scholarly journals Quantitative Mapping of Free-Standing Lipid Membranes on Nano-Porous Mica Substrates

2018 ◽  
Author(s):  
Luca Costa ◽  
Adrian Carretero-Genevrier ◽  
Etienne Ferrain ◽  
Pierre-Emmanuel Milhiet ◽  
Laura Picas
Keyword(s):  
Lipid Membranes ◽  
Mechanical Response ◽  
Mechanical Stability ◽  
Biological Membranes ◽  
Chemical Properties ◽  
Elastic Response ◽  
Free Standing ◽  
Bending Modulus ◽  
Quantitative Mapping ◽  
Cell Adhesion And Migration

ABSTRACTThe physic-chemistry of biological membranes is at the origin of fundamental cellular functions such as vesicle trafficking, cell adhesion and migration1-3. Because most of intracellular shapes and local demixing of membranes take place in the nanometer scale, AFM becomes an extremely powerful technique to assess the properties of these biological membranes. Porous substrates provide an elegant strategy to avoid the conundrum of placing soft and thin biomembranes on hard substrates for AFM studies, although the surface chemistry make the actual substrates rather challenging setups. Here, we have engineered porous systems on the most widely used substrate in AFM, mica muscovite, with tunable pore sizes from some tens to few hundreds nanometers for biological applications. We show that free-standing bilayers on nano-porous can be obtained by using well-established vesicle spreading methods and that they display equivalent nano-mechanical stability and phsyco-chemical properties to that of membranes on conventional mica supports. By reducing the pore radius < 40 nm and limiting the contribution of membrane tension to the elastic response of free-standing membranes we estimate a bending modulus of 18 kbT and 73 kbT for DOPC and DPPC bilayers, respectively. The quantitative mapping of suspended membranes shows a different mechanical response at the pore rims, which is more pronounced for DPPC and suggest a different lipid ordering. We find that the combination of membrane bending and the different lipid packing at the edges of pores shapes the curvature of free-standing membranes on pores in the range of few tens of nm.

Atomic-Scale Analysis of Strain Relaxation Mechanisms in Ultra-Thin Metallic Films

2005 ◽  
Vol 880 ◽  
Author(s):  
M. Rauf Gungor ◽  
Dimitrios Maroudas
Keyword(s):  
Plastic Deformation ◽  
Void Growth ◽  
Large Scale ◽  
Mechanical Response ◽  
Strain Relaxation ◽  
Applied Strain ◽  
Atomic Scale ◽  
Elastic Response ◽  
Free Standing ◽  
Wide Range

AbstractA comprehensive computational analysis is presented of the atomistic mechanisms of strain relaxation over a wide range of applied biaxial tensile strain in free-standing Cu thin films. The analysis is based on large-scale isothermal-isostrain MD simulations using slab supercells with cylindrical voids normal to the film plane and extending throughout the film thickness. Our analysis has revealed various regimes in the film's mechanical response as the applied strain level increases. Following an elastic response at low strain (≶ 2%), plastic deformation occurs accompanied by emission of screw dislocations from the void surface and threading dislocations from the film surfaces, in parallel with generation of vacancies due to slip of jogged dislocations. At the lower strain range following the elastic-to-plastic deformation transition (⋚ 6%), void growth is the major strain relaxation mechanism, while at higher levels of applied strain (≥ 8%), a subsequent transition leads to a new plastic deformation regime where void growth plays a negligible role in the film strain relaxation.

Amphiphobic Septa Enhance the Mechanical Stability of Free-Standing Bilayer Lipid Membranes

Langmuir ◽  
2018 ◽  
Vol 34 (19) ◽  
pp. 5615-5622 ◽  
Author(s):  
Daichi Yamaura ◽  
Daisuke Tadaki ◽  
Shun Araki ◽  
Miyu Yoshida ◽  
Kohei Arata ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Mechanical Stability ◽  
Bilayer Lipid Membranes ◽  
Free Standing ◽  
Bilayer Lipid

Mechanical studies of hydrogel encapsulated membranes

2006 ◽  
Vol 926 ◽  
Author(s):  
Tae-Joon Jeon ◽  
Noah Malmstadt ◽  
Jacob Schmidt
Keyword(s):  
Lipid Bilayer ◽  
Lipid Membranes ◽  
Mechanical Stability ◽  
Electrical Measurement ◽  
Optical Measurements ◽  
Single Channels ◽  
Lipid Bilayer Membranes ◽  
Free Standing ◽  
Intimate Contact ◽  
High Throughput Drug Screening

