Physicochemical and electrical properties of DPPC bilayer membranes in the presence of oleanolic or asiatic acid.

This study aimed to investigate the effect of selected compounds from the group of triterpene sapogenins on model phosphatidylcholine membranes. Two types of biological membrane model systems were used in the work, i.e.

Lithocholic acid-based oligomers as drug delivery candidates targeting model of lipid raft.

This study presents a new approach to designing a lithocholic acid functionalized oligomer (OLithocholicAA-X) that can be used as a drug carrier with additional, beneficial activity. Namely, this novel oligomer can incorporate an anti-cancer drug due to the application of an effective backbone as its component (lithocholic acid) alone is known to have anticancer activity. The oligomer was synthesized and characterized in detail by nuclear magnetic resonance, attenuated total reflectance Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, thermal analysis, and mass spectrometry analysis.

The Equilibria of Triterpene Sapogenins-Phosphatidylcholine in Monolayers at the Air/Water Interface.

Sapogenins are the non-sugar parts of saponins (aglycones), high-molecular-weight glycosides linked to one or more sugar side chains. This group of compounds presents many properties, e.g.

Site of the Hydroxyl Group Determines the Surface Behavior of Bipolar Chain-Oxidized Cholesterol Derivatives─Langmuir Monolayer Studies Supplemented with Theoretical Calculations.

Cholesterol oxidation products (called oxysterols) are involved in many biological processes, showing both negative (e.g., neurodegenerative) and positive (e.

The Effect of Selected Flavonoids and Lipoic Acid on Natural and Model Cell Membranes: Langmuir and Microelectrophoretic Methods.

The influence of kaempferol (K), myricetin (M) and lipoic acid (LA) on the properties of natural erythrocytes, isolated from animal blood and biological membrane models (monolayers and liposomes) made of phosphatidylcholine (PC), cholesterol (CHOL), and sphingomyelin (SM), CHOL in a ratio of 10:9, was investigated. The Langmuir method, Brewster angle microscopy (BAM) and microelectrophoresis were used. The presented results showed that modification of liposomes with kaempferol, myricetin and lipoic acid caused changes in the surface charge density and the isoelectric point value.

Study of Nano h-BN Impact on Lubricating Properties of Selected Oil Mixtures.

Our experiments aimed to study the influence of layered materials with nanometric-scale particles, which are part of lubricant oils, on their tribological properties. The object of this study was a lubricant oil made using base oil PAO4, which contained nanoparticle hexagonal boron nitride (nano h-BN) and a dispersant based on succinic acid imide. Comparative tests for engine oil (CB30) were also performed.

25-hydroxycholesterol interacts differently with lipids of the inner and outer membrane leaflet - The Langmuir monolayer study complemented with theoretical calculations.

25-hydroxycholesterol (25-OH), a molecule with unusual behavior at the air/water interface, being anchored to the water surface alternatively with a hydroxyl group at C(3) or C(25), has been investigated in mixtures with main membrane phospholipids (phosphatidylcholines - PCs, and phosphatidylethanolamines - PEs), characteristic of the outer and inner membrane leaflet, respectively. To achieve this goal, the classical Langmuir monolayer approach based on thermodynamic analysis of interactions was conducted in addition to microscopic imaging of films (in situ with BAM and after transfer onto mica with AFM), surface-sensitive spectroscopy (PM-IRRAS), as well as theoretical calculations. Our results show that the strength of interactions is primarily determined by the kind of polar group (strong, attractive interactions leading to surface complexes formation were found to occur with PCs while weak or repulsive ones with PEs).

Interactions between Phosphatidylcholine and Kaempferol or Myristicin: Langmuir Monolayers and Microelectrophoretic Studies.

Flavonoid compounds are known for their antibacterial, anti-inflammatory, and anticancer properties. Therefore, they can influence membrane properties that interest us, modifying both their structure and functions. We used kaempferol (K) and myricetin (M) as representatives of this group.

Experimental and Theoretical Approaches to Describing Interactions in Natural Cell Membranes Occurring as a Result of Fatal Alcohol Poisoning.

