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 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.

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 the air-water interface: Characterising biomimetic and natural hydrophobic surfaces using in situ atomic force microscopy

2019 ◽  
Vol 536 ◽  
pp. 363-371 ◽  
Author(s):  
Aaron Elbourne ◽  
Madeleine F. Dupont ◽  
Simon Collett ◽  
Vi Khanh Truong ◽  
XiuMei Xu ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Water Interface ◽  
Hydrophobic Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Air Water Interface

scholarly journals Investigation of Surface Behavior of DPPC and Curcumin in Langmuir Monolayers at the Air-Water Interface

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Guoqing Xu ◽  
Changchun Hao ◽  
Lei Zhang ◽  
Runguang Sun
Keyword(s):  
Langmuir Monolayers ◽  
Hydroxyl Groups ◽  
Water Interface ◽  
Mixed Monolayers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Air Water Interface ◽  
Compressibility Coefficient ◽  
Phase Behaviors ◽  
Thermodynamic Phase

Langmuir monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a mixture of DPPC with curcumin (CUR) have been investigated at the air-water interface through a combination of surface pressure measurements and atomic force microscopy (AFM) observation. By analyzing the correlation data of mean molecular areas, the compressibility coefficient, and other thermodynamic parameters, we obtained that the interaction between the two components perhaps was mainly governed by the hydrogen bonding between the amino group of DPPC and the hydroxyl groups of CUR. CUR markedly affected the surface compressibility, the thermodynamic stability, and the thermodynamic phase behaviors of mixed monolayers. The interaction between CUR and DPPC was sensitive to the components and the physical states of mixed monolayers under compression. Two-dimensional phase diagrams and interaction energies indicated that DPPC and CUR molecules were miscible in mixed monolayers. AFM images results were in agreement with these analyses results of experimental data. This study will encourage us to further research the application of CUR in the biomedical field.

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