ABSTRACTWe have encapsulated lipid bilayer membranes within a polyethylene glycol dimethacrylate hydrogel (PEG-DMA). These hydrogel encapsulated membranes (HEMs) are significantly longer-lived and more mechanically stable than traditional lipid membranes. Over 50 attempts, HEMs usually remained intact for over 48 hours, and some lasted up to 5 days. The electrical characteristics of the HEMs were consistently stable over this period of time. The approximate thickness of the HEM was measured to be 4.7±0.5 nm (n=25), consistent with a lipid bilayer. The resistance of the HEM remained over 10 GΩ over the period of electrical measurement. Simultaneous electrical and optical measurements showed that HEMs have unusual mechanical stability, whereas free-standing lipid membranes are typically susceptible to mechanical perturbation. The HEMs could withstand much greater applied pressures than unsupported membranes. In situ electrical and optical monitoring of the HEMs showed that the gel made intimate contact with the membrane, suggesting that direct mechanical support of the bilayer is the mechanism of membrane stabilization. Single channels of alpha-hemolysin, were incorporated into HEMs and continuously measured for over 4 days. Finally, combination of the HEM with an automated membrane microfluidic formation process is proposed as a prototype platform for high throughput drug screening or small molecule sensing.

Mechanically Stable Free-Standing Bilayer Lipid Membranes in Microfabricated Silicon Chips

2012 ◽  
Vol 1415 ◽  
Author(s):  
Azusa Oshima ◽  
Ayumi Hirano-Iwata ◽  
Yasuo Kimura ◽  
Michio Niwano
Keyword(s):  
Lipid Membranes ◽  
Mechanical Stability ◽  
Electric Properties ◽  
Bilayer Lipid Membranes ◽  
Dramatic Improvement ◽  
Free Standing ◽  
High Throughput Analysis ◽  
Bilayer Lipid ◽  
Gramicidin Channel ◽  
Insulator Layers

ABSTRACTIn this paper, we will discuss our recent approaches for improving the mechanical stability of free-standing bilayer lipid membranes (BLMs) by combining with BLM formation and microfabrication techniques. BLMs were prepared across a microaperture fabricated in a silicon (Si) chip and their mechanical stability and electric properties were investigated. BLMs suspended in a thin Si3N4 septum showed a dramatic improvement of BLM stability. The BLMs were resistant to voltage of ±1 V and the membrane lifetime was 15- ~40 h with and without incorporated channels. The membrane containing gramicidin channel exhibited tolerance to repetitive solution exchanges. At first, electric properties of the BLMs, such as noise level and current transient, were necessary to be improved. However, after coating the chip with insulator layers of Teflon and SiO2, total chip capacitance was reduced, leading to noise reduction (1-2 pA in peak-to-peak after low-pass filtering at 1 kHz) and elimination of current transients (< 0.5 ms). Since the vicinity of the aperture edge was remained uncoated, the BLMs formed in the Si chips still showed high mechanical stability after the insulator coatings. The mechanically stable BLMs having electric properties suitable for recording activities of biological channels will open up a variety of applications including high-throughput analysis of ion-channel proteins.

Mechanical and Microstructural Characterisation of a Free Standing Plasma Sprayed Alumina

1998 ◽  
Author(s):  
R.J. Damani
Keyword(s):  
Mechanical Response ◽  
Mechanical Stability ◽  
Subgrain Structure ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Electron Microscopic ◽  
Annealed Material ◽  
Phase Development ◽  
Material Conditions ◽  
Plasma Sprayed

Abstract Plasma spraying, commonly used for wear and heat resistant barriers, can be used to produce free-standing bulk ceramic parts as well. In this work the microstructure and phase development of a bulk plasma-sprayed alumina material with about 14 % porosity and splat like grains is investigated in the as-sprayed and various annealed material conditions, using electron microscopic and x-ray diffraction techniques. The fracture characteristics are investigated using standard CT specimens in in-situ SEM experiments. The mechanical response of the material is clearly a result of two features: the pronounced alignment of microstructure itself, and the occurrence of a splat-internal microcrack sub-structure in the as-sprayed condition. This microcrack substructure is a consequence of a splat internal columnar subgrain structure which occurs as a result of the rapid cooling conditions on deposition. The morphology of this subgrain structure and its phase composition is seen to change extensively on annealing. It is found that the mechanical behaviour of the as sprayed material is dominated by this internal subgrain structure, but the behaviour of sufficiently annealed material is dominated by the morphology and mechanical stability of the splat like grains themselves. The biggest change on annealing is not an overall sintering effect, but rather the recrystallisation of the splat internal substructure

