ATR-FTIR spectroscopy for virus identification: A powerful alternative

Abstract

In pandemic times, like the one we are witnessing for COVID-19, the discussion about new efficient and rapid techniques for diagnosis of diseases is more evident. In this mini-review, we present to the virological scientific community the potential of attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy as a diagnosis technique. Herein, we explain the operation of this technique, as well as its advantages over standard methods. In addition, we also present the multivariate analysis tools that can be used to extract useful information from the data towards classification purposes. Tools such as Principal Component Analysis (PCA), Successive Projections Algorithm (SPA), Genetic Algorithm (GA) and Linear and Quadratic Discriminant Analysis (LDA and QDA) are covered, including examples of published studies. Finally, the advantages and disadvantages of ATR-FTIR spectroscopy are emphasized, as well as future prospects in this field of study that is only growing. One of the main aims of this paper is to encourage the scientific community to explore the potential of this spectroscopic tool to detect changes in biological samples such as those caused by the presence of viruses.

Kirchhoff’s Thermal Radiation from Lithography-Free Black Metals

“…The atmospheric transmission window with between 3 and 4 μm wavelengths and slightly lower transmisivity at the 8–13 μm band can be utilised for radiative cooling [ 43 , 44 ] using simple black metal coatings studied in this work. Furthermore, radiation of heat into the 8–13 μm band spectral window where most of organic materials strongly absorb [ 45 , 46 , 47 , 48 ], e.g., protein (amide) and DNA/RNA bands common for silk, bacteria and viruses can be harnessed for enhancing biocidal functions of nanotextured materials. The IR emission of hot photo-excited electrons into the IR absorption band of photo-polymerisable resists is shown to contribute to 3D polymerisation when ultra-short laser pulses are used [ 49 ].…”

ATR-FTIR Spectrum Analysis of Saliva Samples from COVID-19 Positive Patients

“…Although ATR-FTIR is not used as a diagnosis technique, several authors have reported the use of FTIR spectroscopy for rapid detection of infective virus particles poliovirus in cell cultures [24], and Santos et al in 2020, reported several spectral features changes for hepatitis infected patients [17]. Therefore, in the search to propose new techniques that allow detecting the SARS-CoV-2 virus, FTIR spectroscopy has been considered in this research.…”

“…Moreover, saliva has a signi cant content of components, which show an intersection of its links, making it challenging to describe particular affectations of pathologies [16]. Currently, the problem of characterizing populations from FTIR spectra has been addressed using techniques commonly used in the area of machine learning; Santos et al have suggested the use of different methodologies that allow distinguishing between two or more groups of spectra based on the results obtained through them in different investigations [17]. Since there is no way to know which method would be the most appropriate to tackle a particular problem, some authors have suggested using regression models followed by more complex models such as vector support machines (SVM) or arti cial neural networks (ANN).…”

Towards the Direct Detection of Viral Materials at the Surface of Protective Face Masks via Infrared Spectroscopy

“…Typically, a variety of pre-processing steps are used to remove unwanted variance (i.e., variance not characteristic for the target analytes) from individual samples and numerically prepare data for modelling. 21 In all models described below, baseline correction, i.e., weighted least squares automatic baseline removal (AWLS, order = 2), and normalization (i.e., 1-norm/standard normal variate) were used to improve the signal-to-noise ratio (SNR) of the data and to adjust the baseline. In addition, applying the 1 st derivative Savitzky-Golay lter ( lter parameters: order = 2, window: 15 pt) as well as mean centering were used for pre-processing the spectra aiming at a possibly robust model.…”

“…Likewise, all biomolecules and even entire biological specimen absorb IR radiation providing potential for pinpointing biomaterials including, e.g., virus containing aerosols. 21 While IR spectroscopy is nowadays considered a routine tool for studying protein structure, 20 especially IR-ATR techniques enable the analysis of otherwise opaque samples (Figure 1A). 22 Alternatively and if a su cient signal strength may be obtained, IR-ERwhereby IR radiation is re ected off the external surface of a sample (Figure 1B) -may be applied, e.g., for direct particle analysis at a lter surface.…”