The phases of insoluble monolayers: Comparison between the surface pressure‐molecular area (Π‐A) diagram and shear modulus measurements

1983 ◽  
Vol 78 (7) ◽  
pp. 4776-4777 ◽  
Author(s):  
K. Miyano ◽  
B. M. Abraham ◽  
J. B. Ketterson ◽  
S. Q. Xu
Keyword(s):  
Shear Modulus ◽  
Surface Pressure ◽  
Molecular Area

scholarly journals Effects of Concentration and Surface Pressure on MBP Interaction with Cholesterol in Langmuir Films

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Lei Zhang ◽  
Changchun Hao ◽  
Guoqing Xu ◽  
Runguang Sun
Keyword(s):  
Surface Morphology ◽  
Surface Pressure ◽  
Protein Concentration ◽  
Molecular Mechanisms ◽  
Convincing Evidence ◽  
Langmuir Films ◽  
Domain Formation ◽  
Molecular Area ◽  
Lateral Membrane ◽  
Lateral Organization

Predicting the mechanism of MBP binding to cholesterol is meaningful in understanding how MBP participate in lateral membrane organization. The interaction of MBP with cholesterol monolayer was investigated at three surface pressures on 10 mM Tris-HCl buffer with the different concentrations of MBP. The results show that π-A isotherms shift to larger molecular area at all pressures. By means of analyzing π-T curves, a surface pressure increase was obtained. Results indicated that the greater the protein concentration in the subphase, the larger the increase of surface pressure. In addition, changes in monolayer surface morphology and domain formation were performed by AFM. These results provide more direct and convincing evidence for the MBP interaction with cholesterol. The MBP-cholesterol interaction suggests a significant concentrations and surface pressure dependence and is probably governed by hydrogen bonds. The date presented could help to understand at least one of the molecular mechanisms through which MBP affects lateral organization of the cholesterol membrane.

scholarly journals Thermodynamic Analysis of Myelin Basic Protein Adsorbed on Liquid Crystalline Dioleoylphosphatidylcholine Monolayer

Scanning ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Zhang Lei ◽  
Sun Runguang ◽  
Hao Changchun ◽  
Yang Huihui ◽  
Hu Chengxi
Keyword(s):  
Myelin Basic Protein ◽  
Surface Pressure ◽  
Liquid Crystalline ◽  
Basic Protein ◽  
Hydrophobic Interactions ◽  
Mass Conservation ◽  
Conservation Equation ◽  
Molecular Area ◽  
Unsaturated Lipid ◽  
Mass Conservation Equation

To investigate the stability and dynamic characteristics of monolayer adsorbed on unsaturated lipid dioleoylphosphatidylcholine (DOPC) with varying concentrations of myelin basic protein (MBP), the system is studied by applying Langmuir technique and making atomic force microscope (AFM) observation, which is based on the mass conservation equation analysis method referred to in the thermodynamics theory. As indicated by surface pressure-mean molecular area (π−A) and surface pressure-adsorption time (π−T) isotherms, the physical properties of monolayer derived from the interaction of varying concentrations of MBP with liquid crystalline unsaturated lipid DOPC molecules were qualitatively studied. As revealed by surface morphology analysis with AFM, the micro region was expanded as the concentration of MBP in the subphase was on the increase, suggesting that hydrophobic interactions led to the MBP insertion, thus causing accumulation of the MBP on the surface of the monolayer. Experimental results have demonstrated that the partition coefficient of the interaction between MBP and unsaturated phospholipid DOPC and the molecular area of MBP adsorbed on the monolayer film was calculated using the mass conservation equation. In addition, not only does the varying concentration of MBP in the subphase exerts significant effects on the arrangement and conformation of DOPC monolayer, it also has certain guiding significance to exploring the structural changes to biofilm supramolecular aggregates as well as the pathogenesis and treatment of related diseases.

scholarly journals Surface areas of 1-palmitoyl phosphatidylcholines and their interactions with cholesterol

1987 ◽  
Vol 245 (2) ◽  
pp. 455-462 ◽  
Author(s):  
R W Evans ◽  
M A Williams ◽  
J Tinoco
Keyword(s):  
Double Bond ◽  
Surface Pressure ◽  
Trans Double Bond ◽  
Double Bonds ◽  
Molecular Area ◽  
Monolayer Films ◽  
Surface Areas ◽  
Mixed Films ◽  
Carbon Acid ◽  
Carbon Series

1-Palmitoyl phosphatidylcholines (1-palmitoyl PCs), in which the 2-position was occupied respectively by C10:0, C12:0, C14:0, C14:1, n-7, C16:0, C16:1, n-7, C18:0, C18:1(t), n-9, C18:1, n-9, C18:2, n-6, C18:3, N-3, C18:3, n-6, C18:3(5t,9,12), C22:0, C22:1, n-9, C22:2, n-6, C22:3, n-3, C22:4, n-6, C22:5, n-6 or C22:6, n-3 fatty acids, were studied as monolayer films at the air/water interface. Results for molecular area indicated that the areas of the PC (phosphatidylcholine) did not continuously decrease as the length of one chain increased. For series of saturated, monoenoic and dienoic 1-palmitoyl PCs the smallest molecular area was occupied by the PC containing a 20-carbon acid at the 2-position. In the 18-carbon series, introduction of the first and third cis double bonds caused a large increase in molecular area, but in the 22-carbon series the first and second cis double bonds produced large increases in molecular area. Molecules containing three or more cis double bonds varied little in molecular area, regardless of chain length (18-22 carbon atoms). The influence of a trans double bond was intermediate between that of a saturated and a cis double bond. The 18- and 22-carbon series of PCs were studied in mixed monolayers with cholesterol and desmosterol. Condensation of molecular areas occurred in all sterol PC mixed films, and similar results were obtained with cholesterol and desmosterol. Condensation of PC containing a cis or trans double bond within 10 carbon atoms of the carboxy group initially increased with increasing surface pressure. Condensation of other PCs decreased as surface pressure increased. All cis- or trans-unsaturated PCs condensed maximally in mixtures of approximately equimolar ratios with sterols, but saturated PCs condensed to the greatest extent in mixtures that contained about 30 mol% sterol.

