Abstract
Interactions between components of model lipid membranes (spherical lipid bilayers and liposomes) are investigated here. Parameters characterizing equilibria in the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-diosgenin (Dio) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-diosgenin acetate (DAc) membrane systems have been determined. The interfacial tension measurement of spherical lipid bilayers was based on the Young-Laplace’s equation using a homemade computer-controlled device. We assume a 1:1 complex in the DPPC-Dio and DPPC-DAc membrane systems. The parameters A 3 − 1 , the surface concentration of lipid membranes formed from these complexes, γ 3 , the interfacial tension of such membranes, and, K, the constant stability of these complexes were calculated. Microelectrophoresis was used for examinations of the surface charge density of lipid membranes. The values were obtained here from electrophoretic mobility data applying Smoluchowsky’s equation. The effect of pH (pH ranged of 2 to 10) on the electrolyte solution and the compositions of the membranes was analyzed. The obtained results indicate that the modification of DPPC membranes with both Dio and DAc causes changes in surface charge density values and shifts of the isoelectric point.
Highlights
Biological membranes are necessary for living organisms because they provide a selective barrier of permeability, as well an environment for many processes occurring there [1]
We have considered the case when the components of the lipid bilayer of a two-component membrane, e.g., DPPC and diosgenin or diosgenin acetate, do not form chemical compounds, where the interactions between the membrane components can be described [30,41]: γ1 m1 A1 + γ2 m2 A2 = γ m1
In the course of the interfacial tension measurements, the obtained good compliance between theoretical and experimental data verified the assumption of a 1:1 complex in the lipid bilayer
Summary
Biological membranes are necessary for living organisms because they provide a selective barrier of permeability, as well an environment for many processes occurring there [1]. These membranes are usually described as lipid bilayers, associated with proteins and other components, e.g., polysaccharides [2]. Saponins belong to a group of biological active compounds. They are natural compounds that are present in many plants of various species [11]. One of them is the active property of lowering surface tension and foaming properties, as evidenced by the amphipathic nature of these substances They are used in the Coatings 2020, 10, 368; doi:10.3390/coatings10040368 www.mdpi.com/journal/coatings
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