Browsing by Subject "EV"

Extracellular vesicles (EVs) are nano-sized lipid bilayer-delimited particles, released by cells. They take part in intercellular communication by their molecular composition and are part of both physiological and pathophysiological functions. EVs can be extracted from bodily fluids, and they are particularly abundant in blood. The purpose of this thesis was to evaluate the use of Raman spectroscopy in the characterization of EVs. Raman spectroscopy is an analysis method based on the interaction of light and matter, and the inelastic scattering of light, and it is used to get information on the biochemical composition of a substance. Principal component analysis (PCA) was used to investigate if Raman spectroscopy could differentiate two different platelet-derived EV samples, a red blood cell-derived EV-sample and a red blood cell-derived reference material. Evaluation of the characterization also included a stability study of these samples, where it was examined if any temperature dependent changes occurred that could be detected by Raman spectroscopy. Additionally, the applicability of Raman spectroscopy for lipoprotein contamination detection was evaluated by examining if purification of an EV sample decreased the intensity of carotenoid peaks typical for lipoprotein spectra. Raman spectroscopy was able to differentiate all three EV samples and the red blood cell-derived reference material from each other. The most clear differences were found between red blood cell and platelet-derived samples, due to for example the characteristic haemoglobin peaks of red blood cell-derived samples. Differences were also found between the two platelet EV samples, which were thought to implicate difference in protein compositions. The characterization of red blood cell-derived samples proved to be difficult because haemoglobin contained in the samples covered most of the other signal from the samples. Stability studies implicated that during fridge storage the carotenoid peak intensity of platelet-derived EV samples decreases due to the degradation of carotenoids. In the red blood cell-derived samples, no differences assignable to changes in some specific components of the samples were observed. Contamination studies suggested the intensity of the carotenoid peaks may increase due to purification of the sample. This was counter to the assumption and may suggest the carotenoids of the EV samples are not from lipoprotein contamination, but part of the EV composition. In conclusion, Raman spectroscopy proved to be a promising method for characterization and identification of different EV samples.