Highly Sensitive Poly-N-isopropylacrylamide Microgel-based Electrochemical Biosensor for the Detection of SARS-COV-2 Spike Protein

OBJECTIVE: Late 2019 witnessed the outbreak and widespread transmission of coronavirus disease 2019 (COVID-19), a new, highly contagious disease caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Consequently, considerable attention has been paid to the development of new diagnostic tools for the early detection of SARS-CoV-2. METHODS: In this study, a new poly-N-isopropylacrylamide microgel-based electrochemical sensor was explored to detect the SARS-CoV-2 spike protein (S protein) in human saliva. The microgel was composed of a copolymer of N-isopropylacrylamide and acrylic acid, and gold nanoparticles were encapsulated within the microgel through facile and economical fabrication. The electrochemical performance of the sensor was evaluated through differential pulse voltammetry. RESULTS: Under optimal experimental conditions, the linear range of the sensor was 10(−13)–10(−9) mg/mL, whereas the detection limit was 9.55 fg/mL. Furthermore, the S protein was instilled in artificial saliva as the infected human saliva model, and the sensing platform showed satisfactory detection capability. CONCLUSION: The sensing platform exhibited excellent specificity and sensitivity in detecting spike protein, indicating its potential application for the time-saving and inexpensive detection of SARS-CoV-2.