scholarly journals Influence of membrane-cortex linkers on the extrusion of membrane tubes

2020 ◽  
Author(s):  
Alexandru Paraschiv ◽  
Thibaut Lagny ◽  
Evelyne Coudrier ◽  
Christian Vanhille Campos ◽  
Patricia Bassereau ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane ◽  
Optical Tweezers ◽  
Extrusion Force ◽  
Inhomogeneous System ◽  
Attachment Protein ◽  
Local Effects ◽  
Tube Extrusion ◽  
Wide Range

The cell membrane is an inhomogeneous system composed of phospholipids, sterols and proteins that can be directly attached to underlying cytoskeleton. The linkers between the membrane and the cytoskeleton are believed to have a profound effect on the mechanical properties of the cell membrane and its ability to reshape. Here we investigate the role of membrane-cortex linkers on the extrusion of membrane tubes using computer simulations and experiments. In simulations we find that the force for tube extrusion has a non-linear dependence on the density of membrane-cortex attachments: at a wide range of low and intermediate densities of linkers the force is not significantly influenced by the presence of membrane linking proteins and resembles that of the bare membrane. For large concentrations of linkers however the force substantially increases compared to the bare membrane. In both cases the linkers provided membrane tubes with increased stability against coalescence. We then pulled tubes from HEK cells using optical-tweezers for varying expression levels of the membrane-cortex attachment protein Ezrin. In line with simulations, we observed that overexpression of Ezrin led to an increased extrusion force, while Ezrin depletion had negligible effect on the force. Our results shed new light on the importance of local effects in membrane reshaping at the nanoscopic scales.

scholarly journals Role of combined cell membrane and wall mechanical properties regulated by polarity signals in cell budding

2020 ◽  
Vol 17 (6) ◽  
pp. 065011
Author(s):  
Kevin Tsai ◽  
Samuel Britton ◽  
Ali Nematbakhsh ◽  
Roya Zandi ◽  
Weitao Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane

scholarly journals The Flame Retardancy of Polyethylene Composites: From Fundamental Concepts to Nanocomposites

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5157
Author(s):  
Erfan Rezvani Ghomi ◽  
Fatemeh Khosravi ◽  
Zahra Mossayebi ◽  
Ali Saedi Ardahaei ◽  
Fatemeh Morshedi Dehaghi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flame Retardancy ◽  
Cost Efficiency ◽  
Research Papers ◽  
The Past ◽  
Wide Range ◽  
Fire Retardance ◽  
Low Toxicity ◽  
Implementing Strategies

Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality. However, its high flammability and rapid flame spread pose dangers for certain applications. Therefore, different flame-retardant (FR) additives are incorporated into PE to increase its flame retardancy. In this review article, research papers from the past 10 years on the flame retardancy of PE systems are comprehensively reviewed and classified based on the additive sources. The FR additives are classified in well-known FR families, including phosphorous, melamine, nitrogen, inorganic hydroxides, boron, and silicon. The mechanism of fire retardance in each family is pinpointed. In addition to the efficiency of each FR in increasing the flame retardancy, its impact on the mechanical properties of the PE system is also discussed. Most of the FRs can decrease the heat release rate (HRR) of the PE products and simultaneously maintains the mechanical properties in appropriate ratios. Based on the literature, inorganic hydroxide seems to be used more in PE systems compared to other families. Finally, the role of nanotechnology for more efficient FR-PE systems is discussed and recommendations are given on implementing strategies that could help incorporate flame retardancy in the circular economy model.

scholarly journals Exploring the Role of Nanoparticles in Enhancing Mechanical Properties of Hydrogel Nanocomposites

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 882 ◽  
Author(s):  
Josergio Zaragoza ◽  
Scott Fukuoka ◽  
Marcus Kraus ◽  
James Thomin ◽  
Prashanth Asuri
Keyword(s):  
Mechanical Properties ◽  
Elastic Moduli ◽  
Maximum Modulus ◽  
Polymer Particle ◽  
Particle Interactions ◽  
Polyacrylamide Hydrogels ◽  
The Past ◽  
Wide Range ◽  
Hydrogel Nanocomposites

