Subsurface Imaging of Functionalized and Polymer-Grafted Graphene Oxide

Dehnert, Martin; Spitzner, Eike-Christian; Beckert, Fabian; Friedrich, Christian; Magerle, R.

doi:10.1021/acs.macromol.6b01519

Cited by 16 publications

(9 citation statements)

References 80 publications

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“…The phase shift signal was used to generate subsurface images of polymeric materials. 318,319 The hydration of biopolymers under different conditions was followed by recording phase shift-distance curves. 320,321 Several viscoelastic processes on polymer blends and polymer nanocomposites have been studied by AFM phase contrast images.…”

Section: The Paradox Of Afm Phase-imagingmentioning

confidence: 99%

Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications

2020

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Section: The Paradox Of Afm Phase-imagingmentioning

confidence: 99%

Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications

2020

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“…The reconstructed MUSIC-mode AFM images are free from feedback loop artifacts and allow for quantitative and depth-resolved imaging of soft polymeric surfaces with unprecedented spatial resolution and detail. 22,44,45,[52][53][54] Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Unraveling capillary interaction and viscoelastic response in atomic force microscopy of hydrated collagen fibrils

Uhlig

Magerle

2017

Nanoscale

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The mechanical properties of collagen fibrils depend on the amount and the distribution of water molecules within the fibrils. Here, we use atomic force microscopy (AFM) to study the effect of hydration on the viscoelastic properties of reconstituted type I collagen fibrils in air with controlled relative humidity. With the same AFM tip, we investigate the same area of a collagen fibril with two different force spectroscopy methods: force-distance (FD) and amplitude-phase-distance (APD) measurements. This allows us to separate the contributions of the fibril's viscoelastic response and the capillary force to the tip-sample interaction. A water bridge forms between the tip apex and the surface, causing an attractive capillary force, which is the main contribution to the energy dissipated from the tip to the specimen in dynamic AFM. The force hysteresis in the FD measurements and the tip indentation of only 2 nm in the APD measurements show that the hydrated collagen fibril is a viscoelastic solid. The mechanical properties of the gap regions and the overlap regions in the fibril's D-band pattern differ only in the top 2 nm but not in the fibril's bulk. We attribute this to the reduced number of intermolecular crosslinks in the reconstituted collagen fibril. The presented methodology allows the mechanical surface properties of hydrated collagenous tissues and biomaterials to be studied with unprecedented detail on the nanometer scale.

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“…In previous work on reassembled type I collagen fibrils, we showed that AFM imaging in air with controlled humidity restores the fibril’s water content and allows high-resolution imaging. , We also learned how the attractive capillary tip–sample interaction can be discriminated from a fibril’s viscoelastic response . In studies of polymeric nanostructures, we constructed 3D depth profiles of the local tip–sample interaction from maps of APD data. − Roduit et al showed how depth-resolved stiffness profiles can be constructed from FD data. Here, we employ these AFM-based 3D depth-profiling techniques to study native (unfixed) tendons.…”

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Nanomechanical 3D Depth Profiling of Collagen Fibrils in Native Tendon

et al. 2020

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Connective tissue displays a large compositional and structural complexity that involves multiple length scales. In particular, on the molecular and the nanometer level, the elementary processes that determine the biomechanics of collagen fibrils in connective tissues are still poorly understood. Here, we use atomic force microscopy (AFM) to determine the three-dimensional (3D) depth profiles of the local nanomechanical properties of collagen fibrils and their embedding interfibrillar matrix in native (unfixed), hydrated Achilles tendon of sheep and chickens. AFM imaging in air with controlled humidity preserves the tissue’s water content, allowing the assembly of collagen fibrils to be imaged in high resolution beneath an approximately 5–10 nm thick layer of the fluid components of the interfibrillar matrix. We collect pointwise force–distance (FD) data and amplitude–phase–distance (APD) data, from which we construct 3D depth profiles of the local tip–sample interaction forces. The 3D images reveal the nanomechanical morphology of unfixed, hydrated collagen fibrils in native tendon with a 0.1 nm depth resolution and a 10 nm lateral resolution. We observe a diversity in the nanomechanical properties among individual collagen fibrils in their adhesive and in their repulsive, viscoelastic mechanical response as well as among the contact points between adjacent collagen fibrils. This sheds new light on the role of interfibrillar bonds and the mechanical properties of the interfibrillar matrix in the biomechanics of tendon.

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Subsurface Imaging of Functionalized and Polymer-Grafted Graphene Oxide

Cited by 16 publications

References 80 publications

Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications

Nanomechanical mapping of soft materials with the atomic force microscope: methods, theory and applications

Unraveling capillary interaction and viscoelastic response in atomic force microscopy of hydrated collagen fibrils

Nanomechanical 3D Depth Profiling of Collagen Fibrils in Native Tendon

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