Advancements in medical research: Exploring Fourier Transform Infrared (FTIR) spectroscopy for tissue, cell, and hair sample analysis

BACKGROUND

Fourier Transform Infrared (FTIR) spectroscopy has emerged as a powerful analytical tool in medical research, offering non-invasive and precise examination of the molecular composition of biological samples. The primary objective of this review is to underscore the benefits of FTIR spectroscopy in medicinal research, emphasizing its ability to delineate molecular fingerprints and assist in the identification of biochemical structures and key peaks in biological samples.

METHODS

This review comprehensively explores the diverse applications of FTIR spectroscopy in medical investigations, with a specific focus on its utility in analyzing tissue, cells, and hair samples. Various sources, including Google Scholar, PubMed, WorledCat and Scopus, were utilized to conduct this comprehensive literature review.

RESULTS

Recent advancements showcase the versatility of FTIR spectroscopy in elucidating cellular and molecular processes, facilitating disease diagnostics, and enabling treatment monitoring. Notably, FTIR spectroscopy has found significant utility in clinical assessment, particularly in screening counterfeit medicines, owing to its user-friendly operation and minimal sample preparation requirements. Furthermore, customs officials can leverage this technique for preliminary analysis of suspicious samples.

CONCLUSION

This review aims to bridge a gap in the literature and serve as a valuable resource for future research endeavors in FTIR spectroscopy within the medical domain. Additionally, it presents fundamental concepts of FTIR spectroscopy and spectral data interpretation, highlighting its utility as a tool for molecular analysis using Mid-Infrared (MIR) radiation.

Diagnosis of endometriosis using endometrioma volume and vibrational spectroscopy with multivariate methods as a noninvasive method

Endometriomas are typically an advanced form of endometriosis that leads to the formation of scar tissue, adhesions, and an inflammatory reaction. There is no certain serum marker for the diagnosis of endometriosis. This study aims to research the correlation between the amount of peaks corresponding to proteins and lipids with the volume of endometrioma and determine the chemical structure of blood serum collected from women suffering from endometriosis patients with endometrioma and healthy subjects using Fourier Transform Infrared (FTIR) spectroscopy. FTIR spectroscopy is used as a non-invasive diagnostic technique for the discrimination of endometriosis women with endometrioma and control blood sera. The FTIR spectra of 100 serum samples acquired from 50 patients and 50 healthy individuals were used for this study. For this purpose, multivariate analyses such as Principal Component Analysis (PCA), Partial Last Square analysis (PLS) with Variables Importance in Projection (VIP), and probability models, were performed. Our results showed that FTIR range 1500 cm^-1 and 1700 cm^-1 and around 2700 cm^-1 - 3000 cm^-1, regions may be used for the diagnosis of endometriosis. Also, we find that proteins and lipids fraction increase with the volume of endometrioma. Moreover, PLS and VIP analysis suggested that lipids could be helpful in the diagnosis of endometriosis women with endometrioma.

Raman spectral discrimination in human liquid biopsies of oesophageal transformation to adenocarcinoma

The aim of this study was to determine whether Raman spectroscopy combined with chemometric analysis can be applied to interrogate biofluids (plasma, serum, saliva and urine) towards detecting oesophageal stages through to oesophageal adenocarcinoma [normal/squamous epithelium, inflammatory, Barrett's, low-grade dysplasia, high-grade dysplasia and oesophageal adenocarcinoma (OAC)]. The chemometric analysis of the spectral data was performed using principal component analysis, successive projections algorithm or genetic algorithm (GA) followed by quadratic discriminant analysis (QDA). The genetic algorithm quadratic discriminant analysis (GA-QDA) model using a few selected wavenumbers for saliva and urine samples achieved 100% classification for all classes. For plasma and serum, the GA-QDA model achieved excellent accuracy in all oesophageal stages (>90%). The main GA-QDA features responsible for sample discrimination were: 1012 cm^-1 (C─O stretching of ribose), 1336 cm^-1 (Amide III and CH₂ wagging vibrations from glycine backbone), 1450 cm^-1 (methylene deformation) and 1660 cm^-1 (Amide I). The results of this study are promising and support the concept that Raman on biofluids may become a useful and objective diagnostic tool to identify oesophageal disease stages from squamous epithelium to OAC.

miR-205-5p inhibits human endometriosis progression by targeting ANGPT2 in endometrial stromal cells

BACKGROUND

miRNA expression profiles in ectopic endometrium (EC) serving as pathophysiologic genetic fingerprints contribute to determining endometriosis progression; however, the underlying molecular mechanisms remain unknown.

