Nanomaterial-Based Biosensors for SARS-CoV-2 and Future Epidemics

The outbreak of the coronavirus disease 2019 (COVID-19) pandemic has put enormous pressure on global healthcare and economic systems. The cause of this pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a positive-sense single-stranded RNA (+ssRNA) virus belonging to the beta family of coronaviruses. This highly contagious virus mainly spread through droplet transmission and contact transmission. People who are infected can release droplets and aerosol particles that contain the SARS-CoV-2 virus in the air when they exhale, cough, or sneeze. The droplets or aerosol particles of different sizes (from visible to microscopic) will continue to spread in the air or land on subjects. Healthy people may catch the virus via inhalation of aerosol particles from the air, or through the contact with contaminated surfaces before touching their nose, eyes, or mouth. Besides the direct droplet and contact transmissions, other viral transmission routes are also reported, such as spatter (e.g., blood spatter, spatter during intubation, etc.), fecal-eye transmission, nasal-eye transmission, mouth-eye transmission (through contaminated hands or objects) and the transmission of eye secretions and tears. In addition to its strong transmission power, SARS-CoV-2 can cause acute respiratory distress syndrome (ARDS), septic shock, coagulation dysfunction, intestinal dysfunction, and other clinical symptoms post-infection. Many people infected with COVID-19 display light symptoms like the common cold and influenza, and in some cases they are asymptomatic. Nevertheless, these asymptomatic carriers can still transmit SARS-CoV- 2, making the prevention of COVID-19 infection a major challenge in the world. In view of this, implementing fast, low-cost, accurate, easy-to-access, and integrated diagnostic devices available at the point of care (POC) is paramount to contain not only COVID-19, but also to cope with future epidemics.