We propose herein a theoretical model describing the effect of fatal ethanol poisoning on the equilibria between cell membranes and the surrounding ions. Using this model, we determined the parameters characterizing the interaction between the electrolyte solution's ions and the functional groups on the blood cells' surface. Via the application of mathematical equations, we calculated the total surface concentrations of the acidic and basic groups, and , and their association constants with solution ions, and .

How the replacement of cholesterol by 25-hydroxycholesterol affects the interactions with sphingolipids: The Langmuir Monolayer Study complemented with theoretical calculations.

In this paper, a representative of chain-oxidized sterols, 25-hydroxycholesterol (25-OH), has been studied in Langmuir monolayers mixed with the sphingolipids sphingomyelin (SM) and ganglioside (GM) to build lipid rafts. A classical Langmuir monolayer approach based on thermodynamic analysis of interactions was complemented with microscopic visualization of films (Brewster angle microscopy), surface-sensitive spectroscopy (polarization modulation-infrared reflection-absorption spectroscopy) and theoretical calculations (density functional theory modelling and molecular dynamics simulations). Strong interactions between 25-OH and both investigated sphingolipids enabled the formation of surface complexes.

Interactions between Beta-2-Glycoprotein-1 and Phospholipid Bilayer-A Molecular Dynamic Study.

This study aims to investigate the interactions appearing when the beta-2-glycoprotein-1 binds to a lipid bilayer. The inter- and intra-molecular forces acting between the two macromolecular systems have been investigated using a molecular dynamics simulation method. The importance of water bridges has also been addressed.

Research on the Influence of the Manufacturing Process Conditions of Iron Sintered with the Addition of Layered Lubricating Materials on its Selected Properties.

The purpose of the conducted experiments was to test the selected properties of materials intended for porous sintered bearings containing layered materials in the form of powders with an average particle size of 0.5-1.5 μm, with very good tribological properties.

The Equilibria in Lipid-Lipoic Acid Systems: Monolayers, Microelectrophoretic and Interfacial Tension Studies.

In this examination, we investigated the effect of lipoic acid (LA) on the properties of biological membrane models (monolayers, bilayers, and liposomes) formed from phosphatidylcholine (PC) or phosphatidylserine (PS) using the Langmuir, microelectrophoresis, and interfacial tension methods. The Langmuir technique allowed us to calculate the π-A isotherms and determine the molecular surface areas of pure and mixed monolayers. Using mathematical equations, we established that LA and the lipids formed complexes at a 1:1 ratio.

Unusual Behavior of the Bipolar Molecule 25-Hydroxycholesterol at the Air/Water Interface-Langmuir Monolayer Approach Complemented with Theoretical Calculations.

In this study, 25-hydroxycholesterol (25-OH), a biamphiphilic compound with a wide range of biological activities, has been investigated at the air/water interface. We were interested in how two hydroxyl groups attached at distal positions of the 25-OH molecule (namely, at C(3) in the sterane system and at C(25) in the side chain) influence its surface behavior. Apart from traditional Langmuir monolayers, other complementary surface-sensitive techniques, such as electric surface potential measurements, Brewster angle microscopy (BAM, enabling texture visualization and film thickness measurements), and polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS), were applied.

Thermodynamic, viscoelastic and electrical properties of lipid membranes in the presence of astaxanthin.

Among numerous compounds found in marine organisms, astaxathin has received considerable research interest due to beneficial impact on health such as anti-inflammatory, antioxidant and neuroprotective activity. Recently new functionalities of this xanthophyll have been revealed indicating important applications in nutrition and pharmacy. However, astaxanthin, as the bioactive, has limited value without a protecting carrier that provides controlled release in a human body.

Influence of Manufacturing Technology on the Structure of 80W-20Re Heavy Sinters.

Preliminary measurement results of 80W-20Re heavy sinters are presented in this paper. Tested samples were taken from three different technology processes, i.e.

The Amphoteric and Hydrophilic Properties of Cartilage Surface in Mammalian Joints: Interfacial Tension and Molecular Dynamics Simulation Studies.

In this paper, we explain the amphoteric character of the cartilage surface by studying a lipid bilayer model built from phospholipids. We examined the interfacial tension values and molecular dynamics simulation in solutions of varying pH. The effects of negative and positive charge density (or fixed charges) on the (cartilage/cartilage) friction coefficient were investigated.

