Structural sensitivity of CH vibrational band in methyl benzoate

Standard operating procedure to reveal prostate cancer specific volatile organic molecules by infrared spectroscopy

The growing number of prostate cancer cases is a real concern in modern society. Over 1.4 million new cases and about 400 thousand (>26%) deaths were registered worldwide in 2020 due to prostate cancer. The high mortality rate of prostate cancer is due to the lack of reliable early detection of the disease. Till now the most reliable diagnosis of cancer is tissue biopsy, which is an invasive process. A non-invasive or minimally invasive technique could lead to a diagnostic tool that will allow for saving or prolonging the lifespan of millions of lives. Metabolite-based diagnostics may have a better chance of early cancer detection. However, reliable detection techniques need to be developed. Infrared spectroscopy based gaseous-biofluid holds great promise towards the development of non-invasive diagnostics. A pilot study based on breath analysis by infrared spectroscopy showed promising results in distinguishing prostate cancer patients from healthy volunteers. Details of the spectral metabolic analysis are presented.

Non-Invasive Disease Specific Biomarker Detection Using Infrared Spectroscopy: A Review

Many life-threatening diseases remain obscure in their early disease stages. Symptoms appear only at the advanced stage when the survival rate is poor. A non-invasive diagnostic tool may be able to identify disease even at the asymptotic stage and save lives. Volatile metabolites-based diagnostics hold a lot of promise to fulfil this demand. Many experimental techniques are being developed to establish a reliable non-invasive diagnostic tool; however, none of them are yet able to fulfil clinicians' demands. Infrared spectroscopy-based gaseous biofluid analysis demonstrated promising results to fulfil clinicians' expectations. The recent development of the standard operating procedure (SOP), sample measurement, and data analysis techniques for infrared spectroscopy are summarized in this review article. It has also outlined the applicability of infrared spectroscopy to identify the specific biomarkers for diseases such as diabetes, acute gastritis caused by bacterial infection, cerebral palsy, and prostate cancer.

Two-dimensional Infrared Spectroscopy Reveals Better Insights of Structure and Dynamics of Protein

Proteins play an important role in biological and biochemical processes taking place in the living system. To uncover these fundamental processes of the living system, it is an absolutely necessary task to understand the structure and dynamics of the protein. Vibrational spectroscopy is an established tool to explore protein structure and dynamics. In particular, two-dimensional infrared (2DIR) spectroscopy has already proven its versatility to explore the protein structure and its ultrafast dynamics, and it has essentially unprecedented time resolutions to observe the vibrational dynamics of the protein. Providing several examples from our theoretical and experimental efforts, it is established here that two-dimensional vibrational spectroscopy provides exceptionally more information than one-dimensional vibrational spectroscopy. The structural information of the protein is encoded in the position, shape, and strength of the peak in 2DIR spectra. The time evolution of the 2DIR spectra allows for the visualisation of molecular motions.

Theory helps experiment to reveal VOCs in human breath

Volatile organic compounds (VOCs) present in human breath not only provide information about the internal chemistry of the body but can also be specific to diseases. Therefore, detection and analysis of specific VOCs can be used for medical diagnostics. However, up until today in spite of several existing VOC-based detection techniques and significant efforts, breath analysis is not a diagnostic method available for clinicians. Infrared absorption spectroscopy is a promising technique to fill this gap, with tens of identified VOCs in breath. Currently, a lack of digital spectral databases and several masking effects make difficult reliable molecular identification of observed absorption features. We demonstrate that calculations of rotational bands of vibrational spectra could serve as a basic method for molecular identification of spectral features observed in experiment. Results of comparison of several known VOCs spectra with the predictions of the theoretical model are presented.

Towards a standard operating procedure for revealing hidden volatile organic compounds in breath: the Fourier-transform IR spectroscopy case

Human breath contains a large amount of small volatile organic compounds (VOCs) and could therefore be used as a carrier of metabolic information for medical diagnostics. Still, in spite of several promising techniques that have been applied during the last decades to study breath content, there is a lack of breath-based diagnostic tools available for physicians. Among several promising techniques, infrared (IR) spectroscopy has already proved its potential for reliable detection of VOCs in the breath. However, due to the large dynamic range of molecular concentrations and overlapping absorption spectra of different VOCs, many low-absorption molecules stay hidden in spectroscopic measurements. To overcome this obstacle, we propose the Matryoshka method for removing masking effects and revealing the buried spectral structures in any bio-fluid in the gas phase. By exploiting both physical and digital removal steps, we demonstrate how the method reveals methane, acetone, aldehyde, and methyl butyrate in a real breath.

Molecular identification of bio-fluids in gas phase using infrared spectroscopy

Bio-fluids are the source of a large number of metabolites. Identification and quantification of them can be an efficient step for understanding the internal chemistry of the body as well as for developing objective diagnostics of diseases. Several techniques have been developed so far; however, their metabolite identification and/or quantification are not reliable enough for acceptance by clinicians. As another promising step in this direction, we push infrared spectroscopy of bio-fluids in gas phase. Here we discuss features of breath and urine headspace realized with Fourier transform infrared spectroscopy. Molecular identification procedures based on component analysis of gas samples are proposed. In this paper, we show that aggregate data from different bio-fluids in gas phase can strengthen the diagnostics of the body state and disease.

Ultrafast vibrational coupling between C H and C O band of cyclic amide 2-Pyrrolidinone revealed by 2DIR spectroscopy

Coupling between C H and C O vibrational modes play an essential role on determination of biological structure and dynamics. However, due to the weakness of the C H absorption and strong absorption of the C O vibrational band make such experiments less straightforward than those with transitions of nearly the same strength. In this communication the characteristics of the C H and C O coupling has been studied using dual frequency two dimensional infrared spectroscopy. 2-Pyrrolidinone has been used as a model molecule of biological system. The coherent and incoherent couplings between C H and C O vibrational bands have been observed. The cross peaks dynamics have been discussed and time constant of the cross peak intensity has been calculated.