scholarly journals Probe Sensitivity to Cortical versus Intracellular Cytoskeletal Network Stiffness

2018 ◽  
Author(s):  
Amir Vahabakashi ◽  
Chan Young Park ◽  
Kristin Perkumas ◽  
Zhiguo Zhang ◽  
Emily K. Deurloo ◽  
...  
Keyword(s):  
Relative Sensitivity ◽  
Cell Types ◽  
Biomechanical Properties ◽  
Experimental Conditions ◽  
Element Analysis ◽  
Knock Out ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cytoskeletal Network ◽  
Traction Microscopy

ABSTRACTIn development, wound healing, and pathology, cell biomechanical properties are increasingly recognized as being of central importance. To measure these properties, experimental probes of various types have been developed, but how each probe reflects the properties of heterogeneous cell regions has remained obscure. To better understand differences attributable to the probe technology, as well as to define the relative sensitivity of each probe to different cellular structures, here we took a comprehensive approach. We studied two cell types --Schlemm’s canal (SC) endothelial cells and mouse embryonic fibroblasts (MEFs) – using four different probe technologies: 1) atomic force microscopy (AFM) with sharp-tip; 2) AFM with round-tip; 3) optical magnetic twisting cytometry (OMTC); and 4) traction microscopy (TM). Perturbation of SC cells with dexamethasone treatment, a-actinin overexpression, or Rho-A overexpression caused increases in traction reported by TM and stiffness reported by sharp-tip AFM, as compared to corresponding controls. By contrast, under these same experimental conditions, stiffness reported by round-tip AFM and by OMTC indicated little change. Knock out (KO) of vimentin in MEFs caused a diminution of traction reported by TM, as well as stiffness reported by sharp-tip and round-tip AFM. However, stiffness reported by OMTC in vimentin KO MEFs was greater than in wild-type. Finite element analysis demonstrated that this paradoxical OMTC result in vimentin KO MEFs could be attributed to reduced cell thickness. Our results also suggest that vimentin contributes not only to intracellular network stiffness but also cortex stiffness. Taken together, this evidence suggests that AFM sharp-tip and TM emphasize properties of the actin-rich shell of the cell whereas round-tip AFM and OMTC emphasize those of the non-cortical intracellular network.

scholarly journals Biomechanics of Neutrophil Tethers

Life ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 515
Author(s):  
Andrea Cugno ◽  
Alex Marki ◽  
Klaus Ley
Keyword(s):  
Cell Activation ◽  
Optical Trap ◽  
Biomechanical Properties ◽  
Force Microscopy ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Microfluidic Flow ◽  
Biomembrane Force Probe ◽  
Membrane Reservoir

Leukocytes, including neutrophils, which are propelled by blood flow, can roll on inflamed endothelium using transient bonds between selectins and their ligands, and integrins and their ligands. When such receptor–ligand bonds last long enough, the leukocyte microvilli become extended and eventually form thin, 20 m long tethers. Tether formation can be observed in blood vessels in vivo and in microfluidic flow chambers. Tethers can also be extracted using micropipette aspiration, biomembrane force probe, optical trap, or atomic force microscopy approaches. Here, we review the biomechanical properties of leukocyte tethers as gleaned from such measurements and discuss the advantages and disadvantages of each approach. We also review and discuss viscoelastic models that describe the dependence of tether formation on time, force, rate of loading, and cell activation. We close by emphasizing the need to combine experimental observations with quantitative models and computer simulations to understand how tether formation is affected by membrane tension, membrane reservoir, and interactions of the membrane with the cytoskeleton.

Sensor Egregium – An Atomic Force Microscope Sensor for Continuously Variable Resonance Amplification

2021 ◽  
pp. 1-23
Author(s):  
Rafiul Shihab ◽  
Tasmirul Jalil ◽  
Burak Gulsacan ◽  
Matteo Aureli ◽  
Ryan Tung
Keyword(s):  
Finite Element Analysis ◽  
Atomic Force Microscope ◽  
Natural Frequencies ◽  
Proof Of Concept ◽  
Element Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Curve Veering ◽  
Dynamic Phenomena

Abstract Numerous nanometrology techniques concerned with probing a wide range of frequency dependent properties would benefit from a cantilevered sensor with tunable natural frequencies. In this work, we propose a method to arbitrarily tune the stiffness and natural frequencies of a microplate sensor for atomic force microscope applications, thereby allowing resonance amplification at a broad range of frequencies. This method is predicated on the principle of curvature-based stiffening. A macroscale experiment is conducted to verify the feasibility of the method. Next, a microscale finite element analysis is conducted on a proof-of-concept device. We show that both the stiffness and various natural frequencies of the device can be highly controlled through applied transverse curvature. Dynamic phenomena encountered in the method, such as eigenvalue curve veering, are discussed and methods are presented to accommodate these phenomena. We believe that this study will facilitate the development of future curvature-based microscale sensors for atomic force microscopy applications.

scholarly journals The measurement of biomechanical properties of porcine articular cartilage using atomic force microscopy

2009 ◽  
Vol 72 (4/5) ◽  
pp. 251-259 ◽  
Author(s):  
Raphael Imer ◽  
Terunobu Akiyama ◽  
Nico F. de Rooij ◽  
Martin Stolz ◽  
Ueli Aebi ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Articular Cartilage ◽  
Biomechanical Properties ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Chemotherapy exposure increases leukemia cell stiffness

