IR spectroscopy as a new tool for evidencing antitumor drug signatures

A technique based on infrared spectroscopy for determining sulfanilamide levels sustainably: Progress and comparisons of greenness and whiteness using ComplexGAPI, AGREE, and RGB

The study aimed to determine the potential of the infrared (IR) spectrophotometric technique for measuring the content of sulphanilamide with the sulfonamide group. The study aimed to obtain the IR spectra of sulfanilamide and use the -SO2 band at 1114.37 for the quantitative assay, determining its area under the curve (AUC). The study gives an alternative approach to existing analytical techniques that require vast amounts of organic solvents, which are costly and can be toxic, thus impacting the environment and increasing the analysis cost. The study evaluated the method's whiteness and greenness by utilizing the Complex green analytical procedure index, analytical GREEness calculator and Red Green Blue algorithm tool. The linierity was found to be 5 to 30 µg/ml. The present study has developed an infrared (IR) spectroscopic method that employs a straightforward sample preparation technique in methanol. The IR spectroscopic method's linearity range was determined to be 5-30 µg/ml. The p-value was 0.001 at 95 % confidence level assuring better recovery. This method is evaluated according to the Q2R1 ICH guideline. It is applicable to routine quality control analysis without pre-extraction using green IR spectroscopy. In conclusion, the study demonstrated that IR spectrophotometric techniques can quantify sulfanilamide while reducing the use of organic solvents, contributing to the green-and-white analytical chemistry approach. The developed methods are reliable, accurate, and cost-effective and have the potential to be implemented in routine analysis of sulfanilamide.

Investigating the biochemical response of proton minibeam radiation therapy by means of synchrotron-based infrared microspectroscopy

The biology underlying proton minibeam radiation therapy (pMBRT) is not fully understood. Here we aim to elucidate the biological effects of pMBRT using Fourier Transform Infrared Microspectroscopy (FTIRM). In vitro (CTX-TNA2 astrocytes and F98 glioma rat cell lines) and in vivo (healthy and F98-bearing Fischer rats) irradiations were conducted, with conventional proton radiotherapy and pMBRT. FTIRM measurements were performed at ALBA Synchrotron, and multivariate data analysis methods were employed to assess spectral differences between irradiation configurations and doses. For astrocytes, the spectral regions related to proteins and nucleic acids were highly affected by conventional irradiations and the high-dose regions of pMBRT, suggesting important modifications on these biomolecules. For glioma, pMBRT had a great effect on the nucleic acids and carbohydrates. In animals, conventional radiotherapy had a remarkable impact on the proteins and nucleic acids of healthy rats; analysis of tumour regions in glioma-bearing rats suggested major nucleic acid modifications due to pMBRT.

Exploring the in vitro potential of royal jelly against glioblastoma and neuroblastoma: impact on cell proliferation, apoptosis, cell cycle, and the biomolecular content

Neuroblastoma and glioblastoma are the most commonly seen nervous system tumors, and their treatment is challenging. Relatively safe and easy acquisition of nutraceutical natural products make them suitable candidates for anticancer research. Royal jelly (RJ), a superfood, has many biological and pharmacological activities. This study was conducted to, for the first time, elucidate its anticancer efficiency, even in high doses, on neuroblastoma and glioblastoma cell lines through cell viability, apoptosis, cell cycle and biomolecular content evaluation. We performed experiments with RJ concentrations in the range of 1.25-10 mg mL-1 for 48 h. Cell viability assays revealed a notable cytotoxic effect of RJ in a concentration-dependent manner. Treatment with a high dose of RJ significantly increased the apoptotic cell population of both cell lines. Furthermore, we observed G0-G1 phase arrest in neuroblastoma cells but G2-M arrest in glioblastoma cells. All these cellular changes are closely associated with the alterations of the macromolecular makeup of the cells, such as decreased saturated lipid, protein, DNA and RNA amounts, protein conformational changes, decreased protein phosphorylation and increased protein carbonylation. These cellular changes are associated with RJ triggered-ROS formation. The clear segregation between the control and the RJ-treated groups proved these changes, obtained from the unsupervised and supervised chemometric analysis. RJ has good anticancer activity against nervous system cancers and could be safely used with current treatment strategies.

Biomolecular fingerprints of the effect of zoledronic acid on prostate cancer stem cells: Comparison of 2D and 3D cell culture models

Revealing the potential of candidate drugs against different cancer types without disrupting normal cells depends on the drug mode of action. In the current study, the drug response of prostate cancer stem cells (PCSCs) to zoledronic acid (ZOL) grown in two-dimensional (2D) and three-dimensional (3D) culture systems was compared using Fourier transform-infrared (FT-IR) spectroscopy which is a vibrational spectroscopic technique, supporting by biochemical assays and imaging techniques. Based on our data, in 2D cell culture conditions, the ZOL treatment of PCSCs isolated according to both C133 and CD44 cell surface properties induced early/late apoptosis and suppressed migration ability. The CD133 gene expression and protein levels were altered, depending on culture systems. CD133 expression was significantly reduced in 2D cells upon ZOL treatment. FT-IR data revealed that the integrity, fluidity, and ordering/disordering states of the cell membrane and nucleic acid content were altered in both 2D and 3D cells after ZOL treatment. Regular protein structures decrease in 2D cells while glycogen and protein contents increase in 3D cells, indicating a more pronounced cytotoxic effect of ZOL for 2D cells. Untreated 3D PCSCs exhibited an even different spectral profile associated with IR signals of lipids, proteins, nucleic acids, and glycogen in comparison to untreated 2D cells. Our study revealed significant differences in the drug response and cellular constituents between 2D and 3D cells. Exploring molecular targets and/or drug-action mechanisms is significant in cancer treatment approaches; thus, FT-IR spectroscopy can be successfully applied as a novel drug-screening method in clinical research.

A Brief Review of FT-IR Spectroscopy Studies of Sphingolipids in Human Cells

In recent years, sphingolipids have attracted significant attention due to their pivotal role in cellular functions and physiological diseases. A valuable tool for investigating the characteristics of sphingolipids can be represented via FT-IR spectroscopy, generally recognized as a very powerful technique that provides detailed biochemical information on the examined sample with the unique properties of sensitivity and accuracy. In the present paper, some fundamental aspects of sphingolipid components of human cells are summarized, and the most relevant articles devoted to the FT-IR spectroscopic studies of sphingolipids are revised. A short description of different FT-IR experimental approaches adopted for investigating sphingolipids is also given, with details about the most commonly used data analysis procedures. The present overview of FT-IR investigations, although not exhaustive, attests to the relevant role this vibrational technique has played in giving significant insight into many aspects of this fascinating class of lipids.