METHODS

miRNA microarray analysis was used to determine the expression profiling of EC fresh tissues. qRT-PCR was performed to screen miR-205-5p expression in EC tissues. The roles of miR-205-5p and its candidate target gene, angiopoietin-2 (ANGPT2), in endometriosis progression were confirmed on the basis of both in vitro and in vivo systems. miR-205-5p and ANGPT2 expression were measured by in situ hybridization and immunochemistry, and their clinical significance was statistically analysed.

RESULTS

miR-205-5p was screened as a novel suppressor of endometriosis through primary ectopic endometrial stromal cell migration, invasion, and apoptosis assay in vitro, along with endometrial-like xenograft growth and apoptosis in vivo. In addition, ANGPT2 was identified as a direct target of miR-205-5p through bioinformatic target prediction and luciferase reporter assay. Re-expression and knockdown of ANGPT2 could respectively rescue and simulate the effects induced by miR-205-5p. Importantly, the miR-205-5p-ANGPT2 axis was found to activate the ERK/AKT pathway in endometriosis. Finally, miR-205-5p and ANGPT2 expression were closely correlated with the endometriosis severity.

CONCLUSION

The newly identified miR-205-5p-ANGPT2-AKT/ERK axis illustrates the molecular mechanism of endometriosis progression and may represent a novel diagnostic biomarker and therapeutic target for disease treatment.

Fourier transform infrared and Raman-based biochemical profiling of different grades of pure foetal-type hepatoblastoma

The biomolecular events resulting from the progression of hepatoblastoma remain to be elucidated. Fourier-transform infrared (FTIR) and Raman spectroscopies are capable of noninvasively and accurately capturing the biochemical properties of biological tissue from its pathological status. Our aim was to probe critial biomolecular changes of liver accompanying the progression of pure foetal hepatoblastoma (PFH) by FTIR and Raman spectroscopies. Herein, biochemical alterations were both evident in the FTIR spectra (regions of 3100-2800 cm^-1 and 1800-900 cm^-1 ) and the Raman spectra (region of 1800-400 cm^-1 ) among normal, borderline and malignant liver tissues. Compared with normal tissues, the ratios of protein-to-lipid, α-helix-to-β-sheet, RNA-to-DNA, CH3 methyl-to-CH2 methylene, glucose-to-phospholipids, and unsaturated-to-saturated lipids intensities were significantly higher in malignant tissues, while the ratios of RNA-to-Amide II, DNA-to-Amide II, glycogen-to-cholesterol and Amide I-to-Amide II intensities were remarkably lower. These biochemical alterations in the transition from normal to malignant have profound implications not only for cyto-pathological classification but also for molecular understanding of PFH progression. The successive changes of the spectral characteristics have been shown to be consistent with the development of PFH, indicating that FTIR and Raman spectroscopies are excellent tools to interrogate the biochemical features of different grades of PFH.

Examination of cervical swabs of patients with endometriosis using Fourier transform infrared spectroscopy

PURPOSE

There is no established non-invasive method to diagnose patients with endometriosis. As a nondestructive type of radiation, infrared light might be used for discrimination by causing vibration of the covalent bonds of the molecules when absorbed by the tissues. The aim of the study was to test whether cervical swab can be used to diagnose women with endometriosis using Fourier transform infrared spectroscopy (FTIR).

