Deposition of Lipid Bilayers with Atomic Force Microscopy

2005 ◽  
Vol 11 (S03) ◽  
pp. 44-47 ◽  
Author(s):  
G. D. Tavares ◽  
M. C. de Oliveira ◽  
J. M. C. Vilela ◽  
M. S. Andrade
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Flat Substrate ◽  
Atomic Force ◽  
Lipid Mixtures ◽  
A Cell ◽  
Integral Proteins ◽  
Spherical Vesicles

Biological membranes are constituted of lipids organized as a two dimensional bilayer supporting peripheral and integral proteins, providing a barrier between the inside and the outside of a cell [1]. Similar membranes can be prepared from the lipid mixtures forming liposomes. The liposomes are multi or unilamellar spherical vesicles in which an aqueous volume is enclosed and can be used to encapsulate some drugs [2]. In order to better expose the details of their structure, these membranes are generally deposited on the surface of a flat substrate. These supported planar lipid membranes can also provide a model system for investigating the properties and functions of the complex cell membrane and membrane mediated processes such as recognition events and biological signal transduction. Various methods have been used to create artificial lipid membranes supported on a solid surface, being the most used the Langmuir-Blodgett monolayers formation [3], the vesicle fusion or liposome adsorption [4] and the solution spreading [5].

scholarly journals AFM nanoindentation reveals decrease of elastic modulus of lipid bilayers near freezing point of water

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Calum Gabbutt ◽  
Wuyi Shen ◽  
Jacob Seifert ◽  
Sonia Contera
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Structural Changes ◽  
Freezing Point ◽  
Liquid Environment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging ◽  
Underlying Causes ◽  
Irreversible Injury

AbstractCell lipid membranes are the primary site of irreversible injury during freezing/thawing and cryopreservation of cells, but the underlying causes remain unknown. Here, we probe the effect of cooling from 20 °C to 0 °C on the structure and mechanical properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers using atomic force microscopy (AFM) imaging and AFM-based nanoindentation in a liquid environment. The Young’s modulus of elasticity (E) at each temperature for DPPC was obtained at different ionic strengths. Both at 20 mM and 150 mM NaCl, E of DPPC bilayers increases exponentially –as expected–as the temperature is lowered between 20 °C and 5 °C, but at 0 °C E drops from the values measured at 5 °C. Our results support the hypothesis that mechanical weakening of the bilayer at 0 °C  is produced by  structural changes at the lipid-fluid interface.

scholarly journals Interaction of the human N-Ras protein with lipid raft model membranes of varying degrees of complexity

2014 ◽  
Vol 395 (7-8) ◽  
pp. 779-789 ◽  
Author(s):  
Alexander Vogel ◽  
Jörg Nikolaus ◽  
Katrin Weise ◽  
Gemma Triola ◽  
Herbert Waldmann ◽  
...  
Keyword(s):  
Lipid Raft ◽  
Lipid Membranes ◽  
Model Systems ◽  
Stable Phase ◽  
Force Microscopy ◽  
Ras Protein ◽  
Atomic Force ◽  
Lipid Mixtures ◽  
Functional Aspects ◽  
And Function

Abstract Ternary lipid mixtures composed of cholesterol, saturated (frequently with sphingosine backbone), and unsaturated phospholipids show stable phase separation and are often used as model systems of lipid rafts. Yet, their ability to reproduce raft properties and function is still debated. We investigated the properties and functional aspects of three lipid raft model systems of varying degrees of biological relevance – PSM/POPC/Chol, DPPC/POPC/Chol, and DPPC/DOPC/Chol – using 2H solid-state nuclear magnetic resonance (NMR) spectroscopy, fluorescence microscopy, and atomic force microscopy. While some minor differences were observed, the general behavior and properties of all three model mixtures were similar to previously investigated influenza envelope lipid membranes, which closely mimic the lipid composition of biological membranes. For the investigation of the functional aspects, we employed the human N-Ras protein, which is posttranslationally modified by two lipid modifications that anchor the protein to the membrane. It was previously shown that N-Ras preferentially resides in liquid-disordered domains and exhibits a time-dependent accumulation in the domain boundaries of influenza envelope lipid membranes. For all three model mixtures, we observed the same membrane partitioning behavior for N-Ras. Therefore, we conclude that even relatively simple models of raft membranes are able to reproduce many of their specific properties and functions.

Phase Transitions in Phospholipid Monolayers Studied by Atomic Force Microscopy and Langmuir-Blodgett Technique

2008 ◽  
Vol 59 (11) ◽  
Author(s):  
Maria Tomoaia-Cotisel ◽  
Aurora Mocanu
Keyword(s):  
Atomic Force Microscopy ◽  
Lipid Membrane ◽  
Phase Behaviour ◽  
Membrane Interface ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
Phospholipid Monolayers ◽  
Air Water Interface ◽  
Condensed Liquid

The phase behaviour and surface structure of dipalmitoyl phosphatidyl choline (DPPC) monolayers at the air/water interface, in the absence and the presence of procaine, have been investigated by Langmuir-Blodgett (LB) technique and atomic force microscopy. The LB films were transferred on mica, at a controlled surface pressure, characteristic for the expanded liquid to condensed liquid phase transition of pure DPPC monolayers. The results indicate that procaine penetrates into and specifically interacts with phospholipid monolayers stabilizing the lipid membrane interface.

scholarly journals Atomic Force Microscopy Studies of Lipophosphoglycan (LPG) Molecules in Lipid Bilayers

2003 ◽  
Author(s):  
JULIE A LAST ◽  
TINA HUBER ◽  
DARRYL Y SASAKI ◽  
BRIAN SALVATORE ◽  
SALVATORE J TURCO
Keyword(s):  
Atomic Force Microscopy ◽  
Lipid Bilayers ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Optical, Structural and Electrical Properties of Electrochemical Synthesis of Thin Film of Polyaniline

2018 ◽  
Vol 15 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Morphological Studies ◽  
Atomic Force ◽  
Vis Spectroscopy ◽  
Structural And Electrical Properties ◽  
A Cell ◽  
Ft Ir ◽  
Ir And Raman

Polyaniline membranes of aniline were produced using an electrochemical method in a cell consisting of two poles. The effect of the vaccination was observed on the color of membranes of polyaniline, where analysis as of blue to olive green paints. The sanction of PANI was done by FT-IR and Raman techniques. The crystallinity of the models was studied by X-ray diffraction technique. The different electronic transitions of the PANI were determined by UV-VIS spectroscopy. The electrical conductivity of the manufactured samples was measured by using the four-probe technique at room temperature. Morphological studies have been determined by Atomic force microscopy (AFM). The structural studies have been measured by (SEM).

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