Tensile testing of individual glassy, rubbery and hydrogel electrospun polymer nanofibres to high strain using the atomic force microscope

Gestos, Adrian; Whitten, Philip G.; Spinks, Geoffrey M.; Wallace, Gordon G.

doi:10.1016/j.polymertesting.2013.02.010

Cited by 19 publications

(7 citation statements)

References 84 publications

(81 reference statements)

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“….6 nN on 800-nm fibers. These forces correspond to fiber deflections averaging 3.2% of their span length, falling within the suggested elastic limit for polystyrene nanofibers (40,41). The force-time plot from a dual probe perturbation typically shows a steady rise in force as the cell is stretched while maintaining adhesion integrity, which is followed by a sharp drop as the cell-fiber adhesion fails, representative of the abrupt breaking failure typically observed (Fig.…”

Section: I)supporting

confidence: 62%

“…Three different diameters (250, 400, and 800 nm) were used in this study to obtain a wide range of curvature and structural stiffness values (3-50 nN/mm) as measured by AFM ramp tests (27,39). The structural stiffness values permit optically measurable deflection (>2 mm) under cell-scale loads while remaining in the elastic limit (deflection % 5% of the span length; (40,41); see the Supporting Material).…”

Section: Nanonet Scaffold Design Enables Force Measurementmentioning

confidence: 99%

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Nanonet Force Microscopy for Measuring Cell Forces

Sheets

Wang

Zhao

et al. 2016

Biophysical Journal

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The influence of physical forces exerted by or felt by cells on cell shape, migration, and cytoskeleton arrangement is now widely acknowledged and hypothesized to occur due to modulation of cellular inside-out forces in response to changes in the external fibrous environment (outside-in). Our previous work using the non-electrospinning Spinneret-based Tunable Engineered Parameters' suspended fibers has revealed that cells are able to sense and respond to changes in fiber curvature and structural stiffness as evidenced by alterations to focal adhesion cluster lengths. Here, we present the development and application of a suspended nanonet platform for measuring C2C12 mouse myoblast forces attached to fibers of three diameters (250, 400, and 800 nm) representing a wide range of structural stiffness (3-50 nN/μm). The nanonet force microscopy platform measures cell adhesion forces in response to symmetric and asymmetric external perturbation in single and cyclic modes. We find that contractility-based, inside-out forces are evenly distributed at the edges of the cell, and that forces are dependent on fiber structural stiffness. Additionally, external perturbation in symmetric and asymmetric modes biases cell-fiber failure location without affecting the outside-in forces of cell-fiber adhesion. We then extend the platform to measure forces of (1) cell-cell junctions, (2) single cells undergoing cyclic perturbation in the presence of drugs, and (3) cancerous single-cells transitioning from a blebbing to a pseudopodial morphology.

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Section: I)supporting

confidence: 62%

Section: Nanonet Scaffold Design Enables Force Measurementmentioning

confidence: 99%

Nanonet Force Microscopy for Measuring Cell Forces

Sheets

Wang

Zhao

et al. 2016

Biophysical Journal

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“…An important variation in the traditional single fiber tensile test is the development of three point tensile test, where the cantilever apex tip stretches the fiber attached to TEM (Transmission Electron Microscopy) grids with an adhesive by dragging it laterally [70].…”

mentioning

confidence: 99%

Post Processing Strategies for the Enhancement of Mechanical Properties of ENMs (Electrospun Nanofibrous Membranes): A Review

2021

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Electrospinning is a versatile technique which results in the formation of a fine web of fibers. The mechanical properties of electrospun fibers depend on the choice of solution constituents, processing parameters, environmental conditions, and collector design. Once electrospun, the fibrous web has little mechanical integrity and needs post fabrication treatments for enhancing its mechanical properties. The treatment strategies include both the chemical and physical techniques. The effect of these post fabrication treatments on the properties of electrospun membranes can be assessed through either conducting tests on extracted single fiber specimens or macro scale testing on membrane specimens. The latter scenario is more common in the literature due to its simplicity and low cost. In this review, a detailed literature survey of post fabrication strength enhancement strategies adopted for electrospun membranes has been presented. For optimum effect, enhancement strategies have to be implemented without significant loss to fiber morphology even though fiber diameters, porosity, and pore tortuosity are usually affected. A discussion of these treatments on fiber crystallinity, diameters, and mechanical properties has also been produced. The choice of a particular post fabrication strength enhancement strategy is dictated by the application area intended for the membrane system and permissible changes to the initial fibrous morphology.

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“…This experimental procedure, depicted in Figure 2.21, looks at only a small vertical deflection from which only the elastic modulus can be determined. A slight modification to this configuration has been used to pull the fibre laterally, allowing for a larger deflection 162 .…”

Section: Fibre Mechanicsmentioning

confidence: 99%

“…Instead of vertical deflection, the lateral deflection of an AFM cantilever can be used as a force sensor for measuring the tensile properties of individual electrospun polymer nanofibres suspended across trenches 162 . The fibres were electrospun and glued onto a parallel bar TEM grid where the spaces between the bars act as trenches that are deep enough to allow the AFM cantilever to hook onto the fibre and pull it laterally as shown in Figure 2.22.…”

Section: Fibre Mechanicsmentioning

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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Tensile testing of individual glassy, rubbery and hydrogel electrospun polymer nanofibres to high strain using the atomic force microscope

Cited by 19 publications

References 84 publications

Nanonet Force Microscopy for Measuring Cell Forces

Nanonet Force Microscopy for Measuring Cell Forces

Post Processing Strategies for the Enhancement of Mechanical Properties of ENMs (Electrospun Nanofibrous Membranes): A Review

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

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