Cell Palpation System Based on a Force Measurement by Optical Tweezers for Investigation of Local Mechanical Properties of a Cell Membrane

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.

Download Full-text

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

10.1101/2020.09.06.285353 ◽

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.

Download Full-text

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

Current Analytical Chemistry ◽

10.2174/1573411017666210602144602 ◽

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.

Download Full-text

Mechanical Properties of Breast Cancer Cell Membrane Studied with Optical Tweezers

Chinese Physics Letters ◽

10.1088/0256-307x/21/12/062 ◽

2004 ◽

Vol 21 (12) ◽

pp. 2543-2546 ◽

Cited By ~ 15

Author(s):

Guo Hong-Lian ◽

Liu Chun-Xiang ◽

Duan Jian-Fa ◽

Jiang Yu-Qiang ◽

Han Xue-Hai ◽

...

Keyword(s):

Breast Cancer ◽

Mechanical Properties ◽

Cell Membrane ◽

Cancer Cell ◽

Optical Tweezers ◽

Breast Cancer Cell

Download Full-text

Flow arrest in the plasma membrane

10.1101/575456 ◽

2019 ◽

Cited By ~ 2

Author(s):

Michael Chein ◽

Eran Perlson ◽

Yael Roichman

Keyword(s):

Mechanical Properties ◽

Plasma Membrane ◽

Cell Membrane ◽

Domain Size ◽

Decay Length ◽

Neurotrophin Receptors ◽

Long Range Correlations ◽

Fluid Membranes ◽

A Cell ◽

Do So

AbstractThe arrangement of receptors in the plasma membrane strongly affects the ability of a cell to sense its environment both in terms of sensitivity and in terms of spatial resolution. The spatial and temporal arrangement of the receptors is affected in turn by the mechanical properties and the structure of the cell membrane. Here we focus on characterizing the flow of the membrane in response to the motion of a protein embedded in it. We do so by measuring the correlated diffusion of extracellularly tagged transmembrane neurotrophin receptors TrkB and p75 on transfected neuronal cells. In accord with previous reports, we find that the motion of single receptors exhibits transient confinement to sub-micron domains. We confirm predictions based on hydrodynamics of fluid membranes, finding long-range correlations in the motion of the receptors in the plasma membrane. However, we discover that these correlations do not persist for long ranges, as predicted, but decay exponentially, with a typical decay length on the scale of the average confining domain size.

Download Full-text

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

10.1101/2020.07.28.224741 ◽

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.

Download Full-text

Measurement of the mechanical properties of single Synechocystis sp. strain PCC6803 cells in different osmotic concentrations using a robot-integrated microfluidic chip

Lab on a Chip ◽

10.1039/c7lc01245d ◽

2018 ◽

Vol 18 (8) ◽

pp. 1241-1249 ◽

Cited By ~ 10

Author(s):

Di Chang ◽

Shinya Sakuma ◽

Kota Kera ◽

Nobuyuki Uozumi ◽

Fumihito Arai

Keyword(s):

Mechanical Properties ◽

Optical Tweezers ◽

Microfluidic Chip ◽

A Cell ◽

Synechocystis Sp

We measured the stiffness of a cell as small as 2 μm using a robot-integrated microfluidic chip and optical tweezers.

Download Full-text

Extracting elastic properties and prestress of a cell using atomic force microscopy

Journal of Materials Research ◽

10.1557/jmr.2009.0121 ◽

2009 ◽

Vol 24 (3) ◽

pp. 1167-1171 ◽

Cited By ~ 2

Author(s):

C.Y. Zhang ◽

Y.W. Zhang

Keyword(s):

Mechanical Properties ◽

Atomic Force Microscopy ◽

Elastic Modulus ◽

Analytical Solution ◽

Cell Membrane ◽

Soft Phase ◽

Force Microscopy ◽

Apparent Modulus ◽

Atomic Force ◽

A Cell

An analytical solution was derived for the indentation of a cell using atomic force microscopy. It was found that the contribution of the cell membrane to the overall indentation stiffness is dependent on the size of the indenter. When a small indenter [for example, an atomic force microscopy (AFM) tip] is used to probe the mechanical properties of cells, the cell membrane and its prestress were important in interpreting indentation data. The solution allows the partition of contributions from the membrane and the interior soft phase. The apparent elastic modulus of the cell and the prestress of the cell membrane can be extracted. In addition, the modulus of the cell membrane could be estimated from the extracted apparent modulus if the interior soft phase of the cell was known and vice versa. However, when a large indenter is used (for example, a microbead attached to the cantilever beam of the AFM), the contribution of the cell membrane is negligible.

Download Full-text