METHODS

In this prospective case-control study, women between 18-45 years old and undergoing laparoscopy due to various reasons were recruited (n = 20). According to the findings during laparoscopy, patients were stratified as stage I-II or stage III-IV endometriosis groups. Women lacking any visible lesions of endometriosis were recruited as controls. A cervical swab was taken from all patients just before the surgical procedure and pulled into a tube containing saline solution. FTIR spectra were obtained and the fingerprint region (1750-850 cm^-1) was used for analyses.

RESULTS

Finally, three samples in stage I-II, five samples in stage III-IV and five samples in the control group were analyzed. Hierarchical cluster analysis and principal component analysis were performed as the chemometric method. A total of ten observable peaks were detected in the absorbance spectra of samples. The peaks at 1450 and 1405 cm^-1 originating from lipids and proteins significantly increased in the stage III-IV endometriosis group when compared with controls. In addition, nucleic acid/carbohydrate ratio was significantly lower in the stage I-II group indicating that the alteration of the carbohydrate level might be important.

CONCLUSIONS

Examination of cervical swab with FTIR spectroscopy might be a proper candidate for a non-invasive diagnostic approach of endometriosis.

Exposure to cadmium and mono-(2-ethylhexyl) phthalate induce biochemical changes in rat liver, spleen, lung and kidney as determined by attenuated total reflection-Fourier transform infrared spectroscopy

Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy is a label-free, non-destructive analytical technique for biochemical analysis of macromolecular components within tissue samples. Cadmium (Cd) and mono-(2-ethylhexyl) phthalate (MEHP), a primary metabolite of di-(2-ethylhexyl) phthalate, are present ubiquitously in the environment and in organisms, and have adverse impacts on ecosystems and human health. Herein we employed ATR-FTIR analysis to identify biomolecular changes in rat liver, spleen, lung and kidney after prepubertal exposure to Cd and MEHP. Our results showed clear segregations between the 3 mg/kg Cd-, 10 mg/kg, 50 mg/kg, 250 mg/kg MEHP- and binary mixture-treated groups vs. the solvent control group. Following principal components analysis coupled with linear discriminant analysis, biochemical alterations associated with different doses of Cd and MEHP were attributed mainly to lipids, proteins, phosphates and carbohydrates. In addition, the ratios of lipid/protein, C=O stretching/CH₂ methylene (lipid oxidation level), amide I/amide II, α-helix/β-sheet and CH₃ methyl/CH₂ methylene (acetylation level) in target organs were affected by these toxicants. There seems to be no dose-response effect of Cd and MEHP on target organs. We observed hardly any joint toxic action of these toxicants. This is the first study showing the application of ATR-FTIR spectroscopy to the assessment of toxicity of Cd and MEHP. Possibly, destruction of cell membrane structure and integrity could be the common mechanism of Cd and MEHP toxicity in liver, spleen, lung and kidney.

Attenuated total reflection Fourier-transform infrared spectral discrimination in human bodily fluids of oesophageal transformation to adenocarcinoma

Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) of biofluids was used to detect oesophageal stages through to oesophageal adenocarcinoma.

A novel use of infra-red spectroscopy (NIRS and ATR-FTIR) coupled with variable selection algorithms for the identification of insect species (Diptera: Sarcophagidae) of medico-legal relevance

Unequivocal identification of fly specimens is an essential requirement in forensic entomology. Herein, a simple, non-destructive and rapid method based on two vibrational spectroscopy techniques [Near-Infrared Spectroscopy (NIRS) and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy] coupled with variable selection techniques such as genetic algorithm-linear discriminant analysis (GA-LDA) and successive projection algorithm-linear discriminant analysis (SPA-LDA) were applied for identifying and discriminating six species of flesh flies (Diptera: Sarcophagidae) native to Neotropical regions. This novel approach is based on the unique spectral "fingerprints" of their biochemical composition. One hundred sixty (160) NIRS and FT-IR specimens (120 male, 40 female) were acquired; different pre-processing methods such as baseline correction, derivative and Savitzky-Golay smoothing were also performed. In addition, the multivariate classification accuracy results were tested based on sensitivity, specificity, positive (or precision) and negative predictive values, Youden index, positive and negative likelihood ratios. Principal components analysis (PCA) was employed for male vs. female category using NIRS, strongly showing the separation between the classes with only three principal components and 99% explained variance. Differentiation between the genera Oxysarcodexia, Peckia and Ravinia was efficiently confirmed by both techniques. In comparison with other biological methods, this approach represents an effective choice for fast and non-destructive identification in forensic entomology.

