scholarly journals Interfacial Interactions and Nanostructure Changes in DPPG/HD Monolayer at the Air/Water Interface

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Huaze Zhu ◽  
Runguang Sun ◽  
Tao Zhang ◽  
Changchun Hao ◽  
Pengli Zhang ◽  
...  
Keyword(s):  
Lung Surfactant ◽  
Compression Modulus ◽  
Metabolic Energy ◽  
Excess Gibbs Free Energy ◽  
Valuable Insight ◽  
Water Interface ◽  
Force Microscopy ◽  
Lung Expansion ◽  
Air Water Interface ◽  
Pressure Area

Lung surfactant (LS) plays a crucial role in regulating surface tension during normal respiration cycles by decreasing the work associated with lung expansion and therefore decreases the metabolic energy consumed. Monolayer surfactant films composed of a mixture of phospholipids and spreading additives are of optional utility for applications in lung surfactant-based therapies. A simple, minimal model of such a lung surfactant system, composed of 1,2-dipalmitoyl-sn-glycero-3-[phosphor-rac-(1-gylcerol)] (DPPG) and hexadecanol (HD), was prepared, and the surface pressure-area (π-A) isotherms and nanostructure characteristics of the binary mixture were investigated at the air/water interface using a combination of Langmuir-Blodgett (LB) and atomic force microscopy (AFM) techniques. Based on the regular solution theory, the miscibility and stability of the two components in the monolayer were analyzed in terms of compression modulus (Cs-1) , excess Gibbs free energy (ΔGexcπ) , activity coefficients (γ), and interaction parameter (ξ). The results of this paper provide valuable insight into basic thermodynamics and nanostructure of mixed DPPG/HD monolayers; it is helpful to understand the thermodynamic behavior of HD as spreading additive in LS monolayer with a view toward characterizing potential improvements to LS performance brought about by addition of HD to lung phospholipids.

Imaging Phospholipid Arrangement in Pultonary Surfactant Using Atomic Force Microscopy

2000 ◽  
Vol 6 (S2) ◽  
pp. 870-871
Author(s):  
K. Nag ◽  
F. Possmayer ◽  
N. O. Petersen ◽  
S. A. Hearn
Keyword(s):  
Surface Tension ◽  
Lung Surfactant ◽  
Water Interface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Alveolar Collapse ◽  
Air Water Interface ◽  
Associated Proteins ◽  
Gel Phase ◽  
Gel Transition

Lung surfactant stabilizes the pulmonary air-water interface, by enriching this interface with films of amphipathic phospholipids. These films reduce the surface tension of the air-water interface to very low values (∼ 1 mN/m) at end expiration and prevents alveolar collapse. Surfactant contains mainly phospholipids (90%), and small amounts of associated proteins. Among the phospholipids, saturated dipalmitoylphosphatidylcholine (DPPC) and monounsaturated phosphatidylcholine are the main surfactant components, although significant amounts of other lipids are also present (1). DPPC is the only component of surfactant which exists in gel phase at physiological temperature, films of which can reduce the air-water surface tension to low values. DPPC films can undergo a fluid to gel transition with increase in the molecular packing leading to superstructures or domains (2). However it is not clear how the molecules of surfactant pack at the air-water interface to form highly compact films, and if DPPC phase segregate in such films.

scholarly journals Nanoparticle interaction with model lung surfactant monolayers

2009 ◽  
Vol 7 (suppl_1) ◽  
Author(s):  
Rakesh Kumar Harishchandra ◽  
Mohammed Saleem ◽  
Hans-Joachim Galla
Keyword(s):  
Surface Properties ◽  
Self Assembly ◽  
Current Knowledge ◽  
Surface Film ◽  
Lung Surfactant ◽  
Hydrophobic Surface ◽  
Surface Pattern ◽  
Lipid Monolayers ◽  
Water Interface ◽  
Air Water Interface

One of the most important functions of the lung surfactant monolayer is to form the first line of defence against inhaled aerosols such as nanoparticles (NPs), which remains largely unexplored. We report here, for the first time, the interaction of polyorganosiloxane NPs (AmorSil20: 22 nm in diameter) with lipid monolayers characteristic of alveolar surfactant. To enable a better understanding, the current knowledge about an established model surface film that mimics the surface properties of the lung is reviewed and major results originating from our group are summarized. The pure lipid components dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol have been used to study the biophysical behaviour of their monolayer films spread at the air–water interface in the presence of NPs. Film balance measurements combined with video-enhanced fluorescence microscopy have been used to investigate the formation of domain structures and the changes in the surface pattern induced by NPs. We are able to show that NPs are incorporated into lipid monolayers with a clear preference for defect structures at the fluid–crystalline interface leading to a considerable monolayer expansion and fluidization. NPs remain at the air–water interface probably by coating themselves with lipids in a self-assembly process, thereby exhibiting hydrophobic surface properties. We also show that the domain structure in lipid layers containing surfactant protein C, which is potentially responsible for the proper functioning of surfactant material, is considerably affected by NPs.

