Biomedical subjects

Zbigniew A Figaszewski

Publications and source records attributed to Zbigniew A Figaszewski.

13 recordsLinked to original sources

PubMed2006

Interfacial tension of the lipid membrane formed from lipid-fatty acid and lipid-amine systems.

Interfacial tension has been determined for phosphatidylcholine-stearic acid and phosphatidylcholine-stearylamine membranes. Phosphatidylcholine, stearic acid and stearylamine were used in the experimental. The interfacial tension values of the pure components are 1.62x10(-3) N/m, - 1.54x10(-2) N/m and 4.40x10(-3) N/m (hypothetical values), respectively. The 1:1 complexes were formed during formation of phosphatidylcholine-stearic acid and phosphatidylcholine-stearylamine membranes. The following parameters describing the complexes were determined: the surface concentrations of the lipid membranes formed from these complexes, A(3)(-1), the interfacial tensions of such membranes, gamma(3) and the stability constants of these complexes, K.

Amines↗

PubMed2006

The interfacial tension of the lipid membrane formed from lipid-cholesterol and lipid-lipid systems.

Interfacial tension has been determined for phosphatidylcholine-cholesterol, phosphatidylcholine-phosphatidylethanolamine, and phosphatidylethanolamine-cholesterol membranes. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cholesterol (Ch) were to be investigated, because of their presence in biological membranes. Interfacial tension values of pure components are 0.81 x 10(-3) N/m, 1.67 x 10(-3) N/m, and 2.36 x 10(-3) N/m, respectively. The 1:1 complexes were formed during formation of the PC-Ch, PC-PE, and PE-Ch lipid membranes. The following parameters describing the complexes were determined: A3(-1), the surface concentrations of the lipid membranes formed from these complexes; gamma3, the interfacial tensions of such membranes and K, the stability constants of these complexes.

Cholesterol↗

PubMed2005

Interfacial tension of phosphatidylcholine-phosphatidylserine system in bilayer lipid membrane.

The effect of pH of electrolyte solution on the interfacial tension of lipid membrane formed of phosphatidylcholine (PC, lecithin)-phosphatidylserine (PS) system was studied. In this article, three models describing the H+ and OH- ions adsorption in the bilayer lipid surface are presented. In Model I and Model II, the surface is continuous with uniformly distributed functional groups constituting the centres of H+ and OH- ions adsorption while in the other the surface is built of lipid molecules, free or with attached H+ and OH- ions. In these models contribution of the individual lipid molecule forms to interfacial tension of the bilayer were assumed to be additive. In Model III the adsorption of the H+ and OH- ions at the PC-PS bilayer surface was described in terms of the Gibbs isotherm. Theoretical equations are derived to describe this dependence in the whole pH range.

Adsorption↗

PubMed2005

Impedance analysis of lipid domains in phosphatidylcholine bilayer membranes containing ergosterol.

The effect of ergosterol on the electrochemical features of the phosphatidylcholine bilayer membrane was investigated by impedance spectroscopy. The experimental impedance values obtained in the presence of different amounts of ergosterol showed evidence of domain structures within the bilayer containing < 0.06 molar fraction of ergosterol. Based on derived mathematical equations, the surface area of phospholipid/ergosterol domain was calculated; it amounts to 262 A(2). This value is consistent, taking into consideration the presented measurements as well as ordering and condensation effects of ergosterol, with a stoichiometry of such a domain equal to 3:1. The result of the investigation is the proposal of a new and simple method for the determination of the surface area and description stoichiometry of domains formed in any two-component system.

Biophysics↗

PubMed2005

The effect of the presence of valinomycin on the interfacial tension of lecithin membrane.

The effect of the presence of valinomycin in lecithin membrane on its interfacial tension has been studied. The experiments have been carried out at various forming solution compositions and at various potassium ion concentrations in electrolyte solution. Potassium chloride was used as the electrolyte. A complex was formed between the valinomycin molecule and K+ ion. The following parameters describing the complex were determined: K, the stability constant of the valinomycin-K+ complex and B, partition coefficient. These values are equal to 3.52 x 10(5) m3 mol(-1) and 6.0, respectively.

Anti-Bacterial Agents↗

PubMed2004

The effect of interaction between K(+) ions and gramicidin D on the lecithin membrane interfacial tension.

The effect of the presence of gramicidin D in a lecithin membrane on its interfacial tension has been studied. The studies have been carried out at various forming solution compositions and at various potassium ion concentrations in the electrolyte solution. Potassium chloride was used as the electrolyte. The complex was formed between the gramicidin molecule and K(+) ion. The following parameters describing the complex were determined: the surface area occupied by GK(+) complex (A(GK(+))), the interfacial tension of the GK(+) membrane complex (gamma(GK+)), and the stability constant of the gramicidin-K(+) complex (K). These values are 156 A(2), 1.89 mN m(-1) and 0.033 m(3) mol(-1), respectively.

