Comparison between high definition FT‐IR, Raman and AFM‐IR for subcellular chemical imaging of cholesteryl esters in prostate cancer cells

Abstract

The family of vibrational spectroscopic imaging techniques grows every few years and there is a need to compare and contrast new modalities with the better understood ones, especially in the case of demanding biological samples. Three vibrational spectroscopy techniques (high definition Fouriertransform infrared [FT-IR], Raman and atomic force microscopy infrared [AFM-IR]) were applied for subcellular chemical imaging of cholesteryl esters in PC-3 prostate cancer cells. The techniques were compared and contrasted in terms of image quality, spectral pattern and chemical information. All tested techniques were found to be useful in chemical imaging of cholesterol derivatives in cancer cells. The results obtained from FT-IR and Raman imaging showed to be comparable, whereas those achieved from AFM-IR study exhibited higher spectral heterogeneity. It confirms AFM-IR method as a powerful tool in local chemical imaging of cells at the nanoscale level. Furthermore, due to polarization effect, ppolarized AFM-IR spectra showed strong enhancement of lipid bands when compared to FT-IR.atomic force microscopy, cholesteryl esters, infrared, prostate cancer, Raman, subcellular imaging

Probing amyloid fibril secondary structures by infrared nanospectroscopy: experimental and theoretical considerations

“…For the first time, a complete study of three different amyloid fibrils (Aβ, α-syn and PrP) was performed using polarized resolved AFM-IR in different illumination configurations and using two types of AFM probes. Several other polarizedresolved AFM-IR studies, 41,[47][48][49][50][51][52][53][54][55] were performed using either the bottom-up or top-down illumination configuration, but none of them has discussed in detail the effect of these different illumination and tip's gold-coating.…”

Analysis of Fixed and Live Single Cells Using Optical Photothermal Infrared with Concomitant Raman Spectroscopy

“…Despite comparing multiple vibrational spectroscopy techniques, the different resolution and pixel size often make it impossible to obtain comparable chemical information from the same area of the sample by these methods. 79 Here, we are able to:…”

“…Previous studies have focused on the comparison between IR and Raman data obtained from biological samples. Despite comparing multiple vibrational spectroscopy techniques, the different resolution and pixel size often make it impossible to obtain comparable chemical information from the same area of the sample by these methods . Here, we are able to: Identify organelles in fixed cells and live cells using both O-PTIR and Raman; Observe an increase in β-sheets or RNA bands, consistent with the nucleolus, which is the site where new ribosomes are assembled; therefore, it contains rRNA (essential component of the ribosomes) and proteins; Identify lipid-rich regions assigned to the ER from consideration of their localization in the cell (compared to our confocal fluorescence microscopy data) and the OPO IR image; Obtain, from the live cells in aqueous buffer, high-quality discrete frequency images (Figures A,B and A,B) despite the presence of the water layer, enabling the identification of lipid droplets ∼1 μm or less. …”

Rapid diagnosis of COVID-19 using FT-IR ATR spectroscopy and machine learning

“…In 2019, the use of this technique was reported in the screening of patients with brain cancer, achieving sensitivity of 93.2% and specificity of 92.8% in the identification of high-risk patients indicated for definitive diagnostic tests (more expensive), thus saving time and cost 28 . Moreover, vibrational spectroscopy has been used with very good results in different areas of health science, as brain cancer 28 , oral cancer 29 – 31 and prostate cancer 32 . In infectious diseases, a similar study was done to discriminate patients with Human immunodeficiency virus (HIV) infection by ATR-FTIR also associated with linear discriminant analysis (LDA) in plasma samples.…”