Untargeted Metabolomics Reveals Lipid Impairment in the Liver of Adult Zebrafish (Danio rerio) Exposed to Carbendazim

Carbendazim is a systemic fungicide used in several countries, particularly in Brazil. However, studies suggest that it is related to the promotion of tumors, endocrine disruption, and toxicity to organisms, among other effects. As a result, carbendazim is not allowed in the United States, Australia, and some European Union countries. Therefore, further studies are necessary to evaluate its effects, and zebrafish is a model routinely used to provide relevant information regarding the acute and long-term effects of xenobiotics. In this way, zebrafish water tank samples (water samples from aquari containing zebrafish) and liver samples from animals exposed to carbendazim at a concentration of 120 μg/L were analyzed by liquid chromatography coupled to high-resolution mass spectrometry, followed by multivariate and univariate statistical analyses, using the metabolomics approach. Our results suggest impairment of lipid metabolism with a consequent increase in intrahepatic lipids and endocrine disruption. Furthermore, the results suggest two endogenous metabolites as potential biomarkers to determine carbendazim exposure. Finally, the present study showed that it is possible to use zebrafish water tank samples to assess the dysregulation of endogenous metabolites to understand biological effects. Environ Toxicol Chem 2023;42:437-448. © 2022 SETAC.

Microfluidic nanodevices for drug sensing and screening applications

The outbreak of pandemics (e.g., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 in 2019), influenza A viruses (H1N1 in 2009), etc.), and worldwide spike in the aging population have created unprecedented urgency for developing new drugs to improve disease treatment. As a result, extensive efforts have been made to design novel techniques for efficient drug monitoring and screening, which form the backbone of drug development. Compared to traditional techniques, microfluidics-based platforms have emerged as promising alternatives for high-throughput drug screening due to their inherent miniaturization characteristics, low sample consumption, integration, and compatibility with diverse analytical strategies. Moreover, the microfluidic-based models utilizing human cells to produce in-vitro biomimetics of the human body pave new ways to predict more accurate drug effects in humans. This review provides a comprehensive summary of different microfluidics-based drug sensing and screening strategies and briefly discusses their advantages. Most importantly, an in-depth outlook of the commonly used detection techniques integrated with microfluidic chips for highly sensitive drug screening is provided. Then, the influence of critical parameters such as sensing materials and microfluidic platform geometries on screening performance is summarized. This review also outlines the recent applications of microfluidic approaches for screening therapeutic and illicit drugs. Moreover, the current challenges and the future perspective of this research field is elaborately highlighted, which we believe will contribute immensely towards significant achievements in all aspects of drug development.

High-sensitivity hyperspectral vibrational imaging of heart tissues by mid-infrared photothermal microscopy

Visualizing the spatial distribution of chemical compositions in biological tissues is of great importance to study fundamental biological processes and origin of diseases. Raman microscopy, one of the label-free vibrational imaging techniques, has been employed for chemical characterization of tissues. However, the low sensitivity of Raman spectroscopy often requires a long acquisition time of Raman measurement or a high laser power, or both, which prevents one from investigating large-area tissues in a nondestructive manner. In this work, we demonstrated chemical imaging of heart tissues using mid-infrared photothermal (MIP) microscopy that simultaneously achieves the high sensitivity benefited from IR absorption of molecules and the high spatial resolution down to a few micrometers. We successfully visualized the distributions of different biomolecules, including proteins, phosphate-including proteins, and lipids/carbohydrates/amino acids. Further, we experimentally compared MIP microscopy with Raman microscopy to evaluate the sensitivity and photodamage to tissues. We proved that MIP microscopy is a highly sensitive technique for obtaining vibrational information of molecules in a broad fingerprint region, thereby it could be employed for biological and diagnostic applications, such as live-tissue imaging.

Quantification of clinical mAb solutions using Raman spectroscopy: Macroscopic vs microscopic analysis

Raman Spectroscopy is well emerged in the field of Analytical Quality Control (AQC) as a rapid and cost-effective technique useful in many applications. The advantage of Raman spectroscopy is the non-invasiveness of measurements that enablesto analyse samples directly in its container. In this study, the potential of Raman spectroscopy was investigated for analysis of clinical preparations of mAbs. Three commercial formulations of monoclonal antibodies (mAbs) Avastin®, Ontruzant® and Tecentriq® corresponding to Bevacizumab (BVC), Trastuzumab (TRS) and Atezolizumab (ATZ) respectively, were analysed in quartz cuvette in macroscopic analysis and through the wall of perfusion bags in microscopic analysis. The spectra have been compared to those of excipients (trehalose and sucrose) and of γ-Globulin, in order to investigate the origin of Raman bands. As expected, Raman spectra were a combination of bands from monoclonal antibodies and correspoding excipients found in formulas. For quantitative analysis of the solutions, models have been constructed using Partial Least Square Regression (PLSR) with Leave K-Out Cross Validation (LKOCV). The quantification performance was comparable for both macroscopic and microscopic analysis, in terms of error and linearity. The results are thus promising for future AQC in situ, in perfusion bags.

Identifying traumatic brain injury (TBI) by ATR-FTIR spectroscopy in a mouse model

Traumatic brain injury (TBI) is one of the most common mechanical injuries and plays a significant role in forensic practice. For cadavers, however, accurate diagnosis of TBI becomes a more and more challenging task as the level of decomposition increases. Our main purpose was to investigate whether TBI in putrefied mouse cadavers can be identified by Fourier Transform Infrared (FT-IR). The method proposed by Feeney et al. was used to establish the mouse TBI model. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) modeling were used to distinguish fresh and putrefied brain tissues. Then, we established two PLS-DA models to identify injured area samples in fresh and putrefied brain tissue samples. The accuracy of the two models were 100% and 92.5%. Our preliminary research has proved that the use of FT-IR spectroscopy combined with chemometrics can identify TBI more quickly and accurately in cadavers, providing crucial evidence for judicial proceedings.