Binding Sites↗

PubMed2003

Acid-base equilibria at interface separating electrolyte solution and lipid bilayer formed from phosphatidylserine.

The dependence of the interfacial tension of a lipid membrane formed from phosphatidylserine on the pH of the aqueous solution has been studied. The model described the H(+) and OH(-) ions adsorption in the bilayer lipid surface has been presented in this work. We take suitable equations to describe the dependence of interfacial tension of a lipid bilayer membrane on H(+) and OH(-) ion concentrations. A theoretical equation is derived to describe this dependence in the range of pH, i.e. from 2 to 12.

Acid-Base Equilibrium↗

PubMed2003

Acid-base equilibria at interface separating electrolyte solution and lipid bilayer formed from phosphatidylcholine.

The dependence of the interfacial tension of a lipid membrane formed from phosphatidylcholine on the pH of the aqueous solution has been studied. The model describing the H(+) and OH(-) ions adsorption in the bilayer lipid surface has been presented in this work. We take suitable equations to describe the dependence of interfacial tension of a lipid bilayer membrane on H(+) and OH(-) ion concentrations. A theoretical equation is derived to describe this dependence in the whole pH range.

Acid-Base Equilibrium↗

PubMed2003

Capacitance and resistance of the bilayer lipid membrane formed of phosphatidylcholine and cholesterol.

Capacity and electric resistance of lipid membranes composed of lecithin and cholesterol were determined. The components were chosen for the study because they were present in biological membranes. Capacitance of the lecithin and cholesterol membranes amounts to 0.38 and 0.61 microF/cm(2), and resistance to 1.44(10(4)and 2.12(10(6)Omega cm(2), respectively. A 1:1 complex appears as a result of lecithin-cholesterol membrane formation. Parameters of the membrane formed of the lecithin-cholesterol complex were determined: surface concentration (Gamma(3)), capacitance (C(3)), and conductance (R;(3)(-1), as well as the stability constant (K) of the complex. The mean values of those magnitudes are as follows: 4.265(10(-6)mol/m(2), 0.54 microF/cm(2), 1.381(10(-6)Omega(-1)cm(-2)and 3.748(10(7), respectively.

Cholesterol↗

PubMed2003

The effect of the presence of crown ether on ion transport across the lipid bilayer.

We studied the electric properties of phosphatidylcholine bilayers modified with crown ether (dibenzo[18] crown-6). The studies were carried out for various crown ether concentrations in forming solutions and various potassium ion concentrations in electrolyte solutions. The presence of crown ether in the membrane influences the membrane's impedance; there is a reduction in its resistivity, a decrease in its resistance of phase transfer and an increase in its capacity of phase transfer with an increase in crown ether concentration in the bilayer and in K(+) ion concentration in the electrolyte solution.

Crown Ethers↗

PubMed2002

Interfacial tension of bilayer lipid membrane formed from phosphatidylethanolamine.

The dependence of the interfacial tension of a lipid membrane on the pH of the aqueous solution has been studied. Interfacial tension measurements of phosphatidylethanolamine (PE) were carried out. A theoretical equation is derived to describe this dependence in the whole pH range. A maximum corresponding to the isoelectric point appears both in the theoretical equation and in the experimental data.

Lipid Bilayers↗

PubMed2002

Effect of pH on the interfacial tension of bilayer lipid membrane formed from phosphatidylcholine or phosphatidylserine.

The effect of pH of an electrolyte solution on the interfacial tension of lipid membrane formed from phosphatidylcholine (PC) or phosphatidylserine (PS) was studied. The relationships were well described by an equation presented earlier based on the Gibbs isotherm but only in the proximity of the isoelectric point. Therefore, in this work models have been derived to describe the adsorption of the H(+) and OH(-) ions at lipid surfaces formed from PC or PS, which would reproduce changes in interfacial tension more correctly, particularly in the ranges distant from the isoelectric point. In one model, the surface is continuous with uniformly distributed functional groups constituting the centres of H(+) and OH(-) ion adsorption while in the other the surface is built of lipid molecules, free or with attached H(+) and OH(-) ions. In both models, the contributions of the individual lipid molecule forms to the interfacial tension of the bilayer were assumed to be additive.

Hydrogen-Ion Concentration↗

PubMed2002

Interfacial tension of phosphatidylcholine-cholesterol system in monolayers at the air/water interface.

Interfacial tension of an egg lecithin-cholesterol system was measured across the whole concentration range. Surface pressure-area isotherm measurements were carried out in a Langmuir trough at the air/water interface at room temperature (22 degrees C). The interfacial tension of the air/water interface was divided into contributions of components. The interfacial tension of a 1:1 complex between phosphatidylcholine and cholesterol was calculated. Its value equals 18 mN/m. The difference between the stability constant of 1:1 complex in the bilayer and the monolayer at the air/water interface is discussed.

Algorithms↗