Valdecoxib Recovers the Lipid Composition, Order and Dynamics in Colon Cancer Cell Lines Independent of COX-2 Expression: An ATR-FTIR Spectroscopy Study

Prostanoids play an important role in a variety of physiological and pathophysiological processes including inflammation and cancer. The rate-limiting step in the prostanoid biosynthesis pathway is catalyzed by cyclooxygenases (COXs). Aberrant expression of the inducible isoform COX-2 plays a significant role in colon cancer initiation and progression. In this study, we have hypothesized that COX-2 specific inhibitors such as Valdecoxib (VLX), being highly hydrophobic, may alter biophysical properties of cellular lipids. In this study, COX-2 expressing (HT29) and COX-2 non-expressing (SW620) colon cancer cell lines were treated with VLX and examined using attenuated total reflection infrared spectroscopy. The results revealed that VLX treatment decreased lipid fluidity in the cells irrespective of COX-2 expression status and affected order parameters of the lipids in both cell lines. Cluster analysis also indicated that the spectral differences between the two cell lines are profound and could be successfully differentiated. Valdecoxib treatment could enhance the composition, order and dynamics of the lipids of colon cancer cells independently of its COX-2 inhibitory mechanism. Valdecoxib has therapeutic effects upon colon cancer, therefore it can be used as an adjuvant and/or chemopreventive agent for colon cancer.

Emerging technologies for biomedical analysis

Options for biomedical analysis continue to evolve from many fields of study, employing diverse detection and quantification methods. New technologies in this arena focus on improving the sensitivity of analysis and the speed of testing, as well as producing systems at low cost which can be used on site as a point-of-care device for telemedicine applications. In this article, the most important original experimental platforms as well as current commercial approaches to biomedical analysis are critically chosen and reviewed, covering January 2010 to January 2014. While literature is quite broad and numerous, there is clear emphasis on biological recognition and imaging for the most impactful works. The analytical approaches are discussed in terms of their utility in diagnostics and biomedical testing.

Comparison of transflection and transmission FTIR imaging measurements performed on differentially fixed tissue sections

FTIR microscopy of adjacent sections of tissue measured by transmission and transflection shows comparable images after UHCA.

Vibrational biospectroscopy coupled with multivariate analysis extracts potentially diagnostic features in blood plasma/serum of ovarian cancer patients

Despite numerous advances in "omics" research, early detection of ovarian cancer still remains a challenge. The aim of this study was to determine whether attenuated total reflection Fourier-transform infrared (ATR-FTIR) or Raman spectroscopy could characterise alterations in the biomolecular signatures of human blood plasma/serum obtained from ovarian cancer patients compared to non-cancer controls. Blood samples isolated from ovarian cancer patients (n = 30) and healthy controls (n = 30) were analysed using ATR-FTIR spectroscopy. For comparison, a smaller cohort of samples (n = 8) were analysed using an InVia Renishaw Raman spectrometer. Resultant spectra were pre-processed prior to being inputted into principal component analysis (PCA) and linear discriminant analysis (LDA). Statistically significant differences (P < 0.001) were observed between spectra of ovarian cancer versus control subjects for both biospectroscopy methods. Using a support vector machine classifier for Raman spectra of blood plasma, a diagnostic accuracy of 74% was achieved, while the same classifier showed 93.3% accuracy for IR spectra of blood plasma. These observations suggest that a biospectroscopy approach could be applied to identify spectral alterations associated with the presence of insidious ovarian cancer.

