IR and Raman spectra modeling for pathogenic bacteria cell-wall components using DFT

Recently, optical methods have become one of the main tools for biomedical applications and have made significant progress in the field of clinical evaluation [1]. A number of natural tissues were studied using spectroscopic methods, including Raman spectroscopy [2, 3]. These vibrational spectroscopy methods are relatively simple, reproducible, do not destroy tissue, and require only small amounts of material (from micrograms to nanograms) with minimal sample preparation. In addition, these methods provide information at the molecular level, allowing the study of functional groups, bond types, and molecular conformations. Spectral bands in vibrational spectra depend on the molecule and provide direct information about the biochemical composition. These bands are relatively narrow, easily resolvable, and sensitive to molecular structure, conformation, and environment. A necessary part of the practical study of any sample is the theoretical prediction of the result in order to better understand the structure of the analyte. This part of the analysis is necessary for a more accurate selection of shooting parameters and a visual representation of the expected result. One of such prediction methods is mathematical modeling. This paper presents the results of studies of SERS spectroscopy of strains of mycobacterium tuberculosis strains and their comparison with theoretical Raman spectra of organic compounds, which were chosen as amino acids (L-histidine), tripedtide (glutathione), and carboxylic acid (citric acid).