Soft threshold partial least squares predicts the survival fraction of malignant glioma cells against different concentrations of methotrexate's derivatives

Chemotherapy appeared to be a significant advancement in cancer research, with fewer side effects. Methotrexate (MTX) is a widely used anticancer drug with strong activity but serious side effects. Several MTX derivatives have been reported, with modifications at various sites to reduce side effects and increase efficacy. The current study uses FTIR spectroscopy to predict the survival fraction of human malignant glioma U87 (MG-U87) cell lines against MTX derivatives. Together with Parent MTX several aldehydes viz. Benzaldehyde, Chlorobenzaldehyde, 2-Chlorobenzaldehyde, 3-Nitrobenzaldehyde, 5-Chloro-2-hydroxybenz-aldehyde, 2-Hydroxy-5-Nitrobenzaldehyde, 2-Thiocarboxyaldehyde, Trans-2-pentenal, and Glutaraldehyde are treated with MTX to obtain MTX derivatives. The prediction of survival fraction of malignant glioma cells is carried out by Lasso, Elastic net and Soft PLS at different concentration levels of synthesized derivatives, including 400 μM, 200 μM, 100 μM, 50 μM, 25 μM and 12.5 μM. The cross-validated prediction error is minimised to optimise spectral wavelength selection and model parameters. It appears that the RMSE computed from test data is significantly varying with the change of models (p = 0.012), with the change of concentrations levels (p \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\le 0.001$$\end{document}≤0.001) and with the change of combination of models and concentration level (p \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\le 0.001$$\end{document}≤0.001). StPLS outperforms in predicting survival fraction of glioma cells at the concentration level 50 μM, 100 μM and 400 μM respectively with relative RMSE = 0.1,0.14 and 0.55. Lasso outperforms at the concentration level 12.5 μM, and 200 μM respectively with relative RMSE = 0.4 and 0.14. Elastic net outperforms at the concentration level 25 μM with relative RMSE = 0.8. Consistently appeared influential wavelength identifies the influential functional compounds which best predicts the survival fraction. Hence FTIR appears potential candidate for estimating survival fraction of MTX derivatives.

Synchrotron-Based Fourier-Transform Infrared Micro-Spectroscopy (SR-FTIRM) Fingerprint of the Small Anionic Molecule Cobaltabis(dicarbollide) Uptake in Glioma Stem Cells

The anionic cobaltabis (dicarbollide) [3,3'-Co(1,2-C2B9H11)2]-, [o-COSAN]-, is the most studied icosahedral metallacarborane. The sodium salts of [o-COSAN]- could be an ideal candidate for the anti-cancer treatment Boron Neutron Capture Therapy (BNCT) as it possesses the ability to readily cross biological membranes thereby producing cell cycle arrest in cancer cells. BNCT is a cancer therapy based on the potential of 10B atoms to produce α particles that cross tissues in which the 10B is accumulated without damaging the surrounding healthy tissues, after being irradiated with low energy thermal neutrons. Since Na[o-COSAN] displays a strong and characteristic ν(B-H) frequency in the infrared range 2.600-2.500 cm-1, we studied the uptake of Na[o-COSAN] followed by its interaction with biomolecules and its cellular biodistribution in two different glioma initiating cells (GICs), mesenchymal and proneural respectively, by using Synchrotron Radiation-Fourier Transform Infrared (FTIR) micro-spectroscopy (SR-FTIRM) facilities at the MIRAS Beamline of ALBA synchrotron light source. The spectroscopic data analysis from the bands in the regions of DNA, proteins, and lipids permitted to suggest that after its cellular uptake, Na[o-COSAN] strongly interacts with DNA strings, modifies proteins secondary structure and also leads to lipid saturation. The mapping suggests the nuclear localization of [o-COSAN]-, which according to reported Monte Carlo simulations may result in a more efficient cell-killing effect compared to that in a uniform distribution within the entire cell. In conclusion, we show pieces of evidence that at low doses, [o-COSAN]- translocates GIC cells' membranes and it alters the physiology of the cells, suggesting that Na[o-COSAN] is a promising agent to BNCT for glioblastoma cells.

Biomolecular changes and subsequent time-dependent recovery in hippocampal tissue after experimental mild traumatic brain injury

Traumatic brain injury (TBI) is the main cause of disability and mortality in individuals under the age of 45 years. Elucidation of the molecular and structural alterations in brain tissue due to TBI is crucial to understand secondary and long-term effects after traumatic brain injury, and to develop and apply the correct therapies. In the current study, the molecular effects of TBI were investigated in rat brain at 24 h and 1 month after the injury to determine acute and chronic effects, respectively by Fourier transform infrared imaging. This study reports the time-dependent contextual and structural effects of TBI on hippocampal brain tissue. A mild form of TBI was induced in 11-week old male Sprague Dawley rats by weight drop. Band area and intensity ratios, band frequency and bandwidth values of specific spectral bands showed that TBI causes significant structural and contextual global changes including decrease in carbonyl content, unsaturated lipid content, lipid acyl chain length, membrane lipid order, total protein content, lipid/protein ratio, besides increase in membrane fluidity with an altered protein secondary structure and metabolic activity in hippocampus 24 h after injury. However, improvement and/or recovery effects in these parameters were observed at one month after TBI.

In situ Analytical Quality Control of chemotherapeutic solutions in infusion bags by Raman spectroscopy

Analytical Quality Control (AQC) in centralised preparation units of oncology centers is a common procedure relying on the identification and quantification of the prepared chemotherapeutic solutions for safe intravenous administration to patients. Although the use of Raman spectroscopy for AQC has gained much interest, in most applications it remains coupled to a flow injection analyser (FIA) requiring withdrawal of the solution for analysis. In addition to current needs for more rapid and cost-effective analysis, the risk of exposure of clinical staff to the toxic molecules during daily handling is a serious concern to address. Raman spectroscopic analysis, for instance by Confocal Raman Microscopy (CRM), could enable direct analysis (non-invasive) for AQC directly in infusion bags. In this study, 3 anticancer drugs, methotrexate (MTX), 5-fluorouracil (5-FU) and gemcitabine (GEM) have been selected to highlight the potential of CRM for withdrawal free analysis. Solutions corresponding to the clinical range of each drug were prepared in 5% glucose and data was collected from infusion bags placed under the Raman microscope. Firstly, 100% discrimination has been obtained by Partial Least Squares Discriminant Analysis (PLS-DA) confirming that the identification of drugs can be performed. Secondly, using Partial Least Squares Regression (PLSR), quantitative analysis was performed with mean % error of predicted concentrations of respectively 3.31%, 5.54% and 8.60% for MTX, 5-FU and GEM. These results are in accordance with the 15% acceptance criteria used for the current clinical standard technique, FIA, and the Limits of Detection for all drugs were determined to be substantially lower than the administered range, thus highlighting the potential of confocal Raman spectroscopy for direct analysis of chemotherapeutic solutions.

