Clinical applications of spectroscopic techniques in conjunction with multivariate analysis in virus diagnosis

In view of the global pandemic that started in 2020, caused by COVID-19, the importance of the existence of fast, reliable, cheap diagnostic techniques capable of detecting the virus even in the first days of infection became evident. This review discusses studies involving the use of spectroscopic techniques in the detection of viruses in clinical samples. Techniques based on mid-infrared, near-infrared, Raman, and molecular fluorescence are explained and it was demonstrated how they can be used in conjunction with computational tools of multivariate analysis to build models capable of detecting viruses. Studies that used real clinical samples from 2011 to 2021 were analyzed. The results demonstrate the potential of the techniques in detecting viruses. Spectroscopic techniques, as well as chemometric techniques, were also explained. Viral diagnosis based on spectroscopy has interesting advantages compared to standard techniques such as: fast results, no need for reagents, non-destructiveness for the sample, no need for sample preparation, relatively low cost, among others. Several studies have corroborated the real possibility that, in the near future, we may have spectroscopic tools being successfully applied in viral diagnosis.

Determination of arsenic, cadmium, selenium, zinc and other trace elements in Bangladeshi fish and arsenic speciation study of Hilsa fish flesh and eggs: Implications for dietary intake

Exposure to As from drinking water and its impact on the health of the Bangladeshi population has received much attention. However, very little information is available regarding As exposure through consumption of fish, which is the main source of animal protein for the majority of Bangladeshis. In this study, concentrations of As, Cd, Pb, Mn Se and Zn in different types of fish, consumed by Bangladeshis, were determined using Inductively Coupled Plasma Mass Spectrometry. Daily intakes of the toxic elements As, Cd and Pb through fish consumption were estimated to be 31.8, 0.4 and 4.8 μg/day, respectively. Hilsa (Tenualosa ilisha) contained the highest concentrations of total As (mean ± SD was 2.55 ± 1.3 mg/kg; n = 15) among the fish analysed. However, toxic inorganic As species were not detected. The dominant As species in Hilsa fish were: dimethylarsenic acid, arsenobetaine and arsenosugars, at 69, 11 and 20% of total As, respectively. The high concentration of Cd detected in Hilsa eggs (average 278 ± 518 μg/kg; range 7.4–1725 μg/kg; n = 10) is of concern since this may have harmful effects on the development of embryos and lead to a decline in the Hilsa population or the quality of the fish. It can also be harmful to those who consume Hilsa eggs on a regular basis. Selenium was found to be highest in Shoal (Micropterus cataractae) fish and a type of small fish, and lowest in Mrigal (Cirrhinus cirrhosis). Small fish species contained Mn and Zn at 7.1- and 4.3-fold higher concentrations, respectively, compared to big fish species. Keski (Corica soborna), a small fish species, contained by far the highest concentrations of Mn (52 mg/kg) and Zn (140 mg/kg), although the concentration of As (1.4 mg/kg) in this fish was lower than that of several other fish species. Small fish species are often consumed whole, including the bones, and therefore the essential trace elements present are potentially bioavailable for cellular metabolism. Our study shows that the Bangladeshi population can easily meet their daily requirement of Se and Zn from consumption of fish such as Shoal fish (Se and Zn), Hilsa fish (Se and Zn) and Keski fish (Se and Zn). Consumption of small fish (such as Keski) and big fish (such as Hilsa) from Bangladesh can provide valuable sources of essential trace elements as part of a balanced diet and thus negate the need for supplements and biofortification of certain foods. Ours is a small study and a detailed total dietary intake and human biomonitoring studies, that includes coverage of different socio-economic groups, are needed in Bangladesh before giving people supplements or biofortified foods.

Non-invasive assessment of tissue oxygenation parameters in diabetic patients foot sole using near infrared spectroscopy

Background and Objective: Diabetic problems are more common in the lower extremity and linked with high mortality rate which affects public health system. The present study focused on monitoring the changes in tissue oxygenation concentrations using Near infrared spectroscopy system along with temperature and hardness of the foot tissues. Methods: Control subjects (without diabetes) and diabetic patients without neuropathy were selected for this study and three standard foot risk areas were considered. Standard induced ischemic stimulus was given to assess the response of the designed system and to analyze the changes in oxyhemoglobin and deoxyhemoglobin levels during venous occlusion. Results: Results showed significant differences in the tissue oxygenation index value in all three standard areas where oxygenation value at the foot areas were significantly low ( p < 0.05) in diabetic group as compared to control group. Also, significant difference were found in tissue hardness value when comparing between groups, where the diabetic group had significantly high ( p < 0.05) tissue hardness at area 5 and area 8 as compared to control groups. Conclusion: Therefore, the present study concludes that high tissue hardness had significant effect on tissue oxygenation index that affects vascular circulation and this condition could be assessable using NIRS technique in order to find risky areas at the foot sole.