scholarly journals Influence of Potassium Ions on Act of Amphotericin B to the DPPC/Chol Mixed Monolayer at Different Surface Pressures

Membranes ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 84
Author(s):  
Juan Wang
Keyword(s):  
Amphotericin B ◽  
Mammalian Cell ◽  
Surface Pressure ◽  
High Pressures ◽  
High Surface ◽  
Potassium Ions ◽  
Molecular Area ◽  
Mixed Monolayer ◽  
Langmuir Blodgett Films ◽  
And Function

Amphotericin B (AmB) is an antifungal drug that rarely develops resistance. It has an affinity with the cholesterol on mammalian cell membranes, disrupting the structure and function of the membranes, which are also affected by potassium ions. However, the mechanism is unclear. In this paper, the Langmuir monolayer method was used to study the effects of potassium ions on the surface pressure–mean molecular area of isotherms, elastic modulus and the surface pressure–time curves of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol (DPPC/Chol) monolayer and a DPPC/Chol/AmB monolayer. The morphology and thickness of the Langmuir–Blodgett films were studied via atomic force microscopy. The results showed that AmB can increase the mean molecular area of the DPPC/Chol mixed monolayer at low pressures (15 mN/m) but reduces it at high pressures (30 mN/m). The potassium ions may interfere with the effect of AmB in different ways. The potassium ions can enhance the influence of AmB on the stability of monolayer at low surface pressures, but weaken it at high surface pressures. The potassium ions showed significant interference with the interaction between AmB and the cholesterol-enriched region. The results are helpful for us to understand how the effect of amphotericin B on the phospholipid membrane is interfered with by potassium ions when amphotericin B enters mammalian cell membrane.

scholarly journals Effects of Carboxyl or Amino Group Modified InP/ZnS Nanoparticles Toward Simulated Lung Surfactant Membrane

2021 ◽  
Vol 9 ◽  
Author(s):  
Juan Wang ◽  
Shun Feng ◽  
Jie Liu ◽  
Rui-Lin Liu
Keyword(s):  
Elastic Modulus ◽  
Surface Pressure ◽  
Early Stage ◽  
Lung Surfactant ◽  
Optical Probe ◽  
Molecular Area ◽  
Mixed Monolayer ◽  
Toxicological Effects ◽  
Lung Health

Quantum dots (QDs) as a promising optical probe have been widely used for in vivo biomedical imaging; especially enormous efforts recently have focused on the potential toxicity of QDs to the human body. The toxicological effects of the representative InP/ZnS QDs as a cadmium-free emitter are still in the early stage and have not been fully unveiled. In this study, the DPPC/DPPG mixed monolayer was used to simulate the lung surfactant monolayer. The InP/ZnS-COOH QDs and InP/ZnS-NH2 QDs were introduced to simulate the lung surfactant membrane’s environment in the presence of InP/ZnS QDs. The effects of InP/ZnS QDs on the surface behavior, elastic modulus, and stability of DPPC/DPPG mixed monolayer were explored by the surface pressure-mean molecular area isotherms and surface pressure-time curves. The images observed by Brewster angle microscope and atomic force microscope showed that the InP/ZnS QDs affected the morphology of the monolayer. The results further demonstrated that the InP/ZnS QDs coated with different surface groups can obviously adjust the mean molecular area, elastic modulus, stability, and microstructure of DPPC/DPPG mixed monolayer. Overall, this work provided useful information for in-depth understanding of the effects of the −COOH or −NH2 group coated InP/ZnS QDs on the surface of lung surfactant membrane, which will help scientists to further study the physiological toxicity of InP/ZnS QDs to lung health.

scholarly journals Langmuir-Blodgett Films of Supported Polyester Dendrimers

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Rocío Redón ◽  
M. Pilar Carreón-Castro ◽  
F. J. Mendoza-Martínez
Keyword(s):  
Surface Pressure ◽  
Dendritic Structure ◽  
The Self ◽  
Langmuir Films ◽  
Interfacial Behavior ◽  
Brewster Angle Microscopy ◽  
Molecular Area ◽  
Langmuir Blodgett ◽  
Self Assembling ◽  
Langmuir Blodgett Films

Amphiphiles with a dendritic structure are attractive materials as they combine the features of dendrimers with the self-assembling properties and interfacial behavior of water-air affinities. We have synthesized three generations of polyester dendrimers and studied their interfacial properties on the Langmuir films. The behavior obtained was, as a rule, the lowest generation dendrimers behaving like traditional amphiphiles and the larger molecules presenting complicated isotherms. The Langmuir films of these compounds have been characterized by their surface pressure versus molecular area (π/A) and Brewster angle microscopy (BAM) observations.

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