Biomolecular alterations in acute traumatic brain injury (TBI) using Fourier transform infrared (FTIR) imaging spectroscopy

Acute injury is one of the substantial stage post-traumatic brain injury (TBI) occurring at the moment of impact. Decreased metabolism, unregulated cerebral blood flow and direct tissue damage are triggered by acute injury. Understating the biochemical alterations associated with acute TBI is critical for brain plasticity and recovery. The objective of this study was to investigate the biochemical and molecular changes in hippocampus, corpus callosum and thalamus brain regions post-acute TBI in rats. Fourier Transform Infrared (FTIR) imaging spectroscopy were used to collect chemical images from control and 3 hrs post-TBI (Marmarou model was used for the TBI induction) rat brains and adjacent sections were treated by hematoxylin and eosin (H&E) staining to correlate with the disruption in tissue morphology and injured brain biochemistry. Our results revealed that the total lipid and total protein content decreased significantly in the hippocampus, corpus callosum and thalamus after brain injury. Reduction in lipid acyl chains (-CH₂) associated with an increase in methyl (-CH₃) and unsaturated lipids olefin = CH concentrations is observed. Furthermore, there is a decrease in the lipid order (disorder), which leads to an increase in acyl chain fluidity in injured rats. The results suggest acute TBI damages brain tissues mechanically rather than chemical alterations. This will help in assessing successful therapeutic strategy in order to mitigate tissue damage in acute TBI period.

Study of the intracellular nanoparticle-based radiosensitization mechanisms in F98 glioma cells treated with charged particle therapy through synchrotron-based infrared microspectroscopy

The use of nanoparticles (NP) as dose enhancers in radiotherapy (RT) is a growing research field. Recently, the use of NP has been extended to charged particle therapy in order to improve the performance in radioresistant tumors. However, the biological mechanisms underlying the synergistic effects involved in NP-RT approaches are not clearly understood. Here, we used the capabilities of synchrotron-based Fourier Transform Infrared Microspectroscopy (SR-FTIRM) as a bio-analytical tool to elucidate the NP-induced cellular damage at the molecular level and at a single-cell scale. F98 glioma cells doped with AuNP and GdNP were irradiated using several types of medical ion beams (proton, helium, carbon and oxygen). Differences in cell composition were analyzed in the nucleic acids, protein and lipid spectral regions using multivariate methods (Principal Component Analysis, PCA). Several NP-induced cellular modifications were detected, such as conformational changes in secondary protein structures, intensity variations in the lipid CHx stretching bands, as well as complex DNA rearrangements following charged particle therapy irradiations. These spectral features seem to be correlated with the already shown enhancement both in the DNA damage response and in the reactive oxygen species (ROS) production by the NP, which causes cell damage in the form of protein, lipid, and/or DNA oxidations. Vibrational features were NP-dependent due to the NP heterogeneous radiosensitization capability. Our results provided new insights into the molecular changes in response to NP-based RT treatments using ion beams, and highlighted the relevance of SR-FTIRM as a useful and precise technique for assessing cell response to innovative radiotherapy approaches.

Differentiating Between Malignant Mesothelioma and Other Pleural Lesions Using Fourier Transform Infrared Spectroscopy

Histopathology, despite being the gold standard as a diagnostic tool, does not always provide a correct diagnosis for different pleural lesions. Although great progress was made in this field, the problem to differentiate between reactive and malignant pleural lesions still stimulates the search for additional diagnostic tools. Our research using vibrational spectroscopy and principal component analysis (PCA) statistical modeling represents a potentially useful tool to approach the problem. The objective method this paper explores is based on the correlation between different types of pleural lesions and their vibrational spectra. Obtained tissue spectra recorded by infrared spectroscopy allowed us to categorize spectra in different groups using a created PCA statistical model. The PCA model was built using tissues of known pathology as the model group. The validation samples were then used to confirm the functionality of our PCA model. Student's t-test was also used for comparing samples in paired groups. The PCA model was able to clearly differentiate the spectra of mesothelioma, metastasis and reactive changes (inflammation), and place them in discrete groups. Thus, we showed that Fourier transform infrared spectroscopy combined with PCA can differentiate pleural lesions with high sensitivity and specificity. This new approach could contribute in objectively differentiating specific pleural lesions, thus helping pathologists to better diagnose difficult pleural samples but also could shed additional light into the biology of malignant pleural mesothelioma.

Identifying the Responses from the Estrogen Receptor-Expressed MCF7 Cells Treated in Anticancer Drugs of Different Modes of Action Using Live-Cell FTIR Spectroscopy

Recently, we have shown that changes in Fourier transform infrared (FTIR) spectra of living MDA-MB-231 cells (a triple negative cell line) upon exposure to anticancer drugs reflect the changes in the cellular compositions which are correlated to the modes of action of drugs. In the present study, MCF7 cells (an estrogen receptor expressing breast cancer cell line) were exposed to three anticancer drugs belonging to two well-characterized anticancer classes: selective estrogen receptor modulators (SERMs) and DNA-intercalating agent. First, we evaluated if the changes in the spectrum of cells are according to the modes of action of drugs and the characteristics of the MCF7 cell line in the same way as the MDA-MB-231 cell. Living MCF7 cells were treated in the three drugs at half maximal inhibitory concentration (IC50), and the difference spectra were analyzed using principal component analysis (PCA). The results demonstrated clear separation between tamoxifen/toremifene (SERM)-treated cells from the doxorubicin (DNA-intercalator)-treated and untreated cells (control). Tamoxifen and toremifene induced similar spectral changes in the cellular compositions of MCF7 cells and lead to the clustering of these two drugs in the same quadrant of the principal component 1 (PC1) versus PC2 score plots. The separation is mostly attributed to their similar modes of actions. However, doxorubicin-treated MCF7 cells highlighted spectral changes that mainly occur in bands at 1085 and 1200-1240 cm^-1, which could be associated with the DNA-intercalation effects of the drug. Second, the pairwise PCA at various individual time points was employed to investigate whether the spectral changes of MCF7 and MDA-MB-231 cells in response to the IC50 of tamoxifen/toremifene and doxorubicin are dependent on the characteristics of the cell lines. The estrogen-expressing MCF7 cells demonstrated significant differences in response to the SERMs in comparison to the triple negative MDA-MB-231 cells, suggesting that different modes of action have taken place in the two tested cell lines. In contrast, the doxorubicin-treated MDA-MB-231 and MCF7 cells show similar changes in 1150-950 cm^-1, which indicates that the DNA intercalation effect of doxorubicin is found in both cell lines. The results have demonstrated that live-cell FTIR analysis is sensitive to the different modes of action from the same drugs on cells with different characteristics.

