing, knowledge on the biosensor?s detection limit, their sensitivity, dynamic range, accuracy, and response time will be obtained. Following the dual conjugation of two graphene channels with specific antibodies, one additional channel will be chemically passivated in order to provide a reference signal and allow for the removal of non-specific signals. The inactivated SARS-CoV-2 and H1N1 viruses will then be used to explore the real-world application properties of the built biosensor, exploring specificity and selectivity of such a sensor, cross-reactivity, and throughput. The specific passivation will enable reliable signal recording at the next stage of virus detection, using real body fluid samples to assess the biosensor. Combining a specific and dependable biomolecular integration of both SARS-CoV-2 and H1N1 viruses with graphene?s electrical readout will enable an accurate, specific, and rapid test for the two deadly respiratory diseases.

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