Correlation of monomer structures of tripalmitin with the spectroscopic fingerprint of polymorphs: infrared, Raman, and DFT study

Abstract

In the light of application of vibrational spectroscopy in medical diagnosis, it is necessary to have a tool to distinguish between different lipids that may be present in biochemical samples such as cells and tissues. One of the most common lipids in the human body are triglycerides. Therefore, the aim of this work was to investigate the model triglyceride, namely tripalmitin in order to find the differences between the vibrational signatures of its polymorphs and interpret them with the help of quantum-chemical computations. Although monomeric models are not sufficient to reproduce polymorphs structure, analysis of these models is very helpful in understanding of relations between the structure and changes in vibrational spectra.

Raman spectroscopy of lipids: a review

“…The high wavenumber spectral profile (region I) for saturated, solid TAGs looks very similar. The strong band at ~2882 cm −1 originating from the Fermi resonance of methylene groups dominates in this region . Additionally, two weaker bands are observed at 2846 and 2934 cm −1 that correspond to the symmetrical stretching vibrations of the C–H in CH 2 and CH 3 moieties, respectively .…”

“…Besides the considerably bigger half‐width of the bands in the liquid E isomer, there are several other differences in the spectra of OA and EA. For instance, the ratio of bands at ~2850 [symmetric ν(C–H)] to 2890 cm −1 [asymmetric ν(C–H)] is significantly smaller for EA that correlates with its higher thermodynamic stability and crystalline order in comparison with semi‐isotropic OA . Also, the relative intensity of the feature at ~3000 cm −1 related to the =C−H stretching mode is bigger for OA compared with EA.…”

“…Raman spectra of TAGs are not widespread in the literature, and works in this field mainly concern common TAGs like tripalmitin, tristearin and triolein. The vast majority of these works refers to the polymorphism of fats and sometimes to analysis of ingredients in edible oils and occurrence in pathological changes of tissue caused by disease . In this work, the Raman spectra of 17 TAGs are presented.…”

Winter Nights during Summer Time: Stress Physiological Response to Ice and the Facilitation of Freezing Cytorrhysis by Elastic Cell Wall Components in the Leaves of a Nival Species

“…The average spectrum referring to the yellow regions confirms the protein nature of these components by protein bands at, e.g., 1660 and 1007 cm −1 ( Figure 6 d, yellow spectrum), which have been assigned to the amide I and phenylalanine vibrations in proteins [ 28 ]. The extracted average spectrum of the highlighted green lipid-rich regions shows bands at 2857 and 2883, 1448, and 1306 cm −1 ( Figure 6 d, green spectrum), which can be assigned to the CH-stretching, CH-bending, and CH-wagging of triglycerides [ 29 ]. A zoom into the spongy parenchyma based on non-negative matrix factorization (NMF) analysis gives, indeed, an endmember clearly representing pectin with the marker band at 856 cm −1 and a high accumulation between the cells ( Figure 6 e,f, red).…”

Recent advances in linear and nonlinear Raman spectroscopy. Part VII

“…correlated monomer structures of tripalmitin with the spectroscopic fingerprint of polymorphs using IR, Raman, and DFT calculations. Although monomeric models are not sufficient to reproduce polymorph structure, analysis of these models is very helpful in understanding of relations between the structure and changes in vibrational spectra . Silveira and co‐workers described the identification of oxygen in dental enamel following tooth bleaching using confocal micro‐Raman spectroscopy (MRS).…”