Infrared characterization of spike protein of MERS-CoV, SARS-CoV, SARS-CoV-2 and its variants: first steps toward an optical biosensing device

In this work we introduce the first step toward the development of an Infrared (IR) sensoristic platform aiming to the detection and discrimination of airborne pathogens. SARS-CoV-2 Spike glycoprotein (S) is considered as a biomarker for virus recognition. A comparative spectroscopic analysis is illustrated, studying Spike glycoprotein subunit S1 from three different viruses, MERS-CoV, SARS-CoV and SARS-CoV-2. Moreover, SARS-CoV-2 variants are also investigated. The IR characterization of their S1 secondary conformation was carried out through Attenuated Total Reflection (ATR), analyzing the Amide I absorption band. In addition, pH-dependent conformational changes of SARS-CoV-2 S1 were investigated, too.