Lipids are organic compounds widely distributed in nature and represent one of the four main classes of organic compounds of biological interest, along with carbohydrates, proteins and nucleic acids. In eukaryotes, lipids contribute to numerous cellular functions, ranging from energy storage to cell signalling [1]. Fourier Transform Infrared Spectroscopy (FT-IR) thanks to its ability to analyze cellular components at a molecular level can be particularly useful in investigating the biochemical features of the lipid content of cells and their changes induced by interaction with physicochemical external agents.
In the present work, we aim to investigate lipids extract from cells in order to compare the results obtained by using two different geometries that are usually available for the acquisition of FT-IR spectra for liquid samples [2]. In particular, for measurements in transmission geometry few microliters of lipids extracted from hepatocarcinoma cells [3, 4] and dissolved in methanol were placed on CaF2 windows and spectra were thus acquired using the microscope stage of a Perkin Elmer Spectrum One spectrometer equipped with a mercury cadmium telluride (MCT) detector. This approach allows the collection of spectra in the range from 4000 to 1000 cm−1. For measurements in Attenuated Total Reflectance (ATR) geometry, drops of lipid extracts were placed on the top of the diamond crystal of the Universal ATR accessory of the above-mentioned FT-IR spectrometer provided by a MIR TGS detector. In this case, spectra were collected in the 4000 to 650 cm−1 wavenumber region. Multiple acquisitions of spectra were carried out, and statistical criteria were applied for monitoring and comparing them. The positive and negative aspects of the two examined acquisition modes are presented and discussed.
References
[1] Muro, E.; Atilla-Gokcumen, G.E.; Eggert, U.S. Lipids in cell biology: How can we understand them better? Mol. Biol. Cell 2014, 25, 1819–1823
[2] Errico, S.; Moggio, M.; Diano, N.; Portaccio, M.; Lepore, M.; Different experimental approaches for Fourier-Trasform infrared spectroscopy applications in biology and biotechnology: A selected choice of representative results. Biotechnol Appl Biochem. 2023, 70, 937–961.
[3] Sia,D.; Villanueva,A.; Friedman, S.L.; Llovet J.M. Liver Cancer Cell of Origin, Molecular Class, and Effects
on Patient Prognosis Gastroenterology 2017, 152, 745–76
[4] Bligh, E.G.; Dyer, W.J. A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol. 1959, 37, 911–917.