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

Polymer-Graphene Nanoassemblies and their Applications in Cancer Theranostics

2020 ◽  
Vol 20 (11) ◽  
pp. 1340-1351 ◽  
Author(s):  
Ponnurengam M. Sivakumar ◽  
Matin Islami ◽  
Ali Zarrabi ◽  
Arezoo Khosravi ◽  
Shohreh Peimanfard
Keyword(s):  
Mechanical Stability ◽  
Chemical Properties ◽  
The Other ◽  
Hydrophilic Polymer ◽  
Two Dimensional ◽  
Normal Tissues ◽  
Physical Chemical ◽  
Anti Cancer ◽  
Good Biocompatibility ◽  
Cancer Theranostics

Background and objective: Graphene-based nanomaterials have received increasing attention due to their unique physical-chemical properties including two-dimensional planar structure, large surface area, chemical and mechanical stability, superconductivity and good biocompatibility. On the other hand, graphene-based nanomaterials have been explored as theranostics agents, the combination of therapeutics and diagnostics. In recent years, grafting hydrophilic polymer moieties have been introduced as an efficient approach to improve the properties of graphene-based nanomaterials and obtain new nanoassemblies for cancer therapy. Methods and results: This review would illustrate biodistribution, cellular uptake and toxicity of polymergraphene nanoassemblies and summarize part of successes achieved in cancer treatment using such nanoassemblies. Conclusion: The observations showed successful targeting functionality of the polymer-GO conjugations and demonstrated a reduction of the side effects of anti-cancer drugs for normal tissues.

scholarly journals The impact of orally administered gadolinium orthovanadate GdVO4:Eu3+ nanoparticles on the state of phospholipid bilayer of erythrocytes

2020 ◽  
Vol 45 (4) ◽  
pp. 389-395
Author(s):  
Anton Tkachenko ◽  
Anatolii Onishchenko ◽  
Vladimir Klochkov ◽  
Nataliya Kavok ◽  
Oksana Nakonechna ◽  
...  
Keyword(s):  
Fluorescent Probes ◽  
Lipid Membranes ◽  
Chemical Properties ◽  
Proton Donor ◽  
The State ◽  
Phospholipid Bilayer ◽  
Erythrocyte Membranes ◽  
Control Group ◽  
Donor Ability ◽  
The Impact

AbstractObjectivesTo assess the state of phospholipid bilayer of red blood cells (RBCs) in rats orally exposed to gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) during two weeks using fluorescent probes − ortho-hydroxy derivatives of 2,5-diaryl-1,3-oxazole.MethodsSteady-state fluorescence spectroscopy: a study by the environment-sensitive fluorescent probes − 2-(2′-OH-phenyl)-5-phenyl-1,3-oxazole (probe O1O) and 2-(2′-OH-phenyl)-phenanthro[9,10]-1,3-oxazole (probe PH7).ResultsNo significant changes are detected in the spectra of the fluorescent probes bound to the RBCs from the rats orally exposed to nanoparticles in comparison with the corresponding spectra of the probes bound to the cells from the control group of animals. This indicates that, in case of the rats orally exposed to nanoparticles, no noticeable changes in physico-chemical properties (i.e., in the polarity and the proton-donor ability) are observed in the lipid membranes of RBCs in the region, where the probes locate.ConclusionsNo changes in the physical and chemical properties of the erythrocyte membranes are detected in the region from glycerol backbones of phospholipids to the center of the phospholipid bilayer in the rats orally exposed to VNPs during 2 weeks.

Mechanical Response of Different Lattice Structures Fabricated Using the CLIP Technology

2016 ◽  
Author(s):  
Anil Saigal ◽  
John R. Tumbleston ◽  
Hendric Vogel
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Response ◽  
Elastic Response ◽  
Lattice Structures ◽  
Rhombic Dodecahedron ◽  
Structured Materials ◽  
Specific Strength ◽  
Strain Behavior ◽  
End Use ◽  
Continuous Liquid Interface Production

In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, ultralight, ultrastiff end-use parts. This research investigates the mechanical behavior of octahedral, octet, vertex centroid, dode, diamond, rhombi octahedron, rhombic dodecahedron and solid lattice structured polyacrylate fabricated using Continuous Liquid Interface Production (CLIP) technology based on 3D printing and additive manufacturing processes. The compressive stress-strain behavior of the lattice structures observed is typical of cellular structures which include a region of nominally elastic response, yielding, plastic strain hardening to a peak in strength, followed by a drop in flow stress to a plateau region and finally rapid hardening associated with contact of the deformed struts with each other as part of densification. It was found that the elastic modulus and strength of the various lattice structured materials are proportional to each other. In addition, it was found that the octahedral, octet and diamond lattice structures are amongst the most efficient based on the measured specific stiffness and specific strength.

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