Prostate and breast cancer cells death induced by xanthohumol investigated with Fourier transform infrared spectroscopy

Fourier Transform Infrared spectroscopy was applied to detect in vitro cell death induced in prostate (PC-3) and breast (T47D) cancer cell lines treated with xanthohumol (XN). After incubation of the cancer cells with XN, specific spectral shifts in the infrared spectra arising from selected cellular components were identified that reflected biochemical changes characteristic for apoptosis and necrosis. Detailed analysis of specific absorbance intensity ratios revealed the compositional changes in the secondary structure of proteins and membrane lipids. In this study, for the first time we examined the changes in these molecular components and linked them to deduce the involvement of molecular mechanisms in the XN-induced death of the selected cancer cells. We showed that XN concentration-dependent changes were attributed to phospholipid ester carbonyl groups, especially in the case of T47D cells, suggesting that XN acts as an inhibitor of cell proliferation. Additionally, we observed distinct changes in the region assigned to the absorption of DNA, which were correlated with a specific marker of cell death and dependent on the XN dose and the type of cancer cells. The microscopic observation and flow cytometry analysis revealed that the decrease in cancer cell viability was mainly related to the induction of necrotic cell death. Moreover, the T47D cells were slightly more sensitive to XN than the PC-3 cells. Considering the results obtained, it can be assumed that apoptosis and necrosis induced by XN may contribute to the anti-proliferative and cytotoxic properties of this flavonoid against cancer cell lines PC-3 and T47D.

Pterostilbene administration improves the recovery potential of extremely low-frequency magnetic field in acute renal ischemia-reperfusion injury: an FTIR spectroscopic study

Renal ischemia-reperfusion (I/R) injury, one of the drastic outcomes of renal failure and organ transplantation, tends to deteriorate over time; therefore, noninvasive therapeutic strategies will avail the progression-free survival of the patients. Magnetic field has been proposed as a noninvasive treatment strategy; however, with recent scientific advances, many controversies have arisen regarding its efficacy. Pterostilbene, a natural analog of resveratrol, was documented to be effective in treatment of I/R injuries. This study aims to assess the acute therapeutic effects of combined extremely low-frequency magnetic field (ELF-MF) and pterostilbene treatment on renal I/R injury. After induction of renal I/R in Wistar rats, treatments of 50 Hz, 1 mT ELF-MF applied alone or in combination with pterostilbene were applied for 5 consecutive days. Kidney homogenates were analyzed by Fourier transform infrared spectroscopy. I/R injury resulted in an altered protein and lipid structure with the dominance of longer acyl chains; a slight decrease in lipid, protein, unsaturated lipid, and unsaturated/saturated lipid content; and an increase in membrane fluidity and lipid peroxidation in rat kidneys. Although ELF-MF treatment alone was not sufficient to restore all ischemia-induced alterations, the combined treatment strategy of pterostilbene administration in the presence of ELF-MF was successful and warrants further investigation.

Real-time redox monitoring of a nitrosyl ruthenium complex acting as NO-donor agent in a single A549 cancer cell with multiplex Fourier-transform infrared microscopy

Multiplex Fourier-transform infrared microscopy (μFT-IR) helped to monitor trans-[Ru(NO) (NH₃)₄ (isn)]³⁺(I), uptake by A549 lung carcinoma cell, as well as the generation of its product, nitric oxide (NO), inside the cell. Chronoamperometry with NO-sensor and μFT-IR showed that exogenous NADH and the A549 cell induced the NO release redox mechanism. Chemical imaging confirmed that (I) was taken up by the cell, and that its localization coincided with its consumption in the cellular environment within 15 min of exposure. The Ru-NO absorption band in the IR spectrum shifted from 1932 cm^-1, when NO was coordinated to Ru as {Ru^II-NO⁺}³⁺, to 1876 cm^-1, due the formation of reduced species {Ru^II-NO⁰}²⁺, a precursor of NO release. Futhermore, the μFT-IR spectral profile demonstrated that, as a result of the NO action on the target, NO interacted with nucleic acids, which provided a biochemical response that is detectable in living cells.

Alyssin and Iberin in Cruciferous Vegetables Exert Anticancer Activity in HepG2 by Increasing Intracellular Reactive Oxygen Species and Tubulin Depolymerization

To determine the chemopreventive potential of alyssin and iberin, the in vitro anticancer activities and molecular targets of isothiocyanates (ITCs) were measured and compared to sulforaphane in hepatocellular carcinoma cell HepG2. The SR-FTIR spectra observed a similar pattern vis-à-vis the biomolecular alteration amongst the ITCs-treated cells suggesting a similar mode of action. All of the ITCs in this study cause cancer cell death through both apoptosis and necrosis in concentration dependent manner (20–80 μM). We found no interactions of any of the ITCs studied with DNA. Notwithstanding, all of the ITCs studied increased intracellular reactive oxygen species (ROS) and suppressed tubulin polymerization, which led to cell-cycle arrest in the S and G₂/M phase. Alyssin possessed the most potent anticancer ability; possibly due to its ability to increase intracellular ROS rather than tubulin depolymerization. Nevertheless, the structural influence of alkyl chain length on anticancer capabilities of ITCs remains inconclusive. The results of this study indicate an optional, potent ITC (viz., alyssin) because of its underlying mechanisms against hepatic cancer. As a consequence, further selection and development of effective chemotherapeutic ITCs is recommended.

In vitro FTIR microspectroscopy analysis of primary oral squamous carcinoma cells treated with cisplatin and 5-fluorouracil: a new spectroscopic approach for studying the drug-cell interaction

In the present study, human primary oral squamous carcinoma cells treated with cisplatin and 5-fluorouracil were analyzed, for the first time, by in vitro FTIR Microspectroscopy (FTIRM), to improve the knowledge on the biochemical pathways activated by these two chemotherapy drugs. To date, most of the studies regarding FTIRM cellular analysis have been executed on fixed cells from immortalized cell lines. FTIRM analysis performed on primary tumor cells under controlled hydrated conditions provides more reliable information on the biochemical processes occurring in in vivo tumor cells. This spectroscopic analysis allows to get on the same sample and at the same time an overview of the composition and structure of the most remarkable cellular components. In vitro FTIRM analysis of primary oral squamous carcinoma cells evidenced a time-dependent drug-specific cellular response, also including apoptosis triggering. Furthermore, the univariate and multivariate analyses of IR data evidenced meaningful spectroscopic differences ascribable to alterations affecting cellular proteins, lipids and nucleic acids. These findings suggest for the two drugs different pathways and extents of cellular damage, not provided by conventional cell-based assays (MTT assay and image-based cytometry).

