Intermediate aggregates resulting in the interaction of bile salt with liposomes studied by transmission electron microscopy and light scattering techniques

Abstract

SummaryThe interaction of sodium cholate (SC) with phosphatidylcholine liposomes was studied by means of transmission electron microscopy (TEM), changes in the mean particle size (quasielastic light scattering, QELS) and in the static light scattering (SLS) of the system during liposome solubilization. A good correlation was found between the TEM diameter of particles and the mean hydrodynamic diameter (HD) determined by QELS. The intermediate aggregates resulting in this interaction were dependent on the SC concentration in the system. Thus, an initial vesicle growth occurred when the SC concentration in the system was 13 . 79 mol%. Additional SC amounts (41 . 17 mol% SC) led to the formation of the largest vesicles (HD 410 nm). Increasing SC amounts led to a slight fall in the vesicle diameter and in the SLS of the system. Thus, for 47 . 08 mol% SC, TEM images still showed the presence of vesicles albeit with traces of smaller structures and signs of vesicle fusion. When SC concentration exceeded 48 mol% an abrupt decrease in SLS occurred, the size curve starting to show a bimodal distribution. Thus, for 50 mol% SC a sharp distribution curve appeared at 52 nm indicating the formation of small particles and TEM images showed clear signs of vesicle disintegration with formation of tubular structures. The subsequent self organization of these tubular structures (54 mol% SC) led to the formation of open multilayered structures in coexistence with small particles. A gradual increase in the number of these small particles (mixed micelles) led to the complete solubilization of liposomes.

Antioxidant Activities of Vitamins E and C in a Novel Liposome System

“…It has been previously demonstrated that the TEM technique applied to negatively stained vesicles is an appropriate method to study the formation and morphology of vesicular structure (Delamaza et al. 1997; van Zanten and Zasadzinski 2005).…”

“…It has been previously demonstrated that the TEM technique applied to negatively stained vesicles is an appropriate method to study the formation and morphology of vesicular structure (Delamaza et al 1997;van Zanten and Zasadzinski 2005). Microstructures of the vesicle are readily visualizable owing to their high electron density, but negative staining with uranyl acetate is performed to enhance image quality.…”

LipoBots: Using Liposomal Vesicles as Protective Shell of Urease‐Based Nanomotors

“…Moreover, a comparison of LB-I incubated in PBS containing urea in the presence and absence of sodium deoxycholate showed that liposomes were more elongated in presence of sodium deoxycholate, further suggesting a higher flexibility (and thus, permeability) of LB-I under these conditions, as reported in literature. [55] The possibility to fabricate enzyme-encapsulated nanomotors which motion is activated under certain conditions opens new avenues for using this class of nanomotors in conditions in which the enzymes can degrade. As proof-of-concept, we evaluated whether the liposomal chassis can be used to protect the enzymes when crossing adverse conditions, making them still active when the motion triggering conditions are found or applied.…”

“…For comparison purposes, we also synthesized a second prototype of LBs, LipoBots-Outside (LB-O), in which the urease enzymes are attached to the liposomes' surface by physisorption. [54] This salt acts as an edge activator, causing disruption and permeabilization of the lipid bilayer [55][56][57] and therefore, enabling exchange of substrates and products. Accordingly, exposure of LB-I to sodium deoxycholate triggers motion of the nanomotor.…”

Interaction of alkyltrimethylammonium bromides with DMPC-d54 and DMPG-d54 monolayers studied by infrared reflection absorption spectroscopy (IRRAS)

“…calorimetry [20][21][22][23][24], neutron scattering [25][26][27], X-ray diffraction [28], spectroscopy [29,30]; and several other biophysical techniques. The determination of partition coefficients of amphiphilic molecules for partitioning between aqueous and lipid phase is of fundamental importance for a quantitative interpretation of lipid-surfactant interactions and provides the basis for the understanding of the intermolecular interaction energies.…”