The coronavirus disease 2019 (COVID-19) is the latest biological hazard for the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Even though numerous diagnostic tests for SARS-CoV-2 have been proposed, new diagnosis strategies are being developed, looking for less expensive methods to be used as screening. This study aimed to establish salivary vibrational modes analyzed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy to detect COVID-19 biological fingerprints that allow the discrimination between COVID-19 and healthy patients. Clinical dates, laboratories, and saliva samples of COVID-19 patients (N = 255) and healthy persons (N = 1209) were obtained and analyzed through ATR-FTIR spectroscopy. Then, a multivariate linear regression model (MLRM) was developed. The COVID-19 patients showed low SaO2, cough, dyspnea, headache, and fever principally. C-reactive protein, lactate dehydrogenase, fibrinogen, d-dimer, and ferritin were the most important altered laboratory blood tests, which were increased. In addition, changes in amide I and immunoglobulin regions were evidenced in the FTIR spectra analysis, and the MLRM showed clear discrimination between both groups. Specific salivary vibrational modes employing ATR-FTIR spectroscopy were established; moreover, the COVID-19 biological fingerprint in saliva was characterized, allowing the COVID-19 detection using an MLRM, which could be helpful for the development of new diagnostic devices.

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Some of the greatest challenges in stem cells (SCs) biology and regenerative medicine are differentiation control of SCs and ensuring the purity of differentiated cells. In this work, we differentiated mouse pluripotent stem cells (mPSCs) toward pancreatic cells characterizing this differentiation process by molecular and spectroscopic technics. Both mPSCs and Differentiated Pancreatic Cells (DPCs) were subjected to a genetic, phenotypic, and biochemical analysis by real-time quantitative PCR (RT-qPCR), immunocytochemistry, and Fourier Transform Infrared (FTIR) spectroscopy. Cultured mPCSs expressed pluripotent genes and proteins (Nanog and SOX2). DPCs expressed endodermal genes (SOX17 and Pdx1) at day 11, an inductor gene of embryonic pancreas development (Pdx1) at day 17 and pancreas genes and proteins (Insulin and Glucagon) at day 21 of differentiation. Likewise, FTIR spectra of mPSCs and DPCs at different maturation stages (11, 17, and 21 days) were obtained and showed absorption bands related with different types of biomolecules. These FTIR spectra exhibited significant spectral changes agreeing with the differentiation process, particularly in proteins and nucleic acids bands. In conclusion, the obtained DPCs passed through the chronological stages of embryonic pancreas development and FTIR spectra provide a new biophysical parameter based on molecular markers indicating the differentiation process of mPSCs to specialized cells.