Sers Signature of SARS-CoV-19 Infected Saliva and Nasopharyngeal Swabs: Towards Perspective COVID-19 Point-of-Care Diagnostics

In this study the intrinsic surface-enhanced Raman spectroscopy (SERS)-based approach coupled with chemometric analysis was adopted to establish the biochemical fingerprint of SARS-CoV-2 infected human fluids: saliva and nasopharyngeal swabs.The numerical methods, namely Partial Least-Squares Discriminant Analysis (PLS-DA) and Support Vector Machine Classification (SVMC) facilitated the spectroscopic identification of the viral-specific molecules, molecular changes, and/or distinct physiological signatures of pathetically altered fluids and thus enabled to developing the reliable classification model for fast identification and differentiation of negative CoV(-) and positive CoV(+) groups. The calculated diagnostic parameters for both methods (SVMC and PLS-DA) at the stage of preparation calibration model (calibration) and classification of external samples simulating real diagnostic conditions (validation) evinced higher accuracy, sensitivity, and specificity for saliva specimens.Here we outline the significant role of neopterin (associated with activity of macrophages and monocytes upon activation by interferon-gamma (IFN-γ) as the biomarker in the prediction of COVID-19 infection from nasopharyngeal swab. The saliva biochemical composition of SARS-CoV-2 infected samples CoV(+) is manifested by the specific oscillation in methionine and/or methionine adenosyl transferase. We have also observed the increased content of nucleic acids of DNA/RNA and proteins such as ferritin as well as specific immunoglobulins.At the current stage, the developed SERS for SARS-CoV-2 approach allows: (i) fast, simple and non-invasive collection of analyzed specimens; (ii) fast response with the time of analysis below 15 minutes, and (iii) sensitive and reliable SERS-based screening of COVID-19 disease.