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Early diagnosis of COVID-19 in suspected patients is essential for contagion control and damage reduction strategies. We investigated the applicability of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy associated with machine learning in oropharyngeal swab suspension fluid to predict COVID-19 positive samples. The study included samples of 243 patients from two Brazilian States. Samples were transported by using different viral transport mediums (liquid 1 or 2). Clinical COVID-19 diagnosis was performed by the RT-PCR. We built a classification model based on partial least squares (PLS) associated with cosine k-nearest neighbours (KNN). Our analysis led to 84% and 87% sensitivity, 66% and 64% specificity, and 76.9% and 78.4% accuracy for samples of liquids 1 and 2, respectively. Based on this proof-of-concept study, we believe this method could offer a simple, label-free, cost-effective solution for high-throughput screening of suspect patients for COVID-19 in health care centres and emergency departments.

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Cortisol é um hormônio esteroide secretado pelo eixo Hipotálamo-Hipófise-Adrenal (HHA), relacionado ao funcionamento adrenal e responde diretamente aos estímulos estressores. O objetivo deste estudo foi quantificar o cortisol em sua forma hidrocortisona utilizando técnica de Espectroscopia de Infravermelho por Transformada de Fourier (ATR-FTIR). O pó da hidrocortisona foi diluído em formol e etanol na proporção de 1:1 e diluídos com água deionizada em seis pontos com range de 1 a 8ng/mL. As leituras foram realizadas com o espectrômetro Agilent Cary 630 para cada curva de diluição. Para análise estatística foram utilizados os pré-processamentos de suavização de Savitsky-Golay 21 pontos e 2ª ordem polinomial, e a correção de linha utilizada de Rubberband e PLSR para realização da curva de calibração. Resultados: A melhor região para análise de concentração da hidrocortisona foi entre 2800-3000cm-¹, responsável pelas ligações químicas entre CH2, CH3 e C-H em cadeias cíclicas. Através do PLSR foram obtidos resultados de predição de RMSE: 0,367 e R2: 0,96%. Os resultados deste estudo sugerem que é possível pela técnica de FTIR-ATR juntamente com a utilização do algoritmo de PLSR, fazer uma curva de calibração para a compreensão dos níveis de hidrocortisona em água.

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Breast cancer is a heterogeneous disease, and its spread involves a succession of clinical and pathological stages. Screening is predominantly based on mammography, which has critical limitations related to the effectiveness and production of false-positive or false-negative results, generating discomfort and low adherence. In this context, infrared with attenuated total reflection Fourier transform (ATR- FTIR) emerges as a non-destructive sample tool, non-invasive, label-free, low operating cost, requiring only a small amount of sample, including liquid plasma samples. We sought to evaluate the clinical applicability of ATR-FTIR in breast cancer screening. Results: ATR-FTIR spectroscopy through its highest potential spectral biomarker could distinguish, by liquid plasma biopsy, breast cancer patients and healthy controls, obtaining a sensitivity of 97%, specificity of 93%, ROC curve of 97% and a prediction accuracy of 94%. The main variance between the groups was mainly in the band 1511 cm −1 of the control group, 1502 and 1515 cm −1 of the cancer group, which are the peaks of the bands referring to proteins and amide II. Conclusion: ATR-FTIR spectroscopy have demonstrated to be a promising tool to breast cancer screening, given the time efficiency, cost of the approach, and high ability to distinguish between liquid plasma samples between healthy breast cancer and controls.