A combined experimental atomic force microscopy-based nanoindentation and computational modeling approach to unravel the key contributors to the time-dependent mechanical behavior of single cells

2016 ◽  
Vol 16 (1) ◽  
pp. 297-311 ◽  
Author(s):  
Cristina Florea ◽  
Petri Tanska ◽  
Mika E. Mononen ◽  
Chengjuan Qu ◽  
Mikko J. Lammi ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Computational Modeling ◽  
Mechanical Behavior ◽  
Single Cells ◽  
Time Dependent ◽  
Force Microscopy ◽  
Modeling Approach ◽  
Atomic Force

Time-Dependent Phase Segregation of Dendrimer/n-Alkylthiol Mixed-Monolayers on Au(111):  An Atomic Force Microscopy Study

Langmuir ◽  
1999 ◽  
Vol 15 (22) ◽  
pp. 7632-7638 ◽  
Author(s):  
William M. Lackowski ◽  
Joseph K. Campbell ◽  
Grant Edwards ◽  
Victor Chechik ◽  
Richard M. Crooks
Keyword(s):  
Atomic Force Microscopy ◽  
Phase Segregation ◽  
Microscopy Study ◽  
Time Dependent ◽  
Atomic Force Microscopy Study ◽  
Mixed Monolayers ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Investigating cell mechanics with atomic force microscopy

2015 ◽  
Vol 12 (104) ◽  
pp. 20140970 ◽  
Author(s):  
Kristina Haase ◽  
Andrew E. Pelling
Keyword(s):  
Atomic Force Microscopy ◽  
Cell Mechanics ◽  
Normal Cell ◽  
Mechanical Characterization ◽  
Nonlinear Models ◽  
Single Cells ◽  
Mechanistic Models ◽  
Force Microscopy ◽  
Atomic Force ◽  
Inelastic Responses

Transmission of mechanical force is crucial for normal cell development and functioning. However, the process of mechanotransduction cannot be studied in isolation from cell mechanics. Thus, in order to understand how cells ‘feel’, we must first understand how they deform and recover from physical perturbations. Owing to its versatility, atomic force microscopy (AFM) has become a popular tool to study intrinsic cellular mechanical properties. Used to directly manipulate and examine whole and subcellular reactions, AFM allows for top-down and reconstitutive approaches to mechanical characterization. These studies show that the responses of cells and their components are complex, and largely depend on the magnitude and time scale of loading. In this review, we generally describe the mechanotransductive process through discussion of well-known mechanosensors. We then focus on discussion of recent examples where AFM is used to specifically probe the elastic and inelastic responses of single cells undergoing deformation. We present a brief overview of classical and current models often used to characterize observed cellular phenomena in response to force. Both simple mechanistic models and complex nonlinear models have been used to describe the observed cellular behaviours, however a unifying description of cell mechanics has not yet been resolved.

scholarly journals Modulation of the contractility of micropatterned myocardial cells with nanoscale forces using atomic force microscopy

2016 ◽  
Vol 3 ◽  
pp. 184954351667534 ◽  
Author(s):  
Neerajha Nagarajan ◽  
Varun Vyas ◽  
Bryan D Huey ◽  
Pinar Zorlutuna
Keyword(s):  
Atomic Force Microscopy ◽  
Single Cells ◽  
Neonatal Rat ◽  
Contraction Rate ◽  
Rat Cardiomyocytes ◽  
Force Microscopy ◽  
Glass Substrates ◽  
Atomic Force ◽  
Lower Magnitude ◽  
Cyclic Stimulation

The ability to modulate cardiomyocyte contractility is important for bioengineering applications ranging from heart disease treatments to biorobotics. In this study, we examined the changes in contraction frequency of neonatal rat cardiomyocytes upon single-cell-level nanoscale mechanical stimulation using atomic force microscopy. To measure the response of same density of cells, they were micropatterned into micropatches of fixed geometry. To examine the effect of the substrate stiffness on the behavior of cells, they were cultured on a stiffer and a softer surface, glass and poly (dimethylsiloxane), respectively. Upon periodic cyclic stimulation of 300 nN at 5 Hz, a significant reduction in the rate of synchronous contraction of the cell patches on poly(dimethylsiloxane) substrates was observed with respect to their spontaneous beat rate, while the cell patches on glass substrates maintained or increased their contraction rate after the stimulation. On the other hand, single cells mostly maintained their contraction rate and could only withstand a lower magnitude of forces compared to micropatterned cell patches. This study reveals that the contraction behavior of cardiomyocytes can be modulated mechanically through cyclic nanomechanical stimulation, and the degree and mode of this modulation depend on the cell connectivity and substrate mechanical properties.

scholarly journals Reconstruction of Three-Dimensional Conformations of Bacterial ClpB from High-Speed Atomic-Force-Microscopy Images

2021 ◽  
Vol 8 ◽  
Author(s):  
Bhaskar Dasgupta ◽  
Osamu Miyashita ◽  
Takayuki Uchihashi ◽  
Florence Tama
Keyword(s):  
Atomic Force Microscopy ◽  
Computational Modeling ◽  
High Speed ◽  
3D Structure ◽  
Three Dimensional ◽  
3D Models ◽  
Computational Method ◽  
Molecular Surface ◽  
Force Microscopy ◽  
Atomic Force

