Wyniki wyszukiwania - Biblioteka Nauki

1

The effect of pH on the interfacial tension of bilayer lipid membranes formed from phosphatidylcholine or phosphatidylserine

100%

Petelska A. D. , Naumowicz M. , Figaszewski Z. A.

Cellular and Molecular Biology Letters

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2001

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tom 06

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nr 2A

419

2

Isolation and analysis of phospholipids

100%

Ostrowska J. , Skrzydlewska E. , Figaszewski Z. A.

Chemia Analityczna

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2000

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tom Vol. 45, No. 5

613-629

EN

Different chromatographic methods used for the determination of phospholipids isolated from natural biological membranes have been described. A particular attention is given to the choice of the HPLC technique, and to the separation conditions: stationary phase, composition of mobile phase and detectors.

PL

W artykule dokonano przeglądu literatury na temat izolacji fosfolipidów z błon biologicznych. Szczególną uwagę zwrócono na wykorzystanie do tego celu techniki HPLC, na warunki rozdziału: fazy stacjonarne, skład faz ruchomych oraz detektory.

3

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

100%

Naumowicz M. , Petelska A. D. , Figaszewski Z. A.

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2003

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tom 08

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nr 1

EN

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 μF/cm2, and resistance to 1.44xl04 and 2.12x 106 Ω cm2, 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 (Γ3), capacitance (C3), and conductance (R 31), as well as the stability constant (K) of the complex. The mean values of those magnitudes are as follows: 4.265xl0-6 mol/m2, 0.54 μF/cm2, 1.381xl0-6 Ω-1 cm-2 and 3.748x107, respectively.

4

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

100%

Naumowicz M. , Petelska A. D. , Figaszewski Z. A.

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2003

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tom 08

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nr 2

EN

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.

5

Impact of the charge density of phospholipid bilayers on lubrication of articular cartilage surfaces

75%

Pawlak Z. , Kotynska J. , Figaszewski Z. A. , Oloyede A. , Gadomski A. , Gudaniec A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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tom Vol. 23, nr 1

47-50

EN

Purpose: We attempt to answer the question how some changes in acid - base equilibrium have an impact on the charge density of a phospholipid bilayer formed during lubrication occurring at articular cartilage surfaces. Design/methodology/approach: Liposomes have been used to mimic biological phospholipid membranes on articular cartilage surface where proteins are bounded, ions are transported, energy is transducted, and cellular processes are taking place. The charge density of the membrane was determined as a function of pH and electrolyte concentration from the microelectrophoretic method. Liposome membrane has been prepared as an aqueous solution of NaCl under various pH conditions. Microelectrophoresis was used to examine the local acid-base equilibrium of the electrolytes with the membrane surface, which can be considered to be an interface of phospholipids in articular cartilage. Findings: The effects of the adsorption of ions (H+, OH- ; Na+, CI-), which are present in solution upon electric charge of the liposome membrane assembled of phosphatidycholine (PC), have also been found to exhibit pH-responsive (quasi-periodic) behavior. Research limitations/implications: We hypothesized that the acid-base dissociation behavior in phospholipid bilayers of articular cartilage is a key to understanding biolubrication processes. For example, similar previous investigators found that the behavior of a multilayer made of polyisopeptide/hyaluronic acid depends on some of the surface properties such as film thickness, surface friction, surface wetness and swelling conditions. Future work should consider the adsorption of polyelectrolyte ions, e.g., the glycoprotein lubricin and hyaluronan, at the liposome membrane surface involved, assumed that besides the H+ and OH- ions, the polyelectolyte ions were also engaged. Originality/value: This liposome membrane is a model for phospholipid bilayers and will be applied for the investigation of polyelectrolyte ions, e.g. lubricin, in articular cartilage conditions. We demonstrate that knowledge on the acid-base processes on charged surface is the key to understanding phenomena occurring at interfaces in human joints lubrication, thus pointing to the biolubrication as a charged interface-controlled process.