scholarly journals Analytical model of atomic-force-microscopy force curves in viscoelastic materials exhibiting power law relaxation

2017 ◽  
Vol 121 (3) ◽  
pp. 034901 ◽  
Author(s):  
J. S. de Sousa ◽  
J. A. C. Santos ◽  
E. B. Barros ◽  
L. M. R. Alencar ◽  
W. T. Cruz ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Analytical Model ◽  
Power Law ◽  
Viscoelastic Materials ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Curves

scholarly journals Surface Structure and Nanomechanical Properties of Shewanella putrefaciens Bacteria at Two pH values (4 and 10) Determined by Atomic Force Microscopy

2005 ◽  
Vol 187 (11) ◽  
pp. 3864-3868 ◽  
Author(s):  
Fabien Gaboriaud ◽  
Sidney Bailet ◽  
Etienne Dague ◽  
Frédéric Jorand
Keyword(s):  
Atomic Force Microscopy ◽  
A Priori ◽  
Linear Part ◽  
Shewanella Putrefaciens ◽  
Nonlinear Part ◽  
Force Microscopy ◽  
Nanomechanical Properties ◽  
Ph Values ◽  
Atomic Force ◽  
Force Curves

ABSTRACT The nanomechanical properties of gram-negative bacteria (Shewanella putrefaciens) were investigated in situ in aqueous solutions at two pH values, specifically, 4 and 10, by atomic force microscopy (AFM). For both pH values, the approach force curves exhibited subsequent nonlinear and linear regimens that were related to the progressive indentation of the AFM tip in the bacterial cell wall, including a priori polymeric fringe (nonlinear part), while the linear part was ascribed to compression of the plasma membrane. These results indicate the dynamic of surface ultrastructure in response to changes in pH, leading to variations in nanomechanical properties, such as the Young's modulus and the bacterial spring constant.

scholarly journals Atomic force microscopy of the morphology and mechanical behaviour of barnacle cyprid footprint proteins at the nanoscale

2009 ◽  
Vol 7 (43) ◽  
pp. 285-296 ◽  
Author(s):  
In Yee Phang ◽  
Nick Aldred ◽  
Xing Yi Ling ◽  
Jurriaan Huskens ◽  
Anthony S. Clare ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sea Water ◽  
Persistence Length ◽  
Force Microscopy ◽  
Bond Model ◽  
Atomic Force ◽  
Extension Force ◽  
Force Curves ◽  
High Elongation ◽  
Glass Surfaces

Barnacles are a major biofouler of man-made underwater structures. Prior to settlement, cypris larvae explore surfaces by reversible attachment effected by a ‘temporary adhesive’. During this exploratory behaviour, cyprids deposit proteinaceous ‘footprints’ of a putatively adhesive material. In this study, footprints deposited by Balanus amphitrite cyprids were probed by atomic force microscopy (AFM) in artificial sea water (ASW) on silane-modified glass surfaces. AFM images obtained in air yielded better resolution than in ASW and revealed the fibrillar nature of the secretion, suggesting that the deposits were composed of single proteinaceous nanofibrils, or bundles of fibrils. The force curves generated in pull-off force experiments in sea water consisted of regions of gradually increasing force, separated by sharp drops in extension force manifesting a characteristic saw-tooth appearance. Following the relaxation of fibrils stretched to high strains, force–distance curves in reverse stretching experiments could be described by the entropic elasticity model of a polymer chain. When subjected to relaxation exceeding 500 ms, extended footprint proteins refolded, and again showed saw-tooth unfolding peaks in subsequent force cycles. Observed rupture and hysteresis behaviour were explained by the ‘sacrificial bond’ model. Longer durations of relaxation (>5 s) allowed more sacrificial bond reformation and contributed to enhanced energy dissipation (higher toughness). The persistence length for the protein chains ( L P ) was obtained. At high elongation, following repeated stretching up to increasing upper strain limits, footprint proteins detached at total stretched length of 10 µm.

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.

scholarly journals A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

2015 ◽  
Vol 6 ◽  
pp. 2233-2241 ◽  
Author(s):  
Santiago D Solares
Keyword(s):  
Atomic Force Microscopy ◽  
Computational Cost ◽  
Viscoelastic Model ◽  
Software Tool ◽  
Tapping Mode ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Standard Linear Solid ◽  
Force Curves

This paper introduces a quasi-3-dimensional (Q3D) viscoelastic model and software tool for use in atomic force microscopy (AFM) simulations. The model is based on a 2-dimensional array of standard linear solid (SLS) model elements. The well-known 1-dimensional SLS model is a textbook example in viscoelastic theory but is relatively new in AFM simulation. It is the simplest model that offers a qualitatively correct description of the most fundamental viscoelastic behaviors, namely stress relaxation and creep. However, this simple model does not reflect the correct curvature in the repulsive portion of the force curve, so its application in the quantitative interpretation of AFM experiments is relatively limited. In the proposed Q3D model the use of an array of SLS elements leads to force curves that have the typical upward curvature in the repulsive region, while still offering a very low computational cost. Furthermore, the use of a multidimensional model allows for the study of AFM tips having non-ideal geometries, which can be extremely useful in practice. Examples of typical force curves are provided for single- and multifrequency tapping-mode imaging, for both of which the force curves exhibit the expected features. Finally, a software tool to simulate amplitude and phase spectroscopy curves is provided, which can be easily modified to implement other controls schemes in order to aid in the interpretation of AFM experiments.

On averaging force curves over heterogeneous surfaces in atomic force microscopy

2012 ◽  
Vol 121 ◽  
pp. 16-24 ◽  
Author(s):  
I. Sokolov ◽  
V. Kalaparthi ◽  
M. Kreshchuk ◽  
M.E. Dokukin
Keyword(s):  
Atomic Force Microscopy ◽  
Heterogeneous Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Curves

Mapping of Nanoscale Mechanical Properties of Polymers in Quasi-static and Oscillatory Atomic Force Microscopy Modes

MRS Advances ◽  
2016 ◽  
Vol 1 (40) ◽  
pp. 2763-2768 ◽  
Author(s):  
Sergei Magonov ◽  
Marko Surtchev ◽  
John Alexander ◽  
Ivan Malovichko ◽  
Sergey Belikov
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Polymer Materials ◽  
Work Of Adhesion ◽  
Force Microscopy ◽  
Atomic Force ◽  
Time Dependencies ◽  
Force Curves ◽  
20 Nm

ABSTRACTRecent advances in studies of local mechanical properties of polymers with different atomic force microscopy techniques (contact, Hybrid and amplitude modulation modes) are described in interplay between experiment and theory. Analysis of force curves and time dependencies of probe response to sample compliance, which were recorded on a number of polymer materials at various temperatures, leads to quantitative mapping of specific mechanical properties (elastic modulus, work of adhesion, etc). High spatial resolution of elastic modulus mapping (10-20 nm) is illustrated in measurements of lamellar structures of several polymers. Challenges of examination of viscoelastic properties are pointed out and a possible solution is presented.

Automated detection of protein unfolding events in atomic force microscopy force curves

2016 ◽  
Vol 79 (11) ◽  
pp. 1105-1111 ◽  
Author(s):  
Xavier García-Massó ◽  
Matthias C. Huber ◽  
Jacqueline. Friedmann ◽  
Luis M. Gonzalez ◽  
Stefan M. Schiller ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Protein Unfolding ◽  
Automated Detection ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Curves
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