Biophysical Characterization of Membrane Phase Transition Profiles for the Discrimination of Outer Membrane Vesicles (OMVs) From Escherichia coli Grown at Different Temperatures

Abstract

Dynamic Light Scattering (DLS), Small Angle X-ray Scattering (SAXS) and Transmission Electron Microscopy (TEM) are physical techniques widely employed to characterize the morphology and the structure of vesicles such as liposomes or human extracellular vesicles (exosomes). Bacterial extracellular vesicles are similar in size to human exosomes, although their function and membrane properties have not been elucidated in such detail as in the case of exosomes. Here, we applied the above cited techniques, in synergy with the thermodynamic characterization of the vesicles lipid membrane using a turbidimetric technique to the study of vesicles produced by Gram-negative bacteria (Outer Membrane Vesicles, OMVs) grown at different temperatures. This study demonstrated that our combined approach is useful to discriminate vesicles of different origin or coming from bacteria cultured under different experimental conditions. We envisage that in a near future the techniques employed in our work will be further implemented to discriminate complex mixtures of bacterial vesicles, thus showing great promises for biomedical or diagnostic applications.

Structural insights into fusion mechanisms of small extracellular vesicles with model plasma membranes

“…Analogous approaches have been applied to investigate similar systems. [34][35][36] The SAXS profile in the investigated q-range, analysed by a simple core multi-shell model, is consistent with an asymmetric membrane profile, reported in Fig. S1, † accounting for extended polar components.…”

Tween-20 induces the structural remodelling of single lipid vesicles

“…To establish whether the observed fluorescence signals were correlated with changes in vesicle morphology, we next performed DLS as a means to assess the hydrodynamic diameters (dH) of vesicles in the ensemble. As reported by us and others (23,24,40,41), DLS is highly sensitive to the diffusion of vesicles in solution, making it particularly attractive to quantify the particle size distribution as a function of Tween-20. In the absence of Tween-20, the diameter of freshly prepared vesicles was found to be 194 ± 2 nm with a polydispersity index of ~0.47 (Figure 2E, Figure S9).…”

Extracellular Vesicles Derived From Citrus sinensis Modulate Inflammatory Genes and Tight Junctions in a Human Model of Intestinal Epithelium

“…Citrus sinensis extracellular vesicles were isolated from the orange juice by performing several filtration, ultrafiltration, and ultracentrifugation steps by following a procedure that greatly improved the recovery of vesicles ( 27 ). In fact, starting from only 350 ml of initial orange juice, we obtained preparations of CS-EVs with a final protein concentration of 1 mg/ml.…”