ClpB belongs to the cellular disaggretase machinery involved in rescuing misfolded or aggregated proteins during heat or other cellular shocks. The function of this protein relies on the interconversion between different conformations in its native condition. A recent high-speed-atomic-force-microscopy (HS-AFM) experiment on ClpB from Thermus thermophilus shows four predominant conformational classes, namely, open, closed, spiral, and half-spiral. Analyses of AFM images provide only partial structural information regarding the molecular surface, and thus computational modeling of three-dimensional (3D) structures of these conformations should help interpret dynamical events related to ClpB functions. In this study, we reconstruct 3D models of ClpB from HS-AFM images in different conformational classes. We have applied our recently developed computational method based on a low-resolution representation of 3D structure using a Gaussian mixture model, combined with a Monte-Carlo sampling algorithm to optimize the agreement with target AFM images. After conformational sampling, we obtained models that reflect conformational variety embedded within the AFM images. From these reconstructed 3D models, we described, in terms of relative domain arrangement, the different types of ClpB oligomeric conformations observed by HS-AFM experiments. In particular, we highlighted the slippage of the monomeric components around the seam. This study demonstrates that such details of information, necessary for annotating the different conformational states involved in the ClpB function, can be obtained by combining HS-AFM images, even with limited resolution, and computational modeling.

scholarly journals nanite: using machine learning to assess the quality of atomic force microscopy-enabled nano-indentation data

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Paul Müller ◽  
Shada Abuhattum ◽  
Stephanie Möllmert ◽  
Elke Ulbricht ◽  
Anna V. Taubenberger ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Data Analysis ◽  
Supervised Learning ◽  
Mean Squared Error ◽  
Single Cells ◽  
Contact Point ◽  
Base Line ◽  
Force Microscopy ◽  
Nano Indentation ◽  
Atomic Force

Abstract Background Atomic force microscopy (AFM) allows the mechanical characterization of single cells and live tissue by quantifying force-distance (FD) data in nano-indentation experiments. One of the main problems when dealing with biological tissue is the fact that the measured FD curves can be disturbed. These disturbances are caused, for instance, by passive cell movement, adhesive forces between the AFM probe and the cell, or insufficient attachment of the tissue to the supporting cover slide. In practice, the resulting artifacts are easily spotted by an experimenter who then manually sorts out curves before proceeding with data evaluation. However, this manual sorting step becomes increasingly cumbersome for studies that involve numerous measurements or for quantitative imaging based on FD maps. Results We introduce the Python package nanite, which automates all basic aspects of FD data analysis, including data import, tip-sample separation, base line correction, contact point retrieval, and model fitting. In addition, nanite enables the automation of the sorting step using supervised learning. This learning approach relates subjective ratings to predefined features extracted from FD curves. For ratings ranging from 0 to 10, our approach achieves a mean squared error below 1.0 rating points and a classification accuracy between good and poor curves that is above 87%. We showcase our approach by quantifying Young’s moduli of the zebrafish spinal cord at different classification thresholds and by introducing data quality as a new dimension for quantitative AFM image analysis. Conclusion The addition of quality-based sorting using supervised learning enables a fully automated and reproducible FD data analysis pipeline for biological samples in AFM.

Investigation of the effect of substrate morphology on MDCK cell mechanical behavior using atomic force microscopy

2019 ◽  
Vol 115 (6) ◽  
pp. 063701 ◽  
Author(s):  
Keyvan Mollaeian ◽  
Yi Liu ◽  
Siyu Bi ◽  
Juan Ren
Keyword(s):  
Atomic Force Microscopy ◽  
Mechanical Behavior ◽  
Mdck Cell ◽  
Force Microscopy ◽  
Atomic Force

Imidazolium-Based Ionic Liquids Affect Morphology and Rigidity of Living Cells: an Atomic Force Microscopy Study

2018 ◽  
Author(s):  
Massimiliano Galluzzi ◽  
Carsten Schulte ◽  
Paolo Milani ◽  
Alessandro Podestà
Keyword(s):  
Atomic Force Microscopy ◽  
Ionic Liquids ◽  
Cell Membrane ◽  
Molecular Mechanisms ◽  
Single Cells ◽  
Metastatic Cancer ◽  
Toxic Effects ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Impact

The study of the toxicity, biocompatibility, and environmental sustainability of room-temperature Ionic Liquids (ILs) is still in its infancy. Understanding the impact of ILs on living organisms, especially from the aquatic ecosystem, is urgent, since on one side large amounts of these substances are widely employed as solvents in industrial chemical processes, and on the other side evidences of toxic effects of ILs on microorganisms and single cells have been observed. To date, the toxicity of ILs have been investigated by means of macroscopic assays aimed at characterizing the effective concentrations (like the EC50) that cause the dead of a significant fraction of the population of microorganisms and cells. These studies allowed to identify the cell membrane as the first target of the IL interaction, whose effectiveness was correlated to the lipophilicity of the cation, i.e. to the length of the lateral alkyl chain. Our study aimed at characterizing the molecular mechanisms of the toxicity of ILs. To this purpose, we carried out a combined topographic and mechanical analysis by Atomic Force Microscopy of living breast metastatic cancer cells (MDA-MB-231) upon interaction with imidazolium-based ILs. We showed that ILs are able to induce modifications of the overall rigidity (effective Young modulus) and morphology of the cells. Our results demonstrate that ILs act on the physical properties of the cell membrane, and possibly induce cytoskeletal reorganization, already at concentrations below the EC50. These potentially toxic effects are stronger at higher IL concentrations, as well as with longer lateral chains in the cation.<br>

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