Fourier transform infrared spectroscopy based spectral biomarkers of metastasized breast cancer progression

Breast cancer is a global health issue and the second leading cause of cancer death in women. Breast cancer tends to migrate to bone and causes bone metastases which is ultimately the cause of death. Here, we report the use of FTIR to identify spectral biomarkers of cancer progression on 3D in vitro model of breast cancer bone metastasis. Our results indicate that the following spectral biomarkers can monitor cancer progression, for example, lipids (CH2 asymmetric/CH2 symmetric stretch), Amide I/Amide II, and RNA/DNA. Principal component analysis also confirmed the involvement of protein, lipids and nucleic acids in cancer progression on sequential culture. The collective observations from this study suggest successful application of FTIR as a non-invasive and accurate method to identify biochemical changes in cancer cells during the progression of breast cancer bone metastasis.

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.

HTS-FTIR spectroscopy allows the classification of polyphenols according to their differential effects on the MDA-MB-231 breast cancer cell line

Breast cancer is a major public health issue among women in the world. Meanwhile new anticancer treatments struggle more and more to be accepted in the pharmaceutical market and research costs still increase. There is therefore a need to find new treatments and new screening methods to test them more quickly and efficiently. Among natural compounds, an increasing interest has been given to polyphenols as they can take action at the different stages of carcinogenesis, from tumour initiation to metastasis formation, by disturbing multiple cellular signalling pathways. They constitute one of the largest groups of plant metabolites and more than 8000 compounds have already been identified based on their chemical structure. Traditionally in pharmacology, new anticancer drugs are first evaluated for their potential to inhibit the proliferation of cancer cell lines. Numerous potential drugs are discarded at this stage even though they could show interesting modes of action. In turn, there is an increasing demand for more systemic approaches in order to obtain a global and accurate insight into the biochemical processes mediated by drugs. Recently, FTIR spectroscopy was demonstrated to be an innovative tool to obtain a unique fingerprint of the effects of anticancer drugs on cells in culture. While this spectral technique appears to have a definite potential to sort drugs according to their spectral fingerprints, characteristic of the metabolic modifications induced, the present challenge remains to evaluate the drug-induced spectral changes in cancer cells on a larger scale. This article presents the results obtained for a 24 h-exposure of the breast cancer cell line MDA-MB-231 to 15 compounds belonging to different classes of polyphenols using FTIR spectroscopy connected to a high throughput screening extension. Through unsupervised and supervised statistical analyses (PCA, MANOVA, Student's t-tests and HCA), a distinction between polyphenol treatments and controls could be well established.

A Plasma Biochemical Analysis of Acute Lead Poisoning in a Rat Model by Chemometrics-Based Fourier Transform Infrared Spectroscopy: An Exploratory Study

In this work, we explored to use chemometrics-based Fourier transform infrared (FTIR) spectroscopy to investigate the plasma biochemical changes due to acute lead poisoning (ALP) in a rat model. We first collected the FTIR spectra of the plasma samples from the rats with and without suffering from ALP. We then performed the chemometric analysis of these FTIR spectra using principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). We found that the chemometrics-based FTIR spectroscopy can discriminate the rats with and without ALP. Further analysis on the PLS-DA regression coefficient revealed that the spectral changes, in particular, corresponding to the biochemical changes of proteins in the plasma may be used as potential spectral biomarkers for the diagnostics of lead poisoning. Our work demonstrates the potential of chemometrics-based FTIR spectroscopy as a promising tool for the biochemical analysis of plasma that could consequently enable an objective, convenient and non-destructive diagnostics of lead poisoning. To the best of our knowledge, this work is the first application of chemometrics-based FTIR spectroscopy in the diagnostics of lead poisoning.

Protein Expression Modifications in Phage-Resistant Mutants of Aeromonas salmonicida after AS-A Phage Treatment

The occurrence of infections by pathogenic bacteria is one of the main sources of financial loss for the aquaculture industry. This problem often cannot be solved with antibiotic treatment or vaccination. Phage therapy seems to be an alternative environmentally-friendly strategy to control infections. Recognizing the cellular modifications that bacteriophage therapy may cause to the host is essential in order to confirm microbial inactivation, while understanding the mechanisms that drive the development of phage-resistant strains. The aim of this work was to detect cellular modifications that occur after phage AS-A treatment in A. salmonicida, an important fish pathogen. Phage-resistant and susceptible cells were subjected to five successive streak-plating steps and analysed with infrared spectroscopy, a fast and powerful tool for cell study. The spectral differences of both populations were investigated and compared with a phage sensitivity profile, obtained through the spot test and efficiency of plating. Changes in protein associated peaks were found, and these results were corroborated by 1-D electrophoresis of intracellular proteins analysis and by phage sensitivity profiles. Phage AS-A treatment before the first streaking-plate step clearly affected the intracellular proteins expression levels of phage-resistant clones, altering the expression of distinct proteins during the subsequent five successive streak-plating steps, making these clones recover and be phenotypically more similar to the sensitive cells.

Application of FTIR spectroscopy for traumatic axonal injury: a possible tool for estimating injury interval

Traumatic axonal injury (TAI) is a progressive and secondary injury following traumatic brain injury (TBI). Despite extensive investigations in the field of forensic science and neurology, no effective methods are available to estimate TAI interval between injury and death. In the present study, Fourier transform IR (FTIR) spectroscopy with IR microscopy was applied to collect IR spectra in the corpus callosum (CC) of rats subjected to TAI at 12, 24, and 72 h post-injury compared with control animals. The classification amongst different groups was visualized based on the acquired dataset using hierarchical cluster analysis (HCA) and partial least square (PLS). Furthermore, the established PLS models were used to predict injury interval of TAI in the unknown sample dataset. The results showed that samples at different time points post-injury were distinguishable from each other, and biochemical changes in protein, lipid, and carbohydrate contributed to the differences. Then, the established PLS models provided a satisfactory prediction of injury periods between different sample groups in the external validation. The present study demonstrated the great potential of FTIR-based PLS algorithm as an objective tool for estimating injury intervals of TAI in the field of forensic science and neurology.

Analysis of pulmonary surfactant by Fourier transform infrared spectroscopy after exposure to sevoflurane and isoflurane

Pulmonary surfactant, consisting primarily of phospholipids and four surfactant-specific proteins, is among the first structures that is exposed to inhalation anesthetics. Consequently, changes of pulmonary surfactant due to this exposure could cause respiratory complications after long anesthetic procedures. Fourier transform infrared (FTIR) spectroscopy was used to explore the effects of two inhalation anesthetics, sevoflurane and isoflurane, on a commercially available pulmonary surfactant. The research was primarily focused on the effect of anesthetics on the lipid component of the surfactant. Four different concentrations of anesthetics were added, and the doses were higher from the low clinical doses typically used. Recorded spectra were analyzed using principal component analysis, and the Student's t-test was performed to confirm the results. The exposure to both anesthetics induced similar changes, consistent with the increase of the anesthetic concentration. The most pronounced effect was on the hydrophilic head group of phospholipids, which is in agreement with the disruption of the hydrogen bond, caused by the anesthetics. A change in the band intensities of CH2 stretching vibrations, indicative of a disordering effect of anesthetics on the hydrophobic tails of phospholipids, was also observed. Changes induced by isoflurane appear to be more pronounced than those induced by sevoflurane. Furthermore, our results suggest that FTIR spectroscopy is a promising tool in studying anesthetic effects on pulmonary surfactant.