Temperature dependence of dipalmitoyl phosphatidylcholine monolayer stability

1981 ◽  
Vol 51 (5) ◽  
pp. 1108-1114 ◽  
Author(s):  
J. Goerke ◽  
J. Gonzales
Keyword(s):  
Phase Transition ◽  
Lung Surfactant ◽  
Principal Component ◽  
Water Interface ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Phase Transition Temperatures ◽  
Air Water Interface ◽  
Different Temperatures ◽  
Monolayer Stability ◽  
Isolated Rat

Dipalmitoyl phosphatidylcholine is the principal component of lung surfactant, and knowledge of its behavior as a film spread at the air-water interface is essential for understanding how lung surfactant itself works. We therefore studied the collapse rates of very low surface tension air-water monolayers of dipalmitoyl, dimyristoyl, and palmitoyl-myristoyl phosphatidylcholines at different temperatures. In each case we found that the monolayers abruptly became unstable at temperature 3–4 degree C above their bulk lipid-water phase transition temperatures (Tc). This accords with a comparable increase in Tc occurring in bulk systems subjected to high pressure. These findings are also consistent with the behavior of isolated rat lungs, which have been found to require higher transmural pressures to maintain a given volume on deflation when kept at temperature above the Tc of dipalmitoyl phosphatidylcholine.

scholarly journals Batch Production of High-Quality Graphene Grids for Cryo-EM: Cryo-EM Structure of Methylococcus capsulatus Soluble Methane Monooxygenase Hydroxylase

2021 ◽  
Author(s):  
Eungjin Ahn ◽  
byungchul Kim ◽  
uhn-soo Cho
Keyword(s):  
Protein Denaturation ◽  
Methane Monooxygenase ◽  
Atomic Layer ◽  
Water Interface ◽  
Methylococcus Capsulatus ◽  
Force Microscopy ◽  
Voltage Electron ◽  
Soluble Methane Monooxygenase ◽  
Air Water Interface ◽  
Scanning Em

Cryogenic electron microscopy (cryo-EM) has become a widely used tool for determining protein structure. Despite recent advances in instruments and algorithms, sample preparation remains a major bottleneck for several reasons, including protein denaturation at the air/water interface and the presence of preferred orientations and nonuniform ice layers. Graphene, a two-dimensional allotrope of carbon consisting of a single atomic layer, has recently attracted attention as a near-ideal support film for cryo-EM that can overcome these challenges because of its superior properties, including mechanical strength and electrical conductivity. Graphene minimizes background noise and provides a stable platform for specimens under a high-voltage electron beam and cryogenic conditions. Here, we introduce a reliable, easily implemented, and reproducible method of producing 36 graphene-coated grids at once within 1.5 days. The quality of the graphene grids was assessed using various tools such as scanning EM, Raman spectroscopy, and atomic force microscopy. To demonstrate their practical application, we determined the cryo-EM structure of Methylococcus capsulatus soluble methane monooxygenase hydroxylase (sMMOH) at resolutions of 2.9 and 2.4 angstrom using Quantifoil and graphene-coated grids, respectively. We found that the graphene-coated grid has several advantages; for example, it requires less protein, enables easy control of the ice thickness, and prevents pro-tein denaturation at the air/water interface. By comparing the cryo-EM structure of sMMOH with its crystal structure, we revealed subtle yet significant geometrical differences at the non-heme di-iron center, which may better indicate the active site configuration of sMMOH in the resting/oxidized state.

scholarly journals Air–water interface of submerged superhydrophobic surfaces imaged by atomic force microscopy

2017 ◽  
Vol 8 ◽  
pp. 1671-1679 ◽  
Author(s):  
Markus Moosmann ◽  
Thomas Schimmel ◽  
Wilhelm Barthlott ◽  
Matthias Mail
Keyword(s):  
Atomic Force Microscopy ◽  
Current Knowledge ◽  
Biological Species ◽  
Optical Methods ◽  
Water Interface ◽  
Contact Mode ◽  
Structured Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Air Water Interface

Underwater air retention of superhydrophobic hierarchically structured surfaces is of increasing interest for technical applications. Persistent air layers (the Salvinia effect) are known from biological species, for example, the floating fern Salvinia or the backswimmer Notonecta. The use of this concept opens up new possibilities for biomimetic technical applications in the fields of drag reduction, antifouling, anticorrosion and under water sensing. Current knowledge regarding the shape of the air–water interface is insufficient, although it plays a crucial role with regards to stability in terms of diffusion and dynamic conditions. Optical methods for imaging the interface have been limited to the micrometer regime. In this work, we utilized a nondynamic and nondestructive atomic force microscopy (AFM) method to image the interface of submerged superhydrophobic structures with nanometer resolution. Up to now, only the interfaces of nanobubbles (acting almost like solids) have been characterized by AFM at these dimensions. In this study, we show for the first time that it is possible to image the air–water interface of submerged hierarchically structured (micro-pillars) surfaces by AFM in contact mode. By scanning with zero resulting force applied, we were able to determine the shape of the interface and thereby the depth of the water penetrating into the underlying structures. This approach is complemented by a second method: the interface was scanned with different applied force loads and the height for zero force was determined by linear regression. These methods open new possibilities for the investigation of air-retaining surfaces, specifically in terms of measuring contact area and in comparing different coatings, and thus will lead to the development of new applications.

Role of Tail−Tail Interactions versus Head-Group−Subphase Interactions in Pressure−Area Isotherms of Fatty Amines at the Air−Water Interface. 2. Time Dependence

Langmuir ◽  
1997 ◽  
Vol 13 (20) ◽  
pp. 5440-5446 ◽  
Author(s):  
P. Ganguly ◽  
D. V. Paranjape ◽  
K. R. Patil ◽  
Murali Sastry ◽  
F. Rondelez
Keyword(s):  
Time Dependence ◽  
Head Group ◽  
Water Interface ◽  
Fatty Amines ◽  
Air Water Interface ◽  
Pressure Area
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