FTIR, Raman and AFM characterization of the clinically valid biochemical parameters of the thrombi in acute ischemic stroke

Abstract

The significance and utility of innovative imaging techniques in arterial clot analysis, which enable far more detailed and automated analysis compared to standard methods, are presented. The examination of two types of human thrombi is shown, representing the main ischemic stroke etiologies: fibrin–predominant clot of large vessel origin and red blood cells–rich clot of cardioembolic origin. The synergy effect of Fourier–transform infrared spectroscopy (FTIR), Raman spectroscopy (RS) and atomic force microscopy (AFM) techniques supported by chemometrics in comparison with reference histological staining was presented. The main advantage of such approach refers to free–label and non–destructive quantitative imaging of clinically valid, biochemical parameters in whole sample (FTIR–low resolution) and selected regions (RS–ultra–high resolution). We may include here analysis of lipid content, its distribution and total degree of unsaturation as well as analysis of protein content (mainly fibrin and hemoproteins). The AFM studies enhanced the vibrational data, showed clearly shape and thickness of clot features as well as visualized the fibrin framework. The extraordinary sensitivity of FTIR and RS imaging toward detection and discrimination of clinically valid parameters in clot confirms its applicability in assessment of thrombi origin.

Exosomes isolated from two different cell lines using three different isolation techniques show variation in physical and molecular characteristics

“…ATR-FTIR provided spectra without the problem of light scattering and background noise or fluorescence. In case of ATR-FTIR, the absorption of water molecules was subtracted from the background 58,59 . The techniques have been employed in recent studies to identify the molecular components of exosomes in a label free manner, differentiating them in disease versus non diseased state and discriminating the exosomes from other vesicles.…”

Lipid Droplet Composition Varies Based on Medaka Fish Eggs Development as Revealed by NIR-, MIR-, and Raman Imaging

“…However, a detailed analysis of mean Raman and IR spectra MIR spectra also identify lipids. The lipid-rich class with the minor contribution of proteins separated in UHCA analysis was defined based on several features of the mean spectrum (green trace in MIR spectra in Figure 7); bands at 2925 and 2855 cm −1 assigned to the antisymmetric and symmetric stretching vibrations of the CH 2 groups (biomolecules containing long acyl chains) and a band at 1744 cm −1 (the stretching mode of the C=O group) attributed to cholesteryl esters and triglycerides [31,32]. Moreover, a week band at 3013 cm −1 originating from the C=H stretching vibrations of the olefinic groups and a band at 1240 cm −1 of the antisymmetric stretching vibrations of PO 2 − groups clearly indicated the presence of unsaturated lipids and phospholipids in the lipid fraction [33].…”

Tauroursodeoxycholic Acid (TUDCA)—Lipid Interactions and Antioxidant Properties of TUDCA Studied in Model of Photoreceptor Membranes

“…After extracting DRM and DSM fractions from our raft-forming mixtures (see p. 2,7) we performed the analysis of TUDCA distribution between these fractions using Raman spectroscopy. RS is a technique widely used in lipids studies which is applied not only to analysis of lipid standards [ 76 ] but also for analysis of lipid fractions in cells [ 77 , 78 , 79 , 80 ] and tissues [ 81 , 82 ] including the semiquantitative approach. Figure 5 presents the comparison of the Raman spectrum of TUDCA standard compound (red) and the average Raman spectra of DSM (blue) and DRM (green) with the spectra standard deviation presented as shadow.…”

“…The analysis of the Raman spectrum of DRM suggests that the sample contains mainly saturated lipids including sphingomyelin (SM) and cholesterol groups. As previously reported, the RS technique can easily provide the information about the general lipid unsaturation level, for example, based on the RS intensity ratio of the bands located at around 1266/1300 cm −1 [ 81 ]. In the case of the Raman spectrum of DRM the band at around 1266 cm –1 [ 81 ], which is originated from the bending vibration of =CH group, is almost invisible, which indicates the minority of unsaturated lipids in this sample.…”