Correlation between spectroscopic and stoichiometric protein to lipid ratios in erythrocyte-derived extracellular vesicles and nanoerythrosomes

The erythrocyte-derived extracellular vesicles and nanoerythrosomes show high similarities due to their same origins supporting their prosperous applicability for new generations of nanocarrier systems. By the addition of a representant erythrocyte-membrane lipid which is the saturated dipalmitoyl-phosphocholine (DPPC), different morphological and structural changes occurred in function of the increasing DPPC ratio. The integration of guest DPPC molecules, expressed in weight ratio extending to an order of magnitude, yields the formation of standalone nanoerythrosomes (NERYs), while the integration of DPPC molecules is significantly reduced into red blood cell derived extracellular vesicles (RBCEVs) causing aggregations of these EVs. Despite the induced severe and different changes in morphological and structural characteristics, both systems show systematic changes in spectroscopical signals displaying quasi proportional alterations in their spectroscopical protein to lipid ratios. Sample series with controlled different amount of added lipid (DPPC) provide the observance of the correlation between spectroscopic and stoichiometric protein to lipid ratios. Independently from the selected spectroscopic lipid-determination (regarding to carbon-hydrogen and carbonyl vibrations), a linear relationship was observed between the spectroscopic and stoichiometric ratios in both erythrocyte systems (NERYs, RBCEVs) and the determination of an approximative lipid concentration comes to be possible without any lipid analytic.