Blood ◽  
2006 ◽  
Vol 109 (8) ◽  
pp. 3505-3508 ◽  
Author(s):  
Wilbur A. Lam ◽  
Michael J. Rosenbluth ◽  
Daniel A. Fletcher
Keyword(s):  
Cell Death ◽  
Leukemia Cell ◽  
Vascular Complications ◽  
Cell Types ◽  
Cell Stiffness ◽  
Microfluidic Channels ◽  
Cell Deformability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Acute Myeloid Leukemia Cells

Abstract Deformability of blood cells is known to influence vascular flow and contribute to vascular complications. Medications for hematologic diseases have the potential to modulate these complications if they alter blood cell deformability. Here we report the effect of chemotherapy on leukemia cell mechanical properties. Acute lymphoblastic and acute myeloid leukemia cells were incubated with standard induction chemotherapy, and individual cell stiffness was tracked with atomic force microscopy. When exposed to dexamethasone or daunorubicin, leukemia cell stiffness increased by nearly 2 orders of magnitude, which decreased their passage through microfluidic channels. This stiffness increase occurred before caspase activation and peaked after completion of cell death, and the rate of stiffness increase depended on chemotherapy type. Stiffening with cell death occurred for all cell types investigated and may be due to dynamic changes in the actin cytoskeleton. These observations suggest that chemotherapy itself may increase the risk of vascular complications in acute leukemia.

scholarly journals Oscillatory Microrheology, Creep Compliance and Stress Relaxation of Biological Cells Reveal Strong Correlations as Probed by Atomic Force Microscopy

2021 ◽  
Vol 9 ◽  
Author(s):  
D.A.D. Flormann ◽  
C. Anton ◽  
M.O. Pohland ◽  
Y. Bautz ◽  
K. Kaub ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Stress Relaxation ◽  
Optical Tweezers ◽  
Power Law ◽  
Creep Compliance ◽  
Culture Dish ◽  
Experimental Conditions ◽  
Force Microscopy ◽  
Atomic Force

The mechanical properties of cells are important for many biological processes, including wound healing, cancers, and embryogenesis. Currently, our understanding of cell mechanical properties remains incomplete. Different techniques have been used to probe different aspects of the mechanical properties of cells, among them microplate rheology, optical tweezers, micropipette aspiration, and magnetic twisting cytometry. These techniques have given rise to different theoretical descriptions, reaching from simple Kelvin-Voigt or Maxwell models to fractional such as power law models, and their combinations. Atomic force microscopy (AFM) is a flexible technique that enables global and local probing of adherent cells. Here, using an AFM, we indented single retinal pigmented epithelium cells adhering to the bottom of a culture dish. The indentation was performed at two locations: above the nucleus, and towards the periphery of the cell. We applied creep compliance, stress relaxation, and oscillatory rheological tests to wild type and drug modified cells. Considering known fractional and semi-fractional descriptions, we found the extracted parameters to correlate. Moreover, the Young’s modulus as obtained from the initial indentation strongly correlated with all of the parameters from the applied power-law descriptions. Our study shows that the results from different rheological tests are directly comparable. This can be used in the future, for example, to reduce the number of measurements in planned experiments. Apparently, under these experimental conditions, the cells possess a limited number of degrees of freedom as their rheological properties change.

A Novel Plate-Like Sensor Utilizing Curvature-Based Stiffening for Nanometrology Applications

2020 ◽  
Author(s):  
Rafiul Shihab ◽  
Tasmirul Jalil ◽  
Burak Gulsacan ◽  
Matteo Aureli ◽  
Ryan C. Tung
Keyword(s):  
Finite Element Analysis ◽  
Atomic Force Microscopy ◽  
Natural Frequencies ◽  
Piezoelectric Actuators ◽  
Static Stiffness ◽  
Element Analysis ◽  
Force Microscopy ◽  
Transverse Curvature ◽  
Atomic Force

Abstract In this study, we propose a novel plate-like sensor which utilizes curvature-based stiffening effects for enhanced nanometrology. In the proposed concept, the stiffness and natural frequencies of the sensor can be arbitrarily adjusted by applying a transverse curvature via piezoelectric actuators, thereby enabling resonance amplification over a broad range of frequencies. The concept is validated using a macroscale experiment. Then, a microscale finite element analysis is used to study the effect of applied curvature on the microplate static stiffness and natural frequencies. We show that imposed transverse curvature is an effective way to tune the in-situ static stiffness and natural frequencies of the plate sensor system. These findings will form the basis of future curvature-based stiffening microscale studies for novel scenarios in atomic force microscopy.

scholarly journals Finite element analysis of V-shaped cantilevers for atomic force microscopy under normal and lateral force loads

2006 ◽  
Vol 38 (6) ◽  
pp. 1090-1095 ◽  
Author(s):  
Matthias Müller ◽  
Thomas Schimmel ◽  
Pascal Häußler ◽  
Heiko Fettig ◽  
Ottmar Müller ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Atomic Force Microscopy ◽  
Finite Element ◽  
Lateral Force ◽  
Element Analysis ◽  
Force Microscopy ◽  
Atomic Force
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