Over the past few decades, research studies have established that the mechanical properties of hydrogels can be largely impacted by the addition of nanoparticles. However, the exact mechanisms behind such enhancements are not yet fully understood. To further explore the role of nanoparticles on the enhanced mechanical properties of hydrogel nanocomposites, we used chemically crosslinked polyacrylamide hydrogels incorporating silica nanoparticles as the model system. Rheological measurements indicate that nanoparticle-mediated increases in hydrogel elastic modulus can exceed the maximum modulus that can be obtained through purely chemical crosslinking. Moreover, the data reveal that nanoparticle, monomer, and chemical crosslinker concentrations can all play an important role on the nanoparticle mediated-enhancements in mechanical properties. These results also demonstrate a strong role for pseudo crosslinking facilitated by polymer–particle interactions on the observed enhancements in elastic moduli. Taken together, our work delves into the role of nanoparticles on enhancing hydrogel properties, which is vital to the development of hydrogel nanocomposites with a wide range of specific mechanical properties.

Role of Material Properties in Improving Sheet Formability in SPIF Process

2010 ◽  
Vol 139-141 ◽  
pp. 600-604 ◽  
Author(s):  
Ghulam Hussain ◽  
Nasir Hayat ◽  
Lin Gao
Keyword(s):  
Mechanical Properties ◽  
Single Point ◽  
Tensile Fracture ◽  
Forming Process ◽  
Thickness Strain ◽  
Wall Angle ◽  
Wide Range ◽  
Metal Forming Process ◽  
Sheet Formability

Single point incremental forming (SPIF) is a novel sheet metal forming process. Owing to unique deformation mechanism, this process improves the sheet formability as compared to the conventional stamping process. In the current paper, the mechanical properties and spifability (i.e. formability in SPIF) of a wide range of materials were tested. The mechanical properties were mainly determined through tensile testing and the spifability was evaluated using Varying Wall Angle Conical Frustum (VWACF) test. Each mechanical property was drawn against the improvement in sheet formability (i.e. difference of spifability and stampability) and the sole most influential property was identified. It was found that the improvement in formability increases with the increasing of true thickness strain at tensile fracture.

scholarly journals 3D Printing of Thermoplastic Elastomers: Role of the Chemical Composition and Printing Parameters in the Production of Parts with Controlled Energy Absorption and Damping Capacity

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3551
Author(s):  
Marina León-Calero ◽  
Sara Catherine Reyburn Valés ◽  
Ángel Marcos-Fernández ◽  
Juan Rodríguez-Hernandez
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
3D Printing ◽  
Energy Absorption ◽  
Thermoplastic Elastomers ◽  
Damping Capacity ◽  
Compression Tests ◽  
Wide Range ◽  
Printing Parameters

Additive manufacturing (AM) is a disruptive technology that enables one to manufacture complex structures reducing both time and manufacturing cost. Among the materials commonly used for AM, thermoplastic elastomers (TPE) are of high interest due to their energy absorption capacity, energy efficiency, cushion factor or damping capacity. Previous investigations have exclusively focused on the optimization of the printing parameters of commercial TPE filaments and the structures to analyse the mechanical properties of the 3D printed parts. In the present paper, the chemical, thermal and mechanical properties for a wide range of commercial thermoplastic polyurethanes (TPU) filaments were investigated. For this purpose, TGA, DSC, 1H-NMR and filament tensile strength experiments were carried out in order to determine the materials characteristics. In addition, compression tests have been carried out to tailor the mechanical properties depending on the 3D printing parameters such as: infill density (10, 20, 50, 80 and 100%) and infill pattern (gyroid, honeycomb and grid). The compression tests were also employed to calculate the specific energy absorption (SEA) and specific damping capacity (SDC) of the materials in order to establish the role of the chemical composition and the geometrical characteristics (infill density and type of infill pattern) on the final properties of the printed part. As a result, optimal SEA and SDC performances were obtained for a honeycomb pattern at a 50% of infill density.