Complex formation equilibria between cholesterol and diosgenin analogues in monolayers determined by the Langmuir method.

The purpose of this study was to investigate the interaction between diosgenin analogues [DioA: diosgenin acetate (DAc) and (25)-5α,6β-dihydroxyspirostan-3β-ol acetate (DSol)] and cholesterol (Ch) monolayers at the air/water interface. The surface tension of pure and mixed lipid monolayers at 22 °C was measured by using the Langmuir method with a Teflon trough and a Nima 9002 tensiometer. The surface tension values were used to calculate the π-A isotherms and to determine the molecular surface areas.

The effect of divalent ions on L-α-phosphatidylcholine from egg yolk monolayers at the air/water interface.

The Langmuir monolayers of L-α-phosphatidylcholine from egg yolk were studied by Wilhelmy method. The surface pressure versus molecular area isotherm of lipid on pure water and different subphase (with a presence of divalent ions: Sr, Cd, Ba, Pb) was obtained. The limiting area of the isotherms depends on the presence of subphase ions.

Hyaluronic acid and phospholipid interactions useful for repaired articular cartilage surfaces-a mini review toward tribological surgical adjuvants.

This mini review is focused on the emerging nexus between the medical device and pharmaceutical industries toward the treatment of damaged articular cartilage. The physical rationale of hyaluronic acid and phospholipid preparations as tribological surgical adjuvants for repaired articular cartilage surfaces is explored, with directions for possible new research which have arisen due to the therapeutic advance of the physiochemical scalpel. Because synovial joint lubrication regimes become dysfunctional at articular cartilage lesion sites as a result of the regional absence of the surface active phospholipid layer and its inability to reform without surgical repair, hyaluronic acid and phospholipid intra-articular injections have yielded inconsistent efficacy outcomes and only short-term therapeutic benefits mostly due to non-tribological effects.

The Equilibria of Diosgenin-Phosphatidylcholine and Diosgenin-Cholesterol in Monolayers at the Air/Water Interface.

Diosgenin (Dio) has shown many treatment properties, but the most important property is cytotoxic activity in cancer cells. In this study, we investigated monolayers of Dio, cholesterol (Ch), and phosphatidylcholine (PC) at the air/water interface. The measurements were carried with a Langmuir Teflon trough and a Nima 9000 tensiometer program.

Equilibria Between Cell Membranes and Electrolyte Solution: Effect of Fatal Accidental Hypothermia.

Equilibria between the membranes of erythrocytes as well as thrombocytes and solution ions in fatal accidental hypothermia were analyzed using a theoretical four-equilibria model. The model was developed to determinate parameters characterizing cell membrane-surrounding ion interactions: the total surface concentrations of both acidic and basic groups C A, C B, and association constants K AH, K BOH. Knowledge of these parameters was necessary to calculate the theoretical values of surface charge density.

Changes in Surface Charge Density of Blood Cells in Fatal Accidental Hypothermia.

The objective of this research was to evaluate postmortem changes concerning electric charge of human erythrocytes and thrombocytes in fatal accidental hypothermia. The surface charge density values were determined on the basis of the electrophoretic mobility measurements of the cells conducted at various pH values of electrolyte solution. The surface charge of erythrocyte membranes after fatal accidental hypothermia increased compared to the control group within whole range of experimental pH values.

Phosphatidylcholine-fatty Alcohols Equilibria in Monolayers at the Air/Water Interface.

Monolayers of phosphatidylcholine (PC), tetradecanol (TD), hexadecanol (HD), octadecanol (OD) and eicosanol (E) and their binary mixtures were investigated at the air/water interface. The surface tension values of pure and mixed monolayers were used to calculate π-A isotherms. The surface tension measurements were carried out at 22 °C using a Teflon trough and a Nima 9000 tensiometer.

The effect of fatal carbon monoxide poisoning on the equilibria between cell membranes and the electrolyte solution.

The effect of fatal carbon monoxide poisoning on equilibria between cell membranes and surrounding ions was described using a theoretical four-equilibria model. The model was developed to obtain parameters characterizing the interactions between solution ions and erythrocyte or thrombocyte membrane surface. The parameters are the total surface concentrations of both acidic and basic groups C A, C B and their association constants with solution ions K AH, K BOH.