Measuring similarity and improving stability in biomarker identification methods applied to Fourier-transform infrared (FTIR) spectroscopy

FTIR spectroscopy is a powerful diagnostic tool that can also derive biochemical signatures of a wide range of cellular materials, such as cytology, histology, live cells, and biofluids. However, while classification is a well-established subject, biomarker identification lacks standards and validation of its methods. Validation of biomarker identification methods is difficult because, unlike classification, there is usually no reference biomarker against which to test the biomarkers extracted by a method. In this paper, we propose a framework to assess and improve the stability of biomarkers derived by a method, and to compare biomarkers derived by different method set-ups and between different methods by means of a proposed "biomarkers similarity index".

Feature selection strategies for identification of Staphylococcus aureus recovered in blood cultures using FT-IR spectroscopy successive projections algorithm for variable selection: a case study

Staphylococcus aureus is one of the leading causes of bacteremia, with high levels of accompanying morbidity and mortality. Current gold standard for the detection of S. aureus is very time-consuming, typically taking 24h or longer. We set out to determine whether Fourier-transform infrared spectroscopy (FT-IR) combined with variable selection techniques, such as, genetic algorithm-linear discriminant analysis (GA-LDA) and successive projection algorithm-linear discriminant analysis (SPA-LDA) could be applied to detect this pathogen of bloodstream infection in samples based on the unique spectral "fingerprints" of their biochemical composition. Thirty real blood samples from healthy volunteers were contaminated with five different concentrations (10(7) until 10(3) CFU/mL) of microorganism and it analyzed by IR spectroscopy. The resulting GA-LDA model successfully classified all test samples with respect to their concentration in contaminated blood using only 18 wavenumbers. Discriminant functions revealed that GA-LDA clearly segregated different microorganism concentrations and the variable selected confirmed the chemical entities associated with the microorganism. The current study indicates that IR spectroscopy with feature selection techniques have the potential to provide one rapid approach for whole-organism fingerprint diagnostic microbial directly in blood culture.

Changes in the infrared microspectroscopic characteristics of DNA caused by cationic elements, different base richness and single-stranded form

BACKGROUND

The infrared (IR) analysis of dried samples of DNA and DNA-polypeptide complexes is still scarce. Here we have studied the FT-IR profiles of these components to further the understanding of the FT-IR signatures of chromatin and cell nuclei.

METHODOLOGY/PRINCIPAL FINDINGS

Calf thymus and salmon testis DNA, and complexes of histone H1, protamine, poly-L-lysine and poly-L-arginine (histone-mimic macromolecules) with DNA were analyzed in an IR microspectroscope equipped with an attenuated total reflection diamond objective and Grams software. Conditions including polypeptides bound to the DNA, DNA base composition, and single-stranded form were found to differently affect the vibrational characteristics of the chemical groups (especially, PO(2)(-)) in the nucleic acid. The antisymmetric stretching (ν(as)) of the DNA PO(2)(-) was greater than the symmetric stretching (ν(s)) of these groups and increased in the polypeptide-DNA complexes. A shift of the ν(as) of the DNA PO(2)(-) to a lower frequency and an increased intensity of this vibration were induced especially by lysine-rich histones. Lysine richness additionally contributed to an increase in the vibrational stretching of the amide I group. Even in simple molecules such as inorganic phosphates, the vibrational characteristics of the phosphate anions were differently affected by different cations. As a result of the optimization of the DNA conformation by binding to arginine-rich polypeptides, enhancements of the vibrational characteristics in the FT-IR fingerprint could be detected. Although different profiles were obtained for the DNA with different base compositions, this situation was no longer verified in the polypeptide-DNA complexes and most likely in isolated chromatin or cell nuclei. However, the ν(as) PO(2)(-)/ν(s) PO(2)(-) ratio could discriminate DNA with different base compositions and DNA in a single-stranded form.

CONCLUSIONS/SIGNIFICANCE

FT-IR spectral profiles are a valuable tool for establishing the vibrational characteristics of individualized chromatin components, such as DNA and DNA-polypeptide complexes in dried samples.