scholarly journals Correlated flickering of erythrocytes membrane observed with dual time resolved membrane fluctuation spectroscopy under different d-glucose concentrations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Tapia ◽  
N. Vera ◽  
Joao Aguilar ◽  
M. González ◽  
S. A. Sánchez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane ◽  
Optical Tweezers ◽  
Glucose Concentration ◽  
Blood Cells ◽  
Mechanical Parameters ◽  
Generalized Polarization ◽  
Time Resolved ◽  
Bending Modulus ◽  
Fluctuation Amplitude

AbstractA correlated human red blood cell membrane fluctuation dependent on d-glucose concentration was found with dual time resolved membrane fluctuation spectroscopy (D-TRMFS). This new technique is a modified version of the dual optical tweezers method that has been adapted to measure the mechanical properties of red blood cells (RBCs) at distant membrane points simultaneously, enabling correlation analysis. Mechanical parameters under different d-glucose concentrations were obtained from direct membrane flickering measurements, complemented with membrane fluidity measurements using Laurdan Generalized Polarization (GP) Microscopy. Our results show an increase in the fluctuation amplitude of the lipid bilayer, and a decline in tension value, bending modulus and fluidity as d-glucose concentration increases. Metabolic mechanisms are proposed as explanations for the results.

scholarly journals Characterizing mechanics of membrane tether from relaxation curve obtained by optical tweezers

2020 ◽  
Author(s):  
Xuanling Li ◽  
Xiaoyu Song ◽  
Yinmei Li ◽  
Ming Li ◽  
Haowei Wang
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane ◽  
Optical Tweezers ◽  
Relaxation Curve ◽  
Membrane Tension ◽  
Protein Diffusion ◽  
Relaxation Curves ◽  
Membrane Tether ◽  
Cell Skeleton ◽  
The Relationship

AbstractOptical tweezers is a powerful tool in the study of membrane tension. Comparing to pulling out an entire membrane tether at one time, the step-like method is more efficient because multiple relaxation curves can be obtained from one membrane tether. However, there is few proper models that describe relaxation curves to characterize mechanical properties of cell membrane. Here we established a model to describe the relaxation curve of HeLa cells based on the relationship between membrane tether diameter and tensions. We obtained effective viscosities and static tensions by fitting relaxation curves to our model. We noticed the delicate structure of relaxation curves contains information of cell skeleton changes and protein diffusion. Our study paved a novel pathway to characterize the dynamics and mechanics of cell membrane.

The role of CD4 on mechanical properties of live cell membrane

2015 ◽  
Vol 104 (1) ◽  
pp. 239-244 ◽  
Author(s):  
Van-Chien Bui ◽  
Thi-Huong Nguyen
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane ◽  
Live Cell

Single-molecule Force Microscopy: A Powerful Tool for Studying the Mechanical Properties of Cell Membranes

2021 ◽  
Vol 17 ◽  
Author(s):  
Yan Shi ◽  
Mingjun Cai ◽  
Hongda Wang
Keyword(s):  
Mechanical Properties ◽  
Cell Membrane ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Cell Mechanics ◽  
Magnetic Tweezers ◽  
Adhesion Assay ◽  
Force Microscopy ◽  
Advantages And Disadvantages ◽  
Mechanical Signal

Background: Cell membrane is a physical barrier for cells, as well as an important structure with complex functions in cellular activities. The cell membrane can not only receive external mechanical signal stimulation and respond (e.g., cell migration, differentiation, tumorigenesis, growth), but it can also spontaneously exert force on the environment to regulate cellular activities (such as tissue repair, tumor metastasis, extracellular matrix regulation, etc.). Methods: This review introduces single-molecule force methods, such as atomic force microscopy, optical tweezers, magnetic tweezers, micropipette adhesion assay, tension gauge tethers, and traction force microscopy. Results: This review summarizes the principles, advantages, and disadvantages of single-molecule force methods developed in recent years, as well as their application in terms of force received and generated by cells. The study of cell mechanics enables us to understand the nature of mechanical signal transduction and the manifestation of the cell's movement. Conclusion: The study of the mechanical properties of the cell microenvironment leads to a gradual understanding of the important role of cell mechanics in development, physiology, and pathology. Recently developed combined methods are beneficial for further studying cell mechanics. The optimization of these methods and the invention of new methods enable the continuing research on cell mechanics.

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