A nano-cheese-cutter to directly measure interfacial adhesion of freestanding nano-fibers

Wang, Xin; Najem, Johnny F.; Wong, Shing Chung Josh; Wan, Kai‐Tak

doi:10.1063/1.3677947

Cited by 20 publications

(32 citation statements)

References 22 publications

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“…As the AFM cantilever is compliant, it is bending into the opposite direction, δ c , while the sample is indented by δ s . Thus, raw AFM force–displacement between ( F vs. y ) needs to be converted to the relation between applied force and cell deformation ( F vs. δ s ) by correcting cantilever deflection from the piezo displacement (Wang et al ., ,b, ). According to the spherical Hertzian contact mechanical model, the constitutive relation for a rigid spherical probe with radius of R AFM pressing vertically on an elastic half continuum with elastic modulus, E , and Poisson's ratio, ʋ = 0.50, is used to compute the cell elastic modulus, given by

E = \frac{3}{4} (\frac{1 - ν^{2}}{R_{AFM}^{1 / 2}}) \frac{\partial F}{\partial ({italicδ}_{s}^{3 / 2})} .

…”

Section: Methodsmentioning

confidence: 99%

Mammary epithelium‐specific inactivation of V‐ATPase reduces stiffness of extracellular matrix and enhances metastasis of breast cancer

et al. 2017

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Extracellular matrix (ECM) critically impacts tumor progression and is influenced by both cancer and host tissue cells. While our understanding of cancer cell ECM remodeling is widespread, the importance of host tissue ECM, which provides initial congenial environment for primary tumor formation, is partly understood. Here, we report a novel role of epithelial cell‐associated vacuolar ATPase ‘a2’ isoform (a2V) in regulating breast tissue ECM stiffness to control metastasis. Using a mammary gland‐specific a2V‐knockout model, we show that in the absence of a2V, breast tumors exhibit atypically soft tumor phenotype, less tumor rigidity, and necrotic tumor microenvironment. These tumors contain a decreased number of cancer cells at primary tumor site, but showed extensive metastases compared to control. Nanomechanical evaluation of normal breast tissues revealed a decrease in stiffness and collagen content in ECM of a2V‐deleted breast tissues. Mechanistically, inhibition of a2V expression caused dispersed Golgi morphology with relocation of glycosyltransferase enzymes to early endosomes in mammary epithelial cells. This resulted in defective glycosylation of ECM proteins and production of compromised ECM that further influenced tumor metastasis. Clinically, in patients with cancer, low a2V expression levels in normal breast tissue correlated with lymph node metastasis. Thus, using a new knockout mouse model, we have identified a2V expression in epithelial cells as a key requirement for proper ECM formation in breast tissue and its expression levels can significantly modulate breast tumor dissemination. Evaluation of a2V expression in normal breast tissues can help in identifying patients with high risk of developing metastases.

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E = \frac{3}{4} (\frac{1 - ν^{2}}{R_{AFM}^{1 / 2}}) \frac{\partial F}{\partial ({italicδ}_{s}^{3 / 2})} .

…”

Section: Methodsmentioning

confidence: 99%

Mammary epithelium‐specific inactivation of V‐ATPase reduces stiffness of extracellular matrix and enhances metastasis of breast cancer

et al. 2017

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“…While we do not consider nonlinear material response here, the use of the present model is nonetheless informative, as we seek to eliminate the bending regime, which generally corresponds to small strains where elasticity plays a role. The maximum bending strain occurs at the outer skin, i.e., y = h/2: One can calculate the bending strain at this location for a given position according tô bending [Xj -' (12) As one would expect, the bending strain is maximum at the clamp and under the point-load (and those two are equal because of symmetry).…”

Section: Design Of Experimentsmentioning

confidence: 99%

“…There are a host of previous experimental studies and theoretical frameworks that utilize some aspects of the results presented here [1, [5][6][7][8][9][10]12,13,[19][20][21], The current work is a more comprehensive treatment of the response of point-loaded beams in the following respects. First, it includes an analysis that accounts for all levels of residual strain, across the full range of loads and displacements for moderate rotations.…”

Section: Introductionmentioning

confidence: 98%

“…thin films is to measure the load-deflection relationship of a freestanding structure, such as a thin beam or wire (e.g., membranes [1-4], microbeams [5,6] and wires [7,8]). Such methods are increasingly popular because a wide range of loads and displacements can be accessed using existing off-the-shelf systems, such as atomic force microscopes (AFM) [7][8][9][10][11][12][13], nanoindentation systems, profi]ometers, and instrumented microindenters [1- 6,14,15]. Further, the preparation of specimens amenable to one-dimensional modeling (i.e., beams and wires) is increasingly straightforward with emerging micro-and nanofabrication techniques [16,17].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comprehensive Solutions for the Response of Freestanding Beams With Tensile Residual Stress Subject to Point-Loading

