Controlled tip wear on high roughness surfaces yields gradual broadening and rounding of cantilever tips

Vorselen, Daan; Kooreman, Ernst S.; Wuite, Gijs J. L.; Roos, Wouter H.

doi:10.1038/srep36972

Cited by 24 publications

(17 citation statements)

References 33 publications

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“…To test this hypothesis, we used an approach based on AFM tip wear on high roughness surfaces. 25 Such wear leads to increased tip size, while the tip maintains its spherical apex, identical tip material and cantilever properties (Figure 2b, insets and Figure S5). The tip radius ( R t ) was estimated using blind tip reconstruction.…”

Section: Resultsmentioning

confidence: 99%

“…To establish the role of tip size we applied a recently introduced method for broadening tip size without compromising the spherical apex of the tip. 25 Additionally, this method does not affect tip chemical properties or cantilever properties. The difference in mechanical response we observed here can be explained by the physical obstruction of lipid tether elongation by the tip leading to a stiffening of the response, which occurs earlier for broader tips.…”

Section: Discussionmentioning

confidence: 99%

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Competition between Bending and Internal Pressure Governs the Mechanics of Fluid Nanovesicles

et al. 2017

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Nanovesicles (∼100 nm) are ubiquitous in cell biology and an important vector for drug delivery. Mechanical properties of vesicles are known to influence cellular uptake, but the mechanism by which deformation dynamics affect internalization is poorly understood. This is partly due to the fact that experimental studies of the mechanics of such vesicles remain challenging, particularly at the nanometer scale where appropriate theoretical models have also been lacking. Here, we probe the mechanical properties of nanoscale liposomes using atomic force microscopy (AFM) indentation. The mechanical response of the nanovesicles shows initial linear behavior and subsequent flattening corresponding to inward tether formation. We derive a quantitative model, including the competing effects of internal pressure and membrane bending, that corresponds well to these experimental observations. Our results are consistent with a bending modulus of the lipid bilayer of ∼14kbT. Surprisingly, we find that vesicle stiffness is pressure dominated for adherent vesicles under physiological conditions. Our experimental method and quantitative theory represents a robust approach to study the mechanics of nanoscale vesicles, which are abundant in biology, as well as being of interest for the rational design of liposomal vectors for drug delivery.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Competition between Bending and Internal Pressure Governs the Mechanics of Fluid Nanovesicles

et al. 2017

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“…The membrane bending modulus can be derived by this model. This deformation behaviour, however, depends on the probe size 32,47 . Multilamellar vesicles have also been characterized, showing that the number of bilayers can be estimated and that the vesicle stiffness scales with lamellarity 157 .…”

Section: Case Studiesmentioning

confidence: 99%

Atomic force microscopy-based mechanobiology

et al. 2018

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Mechanobiology focuses on how physical forces and the mechanical properties of proteins, protein assemblies, cells and tissues contribute to signalling, development, cell division, differentiation and sorting, physiology and disease 1-4. On virtually any scale, ranging from organisms 2,4 to components such as organs 5,6 , tissues 3,7 , cells 8-10 , viruses 11,12 , complex extracellular or intracellular architecture (including vesicles, the extracellular matrix or actin network 13,14) or single proteins 15-17 , biological systems respond to mechanical forces and generate mechanical cues. In mechanobiology, living systems are described by cycles of mechanosensation, mechanotransduction and mechanoresponse 2,18. In addition to its state, the functional response of a living system depends on the nature of the mechanical signal, whether it is applied at the nanometre or micrometre scale, for a short or long time, with low or high magnitude, and on whether it is scalar or vectorial. Nanotechnological and microtechnological approaches have enabled tremendous progress in quantifying the mechanical properties of biological systems. The links between mechanical response, morphology and function, however, are conspicuously ill understood. The most widely used approaches to structurally map the mechanical properties and responses of biological systems, ranging from millimetre to sub-nanometre resolution and from micronewton to piconewton sensitivity, are based on atomic force microscopy (AFM) 19,20. In this Review, we survey the exciting developments in AFM-based approaches towards the morphological mapping of a wide variety of mechanical properties and the characterization of the functional response of biological systems under physiologically relevant conditions. We further discuss key challenges and caveats that have to be taken into account to overcome the limitations of AFM-based approaches to more fully describe the mechanical properties of living systems and highlight how complementary techniques can contribute to directly linking the functional responses of complex biological systems to mechanical cues. Characterizing biosystems by AFM The introduction of AFM in 1986 opened the door to imaging and manipulating matter at the atomic, molecular and cellular scales and was central to the nascent nanotechnological revolution 21,22. Of particular importance for the characterization of biological systems, atomic force microscopes can operate in aqueous environments and at physiological temperatures. In an atomic force microscope, a cantilever that is several micrometres long and has a molecularly sharp probe at the end is used to trace the sample topography, detecting

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“…This was done because of the high sensitivity of these measures to high-frequency noise. Sphericity was calculated as Ψ = (6π 1/3 V 2/3 S −1 )/2 1/3 , where the division by 2 1/3 was used when only the upper hemisphere was analyzed, as it is a correction that guarantees that Ψ cannot exceed 1 for non-closed shapes 49 . For surface curvature calculations, first principal curvatures (k 1 and k 2 ) of the triangulated mesh were determined as described previously 50,51 .…”

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confidence: 99%

Microparticle traction force microscopy reveals subcellular force exertion patterns in immune cell–target interactions

et al. 2020

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Force exertion is an integral part of cellular behavior. Traction force microscopy (TFM) has been instrumental for studying such forces, providing spatial force measurements at subcellular resolution. However, the applications of classical TFM are restricted by the typical planar geometry. Here, we develop a particle-based force sensing strategy for studying cellular interactions. We establish a straightforward batch approach for synthesizing uniform, deformable and tuneable hydrogel particles, which can also be easily derivatized. The 3D shape of such particles can be resolved with superresolution (<50 nm) accuracy using conventional confocal microscopy. We introduce a reference-free computational method allowing inference of traction forces with high sensitivity directly from the particle shape. We illustrate the potential of this approach by revealing subcellular force patterns throughout phagocytic engulfment and force dynamics in the cytotoxic T-cell immunological synapse. This strategy can readily be adapted for studying cellular forces in a wide range of applications.

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Controlled tip wear on high roughness surfaces yields gradual broadening and rounding of cantilever tips

Cited by 24 publications

References 33 publications

Competition between Bending and Internal Pressure Governs the Mechanics of Fluid Nanovesicles

Competition between Bending and Internal Pressure Governs the Mechanics of Fluid Nanovesicles

Atomic force microscopy-based mechanobiology

Microparticle traction force microscopy reveals subcellular force exertion patterns in immune cell–target interactions

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