Electronic Spiking Protein-Based COVID Sensors

Abstract

Viruses are ultimate nanotechnology objects with cleverly designed capsid proteins to bind with cell membranes and exquisite DNA/RNA machinery to invade cells and replicate themselves using cells' machinery. Here I will discuss an electronic virus sensor that uses aptamers designed to bind with the COVID-19 spiking proteins S1 and S2 to capture the virus inside a quantum mechanical tunneling gap device. The current through the gap, that is sized to match the COVID-19 diameter of 125 nm, is monitored to detect the presence of the virus. The gap impedance also changes and can be monitored. The sensor works with small amount of saliva deposited over its active area. Saliva is a complex fluid composed of 99.49% water, enzymes, human cells, bacteria, opiorphin, haptocorrin, alfa-amylase, antibacterial compounds, mucus, and electrolytes (sodium, potassium, calcium, etc.). It also contains 60 nm -100 nm exosomes. Except for human cells, bacteria and exosomes, all other fresh saliva components have small molecules (mucus can produce large particles in old saliva). Exosomes and any other nanoparticles inside the fresh saliva can potentially produce false positive results. False negative results, on the other hand, are produced when the viruses in the saliva do not bind with the sensor aptamers. Filtering is used to exclude large (>200 nm) particles. Ultrasonication as well as electric field biasing/excitation techniques are used to ensure virus-aptamer encounter and binding. Exosomes' sizes make them difficult to exclude using filtering. Currently I am developing a technique based on dielectrophoretic responses of exosomes and viruses to preferentially trap the COVID-19 and repel the exosomes. The sensor's limit of detection is close to a single virus owing to its transduction technique of quantum mechanical tunneling current. I will discuss COVID-19 electronic sensor performance and its performance along with its fabrication and applications in this talk.