Effects of nilotinib on leukaemia cells using vibrational microspectroscopy and cell cloning

S-FTIR and Raman microspectroscopies identify spectral markers of sensitivity/resistance to nilotinib in leukaemia cell clones.

Evaluation of cytotoxic and genotoxic activity of fungicide formulation Tango® Super in bovine lymphocytes

Tango^® Super is a two-compound fungicide formulation widely employed in grain protection. However, details of Tango^® Super effects on cell cultures have not been fully investigated. In this study, bovine lymphocytes were exposed to a concentration range 0.5; 1.5; 3; 6; and 15 μg mL^-1 for 4 h to assess the cytotoxicity and genotoxicity of the fungicide. Our experiments revealed that this fungicide treatment reduced cell viability, decreased cell proliferation and provoked apoptotic cell death. Cell cycle analysis showed predominant accumulation of cells in the G₀/G₁ phase of the cell cycle. The fungicide was able to induce mitochondrial superoxide production accompanied by elevated levels of carbonylated proteins and changes in the lipid membrane composition. The fungicide did not induce micronuclei production, but stimulated both DNA double-strand breaks and the formation of p53 binding protein, which is accumulated during the DNA repair process at the site of double-strand breaks. Based on the obtained data we suppose that the fungicide-induced DNA damage is the result of oxidative stress, which may contribute to higher occurrence of apoptotic cell death. Because ergosterol biosynthesis-inhibiting fungicides are widely used in agriculture to ensure higher crop yields and may cause health impairment of animals and humans, there is a need for further testing to elucidate their potential genotoxic effects using in vivo and/or in vitro systems.

Metabolic profiling of recombinant Escherichia coli cultivations based on high-throughput FT-MIR spectroscopic analysis

Escherichia coli is one of the most used host microorganism for the production of recombinant products, such as heterologous proteins and plasmids. However, genetic, physiological and environmental factors influence the plasmid replication and cloned gene expression in a highly complex way. To control and optimize the recombinant expression system performance, it is very important to understand this complexity. Therefore, the development of rapid, highly sensitive and economic analytical methodologies, which enable the simultaneous characterization of the heterologous product synthesis and physiologic cell behavior under a variety of culture conditions, is highly desirable. For that, the metabolic profile of recombinant E. coli cultures producing the pVAX-lacZ plasmid model was analyzed by rapid, economic and high-throughput Fourier Transform Mid-Infrared (FT-MIR) spectroscopy. The main goal of the present work is to show as the simultaneous multivariate data analysis by principal component analysis (PCA) and direct spectral analysis could represent a very interesting tool to monitor E. coli culture processes and acquire relevant information according to current quality regulatory guidelines. While PCA allowed capturing the energetic metabolic state of the cell, e.g. by identifying different C-sources consumption phases, direct FT-MIR spectral analysis allowed obtaining valuable biochemical and metabolic information along the cell culture, e.g. lipids, RNA, protein synthesis and turnover metabolism. The information achieved by spectral multivariate data and direct spectral analyses complement each other and may contribute to understand the complex interrelationships between the recombinant cell metabolism and the bioprocess environment towards more economic and robust processes design according to Quality by Design framework. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:285-298, 2017.

Infrared spectroscopy detects changes in an amphibian cell line induced by fungicides: Comparison of single and mixture effects

Amphibians are regarded as sensitive sentinels of environmental pollution due to their permeable skin and complex life cycle, which usually involves reproduction and development in the aquatic environment. Fungicides are widely applied agrochemicals and have been associated with developmental defects in amphibians; thus, it is important to determine chronic effects of environmentally-relevant concentrations of such contaminants in target cells. Infrared (IR) spectroscopy has been employed to signature the biological effects of environmental contaminants through extracting key features in IR spectra with chemometric methods. Herein, the Xenopus laevis (A6) cell line was exposed to low concentrations of carbendazim (a benzimidazole fungicide) or flusilazole (a triazole fungicide) either singly or as a binary mixture. Cells were then examined using attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy coupled with multivariate analysis. Results indicate significant changes in the IR spectra of cells induced by both agents at all concentrations following single exposures, primarily in regions associated with protein and phospholipids. Distinct differences were apparent in the IR spectra of cells exposed to carbendazim and those exposed to flusilazole, suggesting different mechanisms of action. Exposure to binary mixtures of carbendazim and flusilazole also induced significant spectral alterations, again in regions associated with phospholipids and proteins, but also in regions associated with DNA and carbohydrates. Overall these findings demonstrate that IR spectroscopy is a sensitive technique for examining the effects of environmentally-relevant levels of fungicides at the cellular level. The combination of IR spectroscopy with the A6 cell line could serve as a useful model to identify agents that might threaten amphibian health in a rapid and high throughput manner.

Bladder cancer diagnosis from bladder wash by Fourier transform infrared spectroscopy as a novel test for tumor recurrence

This study proposes Fourier Transform Infrared (FTIR) spectroscopy as a more sensitive, rapid, non-destructive and operator-independent analytical diagnostic method for bladder cancer recurrence from bladder wash than other routinely used urine cytology and cystoscopy methods. A total of 136 patients were recruited. FTIR spectroscopic experiments were carried out as a blind study, the classification results of which were then compared with those of cytology and cystoscopy. Firstly, 71 samples (n = 37; bladder cancer and n = 34; control) were studied with transmittance FTIR spectroscopy. After achieving successful differentiation of the groups, to develop a more rapid diagnostic tool and check the reproducibility of the results, the work was continued with different samples (n = 65 as n = 44; bladder cancer and n = 21; control), using the reflection mode (ATR) of FTIR spectroscopy by a different operator. The results revealed significant alterations in moleculer content in the cancer group. Based on the spectral differences, using transmittance FTIR spectroscopy coupled with chemometrics, the diseased group was successfully differentiated from the control. When only carcinoma group was taken into consideration a sensitivity value of 100% was achieved. Similar results were also obtained by ATR-FTIR spectroscopy. This study shows the power of infrared spectroscopy in the diagnosis of bladder cancer.

