Inactivated Influenza A H1N1 (Michigan/45/15)

Here, researchers developed and characterized a MXene-graphene field-effect transistor (FET) sensor for influenza virus and 2019-nCoV sensing. The developed sensor was tested with different concentrations of antigens of two viruses: inactivated influenza A (H1N1) HA virus, ranging from 125 to 250,000 copies/mL, and recombinant 2019-nCoV spike protein, ranging from 1 fg/mL to 10 pg/mL. The average response time was about ∼50 ms, significantly faster than the existing real-time reverse transcription polymerase chain reaction method (> 3 hours). The low detection limit demonstrated the sensitivity of the MXene-graphene ultra-sensitive virus-sensing transduction material (VSTM) on the FET platform for virus sensing. In particular, the high signal-to-virus loading ratio (~10% change in source-drain current and gate voltage) also demonstrated the ultrasensitivity of the developed MXene-graphene FET sensor. Furthermore, the specificity of the sensor was demonstrated by depositing inactivated influenza A (H1N1) HA virus and recombinant SARS-CoV-2 spike protein into microfluidic channels with opposite antibodies, which reduced the signal difference by about 10 times. Therefore, the researchers successfully constructed a relatively low-cost, extremely sensitive, fast-response, and highly specific inactivated influenza A (H1N1) and SARS-CoV-2 sensor using MXene-graphene VSTM.

Here, the researchers investigated the specific binding of inactivated influenza A (H1N1) virus to influenza A (H1N1) HA polyclonal antibodies and the specific binding of recombinant 2019-nCoV spike protein to SARS-CoV-2 spike protein to explore the specificity of the sensor (Figure 1A). Influenza A (H1N1) HA polyclonal antibodies were functionalized onto field effect transistor (FET) sensors and recombinant 2019-nCoV spike protein samples were added. When PBS buffer was used as the electrolyte, the field effect transistor (FET) sensor with immobilized influenza A (H1N1) HA polyclonal antibodies showed very little response to recombinant 2019-nCoV spike protein, even at the highest concentration (10 pg/mL) tested in previous experiments (Figure 1B, D). Similarly, the FET sensor functionalized with SARS-CoV-2 spike antibody showed very small response to inactivated influenza A (H1N1) virus (250,000 copies/mL) (Figure 1C, D). Similar results were obtained using artificial saliva as the electrolyte. Smaller responses were observed when unpaired antibodies and viruses were used.

Figure 1. (A) Depiction of specific binding studies within PBS samples. (B) IDS-VG curves of influenza A virus (H1N1) HA polyclonal antibody immobilized FET sensor and (C) SARS-CoV-2 spike antibody immobilized FET sensor. (D) Normalized gate-voltage shift and drain-source current changes with STDs in the specific binding study. (Li Y, et al., 2021)