Gaskins

Barker

Begley

2013

Journal of Applied Mechanics

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This paper provides comprehensive solutions for the load-deflection response of an elastic beam with tensile residual stresses subjected to point-loading. A highly accurate explicit approximation is derived from the exact implicit solution for moderate rotations, which greatly facilitates property extraction and the design of devices for materials characterization, actuation, and sensing. The approximation has less than 6% error across the entire range of loads, displacements, geometry, and residual stress levels. An illustration of the application of the theory is provided for microfabricated nickel beams. The explicit form provides straightfon'ard estimates for the critical loads and deflection defining the limits where classical asymptotic limits (e.g., pretensioned membrane, plate, and nonlinear membrane) will be accurate. Regimes maps are presented that identify critical loads, displacements, and properties correspond to these behaviors. Finally, the explicit form also enables straightforward estimations of bending strains relative to stretching, which is useful in the design of materials experiments that can be approximated as uniform straining of the beams.

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“…This includes taping freestanding fibres to cardboard mounts 163,164 or gluing between two microspheres on an AFM cantilever 165 as shown in Figure 2.24. Two fibres are arranged orthogonal to each other at the midpoint in a cross-cylinder configuration and pressed into contact for a given time.…”

Section: Experimental Approaches For Fibre-fibre Measurementmentioning

confidence: 99%

Bio-tribology of plant cell walls: measuring the interactive forces between cell wall components

Dolan¹

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Plants have naturally evolved complex cell wall structures to give mechanical and friction properties that facilitate plant growth and development. A biomimetic approach is employed to gain insight into how plants are able to lubricate moving surfaces at multiple length scales. The outcomes of this study advance the fundamental scientific understanding of plant cell wall biology.New insights provided here may have significant implications for optimising the value of plant material as a food source, biofuel precursor, and as a model for functional biomaterial design, particularly for medical applications. A review of the plant cell wall structure, mechanics, and extension processes is used to identify the forces and tribological contacts that are relevant for plant growth. Plant cell walls are essentially hydrogel composites of cellulose fibres within a matrix of biopolymers (e.g. hemicelluloses, pectin) and water. Plant tissue is comprised of a cluster of plant cells where adjacent cell walls are mediated by a pectin rich middle lamella layer. Plant growth is initiated by expansins which are proteins that disrupt cellulose fibre contact points, leading to the extension of the cell wall matrix. As cells expand within the tissue structure, a sliding contact forms between adjacent walls that are extending at different rates. The two critical length scales that are considered here to influence plant growth are the contact between cellulose nano-fibres in the cell wall matrix, and the sliding interface between adjacent cell walls.A large component of this thesis is the development of techniques to mimic the two tribological contacts; that is, fibre-fibre and cell-cell interactions. The sliding interface between two surfaces is achieved using a rotational rheometer, which also allows in situ material characterisation of the surfaces with pre-compression, relaxation, and oscillatory shear mechanical testing steps. The interactive forces between nano-fibres are measured directly using an Atomic Force Microscope (AFM) tip to laterally pull fibres out of a network. Bacterial cellulose networks are used as a model system that is compatible with the developed techniques. Bacterial cellulose is a good model because of the structural similarity to plant cellulose, and its ability to grow as a self-assembled random fibre network with the shape and dimensions controlled by the vessel within which it is grown. The lubricating role of individual cell wall components at the two tribological contacts is examined; including arabinoxylan (AX), xyloglucan (XG), pectin, and expansins. This is achieved ii by growing composite bacterial cellulose networks with AX and XG, and by adding pectin or expansin solutions to the liquid medium surrounding the pre-formed cellulose networks during testing.The unique aspect of this mechanical study is that the experimental results are analysed using computation modelling. Appropriate models are used to simulate the behaviour of fibrous assemblies at multiple length scales, and under condition...

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A nano-cheese-cutter to directly measure interfacial adhesion of freestanding nano-fibers

Abstract: A comparative study of spin coated and floating film transfer method coated poly (3-hexylthiophene)/poly (3-hexylthiophene)-nanofibers based field effect transistors

Cited by 20 publications

References 22 publications

Mammary epithelium‐specific inactivation of V‐ATPase reduces stiffness of extracellular matrix and enhances metastasis of breast cancer

Mammary epithelium‐specific inactivation of V‐ATPase reduces stiffness of extracellular matrix and enhances metastasis of breast cancer

Comprehensive Solutions for the Response of Freestanding Beams With Tensile Residual Stress Subject to Point-Loading

Bio-tribology of plant cell walls: measuring the interactive forces between cell wall components

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