Label-free phenotyping of peripheral blood lymphocytes by infrared imaging

It is now widely accepted that the immune microenvironment of tumors and more precisely Tumor Infiltrating Lymphocytes (TIL) play an important role in cancer development and outcome. TILs are considered to be important prognostic and predictive factors based on a growing body of clinical evidence; however, their presence at the tumor site is not currently assessed routinely. FTIR (Fourier transform infrared) imaging has proven it has value in studying a range of tumors, particularly for characterizing tumor cells. Currently, very little is known about the potential for FTIR imaging to characterize TIL. The present proof of concept study investigates the ability of FTIR imaging to identify the principal lymphocyte subpopulations present in human peripheral blood (PB). A negative cell isolation method was employed to select pure, label-free, helper T cells (CD4(+)), cytotoxic T cells (CD8(+)) and B cells (CD19(+)) from six healthy donors PB by Fluorescence Activated Cell Sorting (FACS). Cells were centrifuged onto Barium Fluoride windows and ten infrared images were recorded for each lymphocyte subpopulation from all six donors. After spectral pre-treatment, statistical analyses were performed. Unsupervised Principal Component Analyses (PCA) revealed that in the absence of donor variability, CD4(+) T cells, CD8(+) T cells and B cells each display distinct IR spectral features. Supervised Partial Least Square Discriminant Analyses (PLS-DA) demonstrated that the differences between the three lymphocyte subpopulations are reflected in their IR spectra, permitting their individual identification even when significant donor variability is present. Our results also show that a distinct spectral signature is associated with antibody binding. To our knowledge this is the first study reporting that FTIR imaging can effectively identify T and B lymphocytes and differentiate helper T cells from cytotoxic T cells. This proof of concept study demonstrates that FTIR imaging is a reliable tool for the identification of lymphocyte subpopulations and has the potential for use in characterizing TIL.

FTIR spectral signature of anticancer drugs. Can drug mode of action be identified?

Infrared spectroscopy has brought invaluable information about proteins and about the mechanism of action of enzymes. These achievements are difficult to transpose to living organisms as all biological molecules absorb in the mid infrared, with usually a high degree of overlap. Deciphering the contribution of each enzyme is therefore almost impossible. On the other hand, small changes in the infrared spectra of cells induced by environmental conditions or drugs may provide an accurate signature of the metabolic shift experienced by the cell as a response to a change in the growth medium. The present paper aims at reviewing the contribution of infrared spectroscopy to the description of small chemical changes that occur in cells when they are exposed to a drug. In particular, this review will focus on cancer cells and anti-cancer drugs. Results accumulated so far tend to demonstrate that infrared spectroscopy could be a very accurate descriptor of the mode of action of anticancer drugs. If confirmed, such a segmentation of potential drugs according to their "mode of action" will be invaluable for the discovery of new therapeutic molecules. This article is part of a Special Issue entitled: Physiological Enzymology and Protein Functions.

Vibrational spectroscopic methods for cytology and cellular research

The use of vibrational spectroscopy, FTIR and Raman, for cytology and cellular research has the potential to revolutionise the approach to cellular analysis. Vibrational spectroscopy is non-destructive, simple to operate and provides direct information. Importantly it does not require expensive exogenous labels that may affect the chemistry of the cell under analysis. In addition, the advent of spectroscopic microscopes provides the ability to image cells and acquire spectra with a subcellular resolution. This introductory review focuses on recent developments within this fast paced field and highlights potential for the future use of FTIR and Raman spectroscopy. We particularly focus on the development of live cell research and the new technologies and methodologies that have enabled this.

Chemical Analysis in the Corpus Callosum Following Traumatic Axonal Injury using Fourier Transform Infrared Microspectroscopy: A Pilot Study

Evaluating traumatic axonal injury remains challenging in clinical and forensic sciences as its identification is difficult using routine diagnostic methods. This study used Fourier transform infrared microspectroscopy to detect TAI within the corpus callosum in an animal model. Protein conformational analysis revealed significantly increased β-sheet and β-turn contents paralleled by a decrease in α-helix content at 24 h postinjury, while the antiparallel β-sheet content was decreased at 12 h postinjury. Compared with the control group, the lipid/protein ratio was significantly reduced in all of the injured groups. At 24 h postinjury, there were increases in the olefinic=CH and CH3 group of lipids accompanied by the decreased CH2 group, but the results at 12 and 72 h were contrary to that at 24 h. Our study showed that FTIRM could differentiate injured from normal white matter at different time points following TBI via examination of these infrared spectral parameters.

FTIR spectroscopy reveals lipid droplets in drug resistant laryngeal carcinoma cells through detection of increased ester vibrational bands intensity

The major obstacle to successful chemotherapy of cancer patients is drug resistance. Previously we explored the molecular mechanisms of curcumin cross-resistance in carboplatin resistant human laryngeal carcinoma 7T cells. Following curcumin treatment we found a reduction in curcumin accumulation, and reduced induction of reactive oxygen species (ROS) and their downstream effects, compared to parental HEp-2 cells. In order to shed more light on mechanisms involved in drug resistance of 7T cells, in the present study we applied Fourier transform infrared (FTIR) spectroscopy, a technique that provides information about the nature and quantities of all molecules present in the cell. By comparing the spectra from parental HEp-2 cells and their 7T subline, we found an increase in the intensity of ester vibrational bands in 7T cells. This implied an increase in the amount of cholesteryl esters in resistant cells, which we confirmed by an enzymatic assay. Since cholesteryl esters are localized in lipid droplets, we confirmed their higher quantity and serum dependency in 7T cells compared to HEp-2 cells. Moreover, treatment with oleic acid induced more lipid droplets in 7T when compared to HEp-2 cells, as shown by flow cytometry. We can conclude that along with previously determined molecular mechanisms of curcumin resistance in 7T cells, these cells exhibit an increased content of cholesteryl esters and lipid droplets, suggesting an alteration in cellular lipid metabolism as a possible additional mechanism of drug resistance. Furthermore, our results suggest the use of FTIR spectroscopy as a promising technique in drug resistance research.

Biomedical investigations using Fourier transform-infrared microspectroscopy

One of the most exciting recent developments in infrared spectroscopy has been the coupling of the spectrometer to an infrared microscope. The combination of the new infrared spectrometer and a microscope was a natural thought of scientists in these fields. This development has been so rewarding and so useful in solving today's chemical problems that infrared microspectroscopy has quickly become a significant subclassification of infrared spectroscopy. Infrared microspectroscopy has a much longer history than the recent enthusiasm would imply, however. The great interest in the use of infrared spectroscopy to solve biomedical problems that occurred in recent years shortly spread into the medical and biological fields. The aim of this review is to discuss the new developments in applications of FT-IR microspectroscopy in biomedical analysis, covering the period between 2008 and 2013.