Artificial intelligence analysis of FTIR and CD spectroscopic data for predicting and quantifying the length and content of protein secondary structures

Besides NMR and X-ray crystallography, FTIR and CD spectroscopy are widely considered to be useful for determining protein secondary structure. These techniques can be used to obtain data in few minutes, using small quantities of proteins, which make them amenable for proteomics research. Here we explore the possibility of using artificial intelligence techniques to simultaneously analyse both FTIR and CD spectroscopic data for an identical set of proteins. Neural network analysis was carried out on normalised regions of FTIR (1700-1600 cm−1) and CD (180-259 nm) spectral data both with and without boxcar averaging in order to quantify the average length and percentages of secondary structures. A hybrid genetic algorithm/neural network approach, that automatically selects structure-sensitive wavelength/frequency, was used for the quantification of the protein secondary structure. Using this algorithm we also successfully identified the region of the CD spectrum that contains the most structure-sensitive information. This was located between 214-251 nm, suggesting that this region alone may be sufficient to rapidly determine the secondary structure content from CD spectral data. Overall, CD spectroscopic analysis produced better results compared to FTIR spectroscopy when selected wavelengths were used, although FTIR was better when the entire region between 1700-1600 cm−1 (FTIR), and 180-259 nm (CD), was subjected to neural network analysis. Application of Adaptive Neuro-Fuzzy Inference System (ANFIS) with fuzzy subtractive clustering for the analysis of the spectral data led to a slightly better prediction of the average helix/sheet length for FTIR spectroscopy compared to CD. Our findings reveal the potential of using artificial intelligence techniques for not only extracting structural information but also for better understanding of the relationship between complex spectral data and biologically important information.

ATR-FTIR spectroscopy for virus identification: A powerful alternative

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.

Raman spectroscopy applications for the diagnosis and follow-up of type 2 diabetes mellitus. A brief review

Background: There is considerable interest in developing faster, less invasive, and more objective techniques to diagnose type 2 diabetes mellits (T2DM). Optical techniques like Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) are efficient, precise, low-cost, portable, and easy to handle, which seem to overcome most of the present difficulties of actual tests for T2DM diagnosis. However, the use of both Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) has been limited for T2DM diagnosis or follow-up. Objective: To gather information regarding the use of Raman spectroscopy and SERS to evaluate the spectra of biofluids (blood components, saliva, and urine) and tissues (skin) as an early diagnostic tool or follow-up for T2DM. Results: Skin and biofluids provide a great amount of information that can be analyzed by Raman spectroscopy and SERS. These optical techniques are excellent for clinical applications and can differentiate people with T2DM from healthy individuals, predict complications arising from T2DM (chronic kidney disease), and might be used to monitor glucose (glycemic control). Conclusion: Raman spectroscopy and SERS are good optical techniques for the diagnosis of T2DM in which sample preparation is not necessary or very simple, non-destructive, non-invasive, relatively fast to acquire, and low-cost.

Electron paramagnetic resonance (EPR) spectroscopy: Food, biomedical and pharmaceutical analysis

Electron paramagnetic resonance (EPR) spectroscopy can be applied as an effective and non-invasive spectroscopic method for analyzing samples with unpaired electrons. EPR is suitable for the quantification of radical species, assessment of redox chemical reaction mechanisms in foods, evaluation of the antioxidant capacity of food, as well as for the analysis of food quality, stability, and shelf life. It can be employed for evaluating and monitoring the drug release processes, in vitro and in vivo. EPR can be employed for the direct detection of free radical metabolites, and the evaluation of drug release mechanisms from biodegradable polymers; it can be employed for analyzing the drug antioxidant effects. Additionally, spatial resolution can be achieved through EPR-imaging. EPR spectroscopy and imaging have shown diverse applications in food, biomedical and pharmaceutical fields, and also more applications are predictable to emerge in the future. This review highlights recent advances and important challenges related to the application of EPR in food, biomedical and pharmaceutical analysis and assessment.

AFM force spectroscopy as a powerful tool to address material design for biomedical applications. A review

Force Spectroscopy (FS), which is one of the operating modes of Atomic Force Microscope (AFM) technique proven to be useful in many biological and medical applications, such as cancer cells recognition. Currently, many scientific institutions carry on research on the Young’s modulus of individual cancer cells in order to detect the disease at an early stage of its development. As a result of the growing interest in the use of force spectroscopy to study cells’ mechanic, this review summarizes new applications of this method to study changes in the physical and chemical properties of cells under the influence of external stimuli of different origins. The work is divided into four research areas, in which the use of AFM force spectroscopy was used to explain phenomena occurring at the early stages of intracellular organization changes. Research areas presented in this manuscript focuses on detailed description of the effect of manifold external stimuli on cells, such as: (i) cell aging, (ii) active ingredients used in the cosmetics industry to improve skin condition, (iii) nanoparticles used in biomedicine, and (iv) micro- and nano-structures of topography on the surface of substrates used for cell cultures. This review is based on a critical analysis of the latest literature reports (seven of which were created with Author’s contribution) describing the use of force spectroscopy as an effective tool to